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The Athlete's Clock
How Biology and Time Affect Sport Performance
Edited by Thomas W. Rowland
232 Pages
The Athlete’s Clock: How Biology and Time Affect Sport Performance offers an engaging, interdisciplinary consideration of some of the most compelling questions in sport and exercise science. This unique text takes a broad look at the physiological clock, offering students, researchers, coaches, and athletes a unique approach to understanding how various aspects of time affect sport performance.
The Athlete’s Clock explores the ways in which time and its relationship to athletic effort can optimize sport performance. Readers can investigate challenging questions such as these:
•If physiological responses to training vary rhythmically throughout the day, what is the optimal time of day for training?
•If a coach thinks that a high stroke count leads to a better time in a particular swim event, should the athlete go with it? Or is it better to stick to a more intuitively normal cadence?
•Do endurance athletes consciously control their pacing, or are they under the control of unconscious processes within the central nervous system?
•In what ways do aging and rhythmic biological variations over time control athletic performance?
•Can athletes use cognitive strategies to subdue or overcome limits imposed by biological factors out of their control?
Readers will find information on the mechanisms by which time influences physiological function—such as running speeds and muscle activation—and how those mechanisms can be used in extending the limits of motor activity. Chapter introductions cue readers to the ideas addressed in the chapter, and sidebars throughout present amusing or unusual examples of sport and timing within various contexts. In addition, take-home messages at the end of each chapter summarize important findings and research that readers may apply in their own lives.
Addressing one of the most intriguing questions in sports, a conversational interview with athlete development expert, anthropologist, and sport scientist Bob Malina covers the timely topic of sport identification and talent development. The interview is an engaging discussion of how and when talent identification should take place and how talent development for young, promising athletes might proceed. The text also considers how time throughout one’s life span alters motor function, particularly in the later years.
The Athlete’s Clock: How Biology and Time Affect Sport Performance blends physiological, psychological, and philosophical perspectives to provide an intelligent and whimsical look at the effects of timing in sport and exercise. This text seeks to provoke thought and further research that look at the relationship between biology, time, and performance as well as an understanding of and appreciation for the intricacies of human potential.
Chapter 1. Who’s in Charge Here? Setting the Race Pace
Chapter 2. Marching to the Same Drummer: Cadence in Endurance Events
Chapter 3. Dragsters, Tiger Beetles, and Usain Bolt: Time and Speed
Chapter 4. Circadian Rhythms and Sport Performance
Chapter 5. It’s All in the Timing: Keeping Your Eye on the Ball
Chapter 6. Peaks and Valleys: The Development of Athletic Skill—A Conversation
With Bob Malina
Chapter 7. Over The Hill: Aging and Sport Performance
Thomas W. Rowland, MD, is director of pediatric cardiology at the Baystate Medical Center in Springfield, Massachusetts, where he established an exercise testing laboratory. The author of Children’s Exercise Physiology, Second Edition, and editor of the journal Pediatric Exercise Science, he has extensive research experience in exercise physiology of children.
Rowland has served as president of the North American Society for Pediatric Exercise Medicine (NASPEM) and was on the board of trustees of the American College of Sports Medicine (ACSM). He is past president of the New England chapter of the ACSM and received the ACSM Honor Award in 1993.
Since receiving BS and MD degrees from the University of Michigan in 1965 and 1969, Rowland has been an assistant and associate professor of pediatrics at the University of Massachusetts Medical School in Worcester (1977 to 1990) and an assistant and associate clinical professor of pediatrics at Tufts University School of Medicine in Boston (1975 to the present). He is professor of pediatrics at Tufts University School of Medicine and a past adjunct professor of exercise science at the University of Massachusetts.
Rowland is a competitive tennis player and distance runner. He and his wife, Margot, reside in Longmeadow, Massachusetts. In his free time he enjoys playing tennis, running, and acting.
“This is an excellent broad introduction to the idea of time and sport. It offers scientific research to support many of the questions athletes and coaches ask themselves when determining strategy in a sport event.”
—Doody’s Book Review (5-star review)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)
Do external cues affect the way athletes think about pacing?
The concept of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding velocity based on previous experience and sensory input.
Cognitive Pacing Strategy
Experienced distance athletes know how they feel during a race. From having competed in similar distances in the past, they know just how intense such perceptions of effort should be in order to predict exhaustion at the finish. Breathing too hard and experiencing leg-muscle stress in the first kilometer of a 10K race cause runners to conclude that they will not make it at this pace. They consciously slow their velocity. Conversely, being too comfortable in the early phases of a race signals them to speed up.
This traditional model of pacing is rooted in the idea that athletes make cognitive, purposeful decisions regarding running velocity based on previous experience and sensory input. But which cues do they use to make these velocity adjustments?
Exercise scientists measure how athletes feel as their rating of perceived exertion (RPE). Here, athletes report subjective sensations of exercise stress, usually on a numerical scale ranging from 6 to 20. (This is called a Borg scale, with the top number indicating the very highest level of fatigue.) This, then, is an attempt to put an objective measure (a number) to a subjective feeling (“How hard does it feel?”). Using this tool, the goal of researchers has been to identify the physiological (heart and lung function, body temperature), metabolic (blood acidity, lactate levels), and neuromuscular (muscle stress) factors that are most important in signaling the athletes' level of subjective stress during a distance competition. By monitoring all this input, then, competitors figure out how to adjust race velocity to provide their best effort for a particular competition distance.
However, which particular input cues are the most critical in this strategizing are not entirely clear. A whole variety is possible, but despite a good deal of research, physiologists remain pretty much in the dark as to exactly how the athlete senses level of effort. Heart rate, oxygen uptake, and rate and depth of breathing have all been linked to RPE, as have blood-lactate level, availability of blood sugar, body temperature, and blood or muscle pH (acidity). Since all of these factors are in fact altered with increased work intensity, however, it is difficult to determine which, if any, actually cause changes in RPE. (Author's note: An informal survey of running acquaintances would seem to confirm personal experience that the agonizing discomfort of labored breathing is the most prominent signal of stress in a 5K or 10K road race. Does it help to recognize that this gasping indicates that excessive carbon dioxide is building up in your blood during the buffering of lactic acid, which is now flooding out of your muscle cells? Nope. Not at all.)
You might think, too, that external cues, such as where you are in relation to other competitors, could be important. If you, the state cross country champion, are at the back of the pack, your pace is too slow. Split times, which are provided specifically to help competitors regulate velocity, should be expected to be particularly useful in regulating effort in a distance event. But, perhaps surprisingly, this conclusion has not always been supported by research findings.
For instance, Yumna Albertus and her colleagues at the University of Cape Town shamelessly deceived trained cyclists during 20K time trials to see if providing false split times would change their pacing strategy. On the first time trial, the split times were correct, but on the second trial, the first split was actually given at .775 kilometers. This was followed by an increase of 25 meters with each subsequent kilometer until the end, when the split was given at 1.25 kilometers. On a third trial, the fraudulent times were reversed. So, did all this trickery affect the cyclists' pacing strategy? Surprisingly, not at all. There were no differences in finish times among the three trials. RPE values were the same, too. In finding that the pattern of power output was similar during the three trials, the researchers could conclude that the pacing strategy didn't change, either. Their conclusion? Pacing strategy is regulated by intrinsic clues (how an athlete feels), rather than by distance feedback.
Another investigation by Hugh Morton from New Zealand in which subjects were deceived produced different results. In this case, soccer players were asked to cycle to exhaustion (at a set resistance and cadence) on three occasions while facing a large digital clock. They didn't know that the clock was rigged to show the normal time on one occasion, to run 10% slower another time, and to run 10% faster the third. The results: When the clock ran slow, aerobic endurance time averaged 18% higher, compared to the session with normal time. There was no effect on aerobic endurance time, however, with the fast clock.
It was uncertain how to explain all this. The author himself was puzzled, concluding that “the psychological mechanisms behind the findings in this study are unclear.” But there does seem to be evidence here that external cues—in this case, the knowledge of time—are important in defining exercise tolerance. One conclusion is sure, though. If you are asked to be a subject in a pacing study, check the administrator's honesty first.
(The parallel to these deception studies in the real world of road racing obviously occurs when split times are erroneous because of inaccurately placed mile markers. This becomes evident when you find you've just passed the first-mile split, having shaved a full three minutes off the world record for this distance.)
This, then, is the customary way that coaches and distance athletes think about pacing. The competitors are in charge. They step up to the starting line, anticipating an average race speed based on previous events. Then, based on an awareness of how they feel, sensory input from the body's physiological state, plus extrinsic cues (split times), they modify their rate of muscular work (pace) during the race. These factors contribute to their optimal overall finishing time for that particular day and set of race conditions.
Can synchronizing stride rhythm and breathing help performance?
In athletes, stride rhythm is often coupled with breathing while running, walking, cycling, or rowing. This is called entrainment of ventilation and locomotion.
Entrainment of Locomotion and Breathing
One particularly intriguing observation that may have bearing on the organization of intrinsic clocks is that stride rhythm is often coupled with breathing during locomotion. That is, for a certain number of strides, there is a breath. This is called entrainment of ventilation and locomotion, and it has been observed in cats, dogs, horses, jackrabbits, gerbils, rhinoceroses, wallabies, turtles, guinea fowl, alligators—pretty much the whole ark.
Given this evidence for the evolutionary persistence of entrainment in the animal kingdom, it is no surprise that the phenomenon is also observed in humans who are running, walking, cycling, or rowing. In human studies, the reported frequency of the link between breathing and striding has varied widely. (In fact, some have found no evidence of entrainment at all.) Perhaps insightful, though, are the observations of Dennis Bramble and David Carrier at the University of Utah that the frequency of entrainment depends on the performance level of the runner. Experienced runners commonly coupled stride and breathing patterns very tightly. The most common ratio was a 2:1 ratio of strides and breaths, but at slow running speeds, this was frequently 4:1. However, in less talented runners, no synchronization of breathing and striding was observed at all. (So, here's another laboratory exercise to try. Check yourself for breathing-striding entrainment during your next run and see which category you're in.)
The explanations for the link between breathing and striding during locomotion have generally involved mechanical issues. Gait, for instance, may physically constrain breathing, thus requiring the two to be synchronized. However, such mechanisms would seem to be less likely linked during the upright bipedal locomotion of human beings. Alternatively, a combination of effects of a single internal clock that links the two different forms of rhythmic activity is an intriguing possibility.
Does entrainment help performance? It depends, it seems, on which expert you talk to. Jack Daniels, who was introduced earlier in this chapter, thinks so. Given his extensive experience as an athlete (U.S. national titlist in the modern pentathlon), coach (University of Texas, SUNY at Cortland), and exercise physiologist (University of Wisconsin), he's somebody who should know. He notes that the best runners use a 2-2 rhythm, taking two steps (one with each foot) during inhalation and two steps during exhalation. If you're striding at Daniel's proffered rate (90 steps with each foot per minute), you'll then be taking around 45 breaths per minute. He believes this provides the most efficient ventilation of the lungs.
So, according to his renowned book Daniels' Running Formula, a 2-2 rhythm is preferred for the majority of a distance race. However, near the finish, you will probably want to breath faster, around 60 breaths per minute. Then you can switch to a 1-2 rhythm (take one step while breathing in and two while breathing out), or 2-1. Slower rhythms, such as 3-3 and 4-4, might be okay for easy training runs. Daniels says to avoid a 1-1 pattern because the shallow breaths decrease actual lung air exchange.
Jerry Dempsey is to respiratory exercise physiology as Jack Daniels is to distance running coaching. And Dr. Dempsey disagrees. “My argument, purely theoretical, is as follows. We have shown that the oxygen cost of breathing at maximal exercise in highly trained athletes can comprise as much as 15% of the total oxygen demand. This means a fair bit of blood flow is being required by respiratory muscles that is potentially stolen from locomotor muscles. So we need our breathing to be as mechanically efficient as possible. To me, the mechanisms in the brain stem are best designed to receive all of the input from the lung, chest wall, cerebellum, and hypothalamus in order to sculpt the optimal depth and rate of each breath to minimize the work of respiratory muscles. Higher centers, including the cortex, willing our breathing pattern to coordinate with limb movement would not provide the same level of optimization. So, in essence, I believe the brain stem of the runner is better equipped than the cerebral cortex of a coach to determine breathing pattern.”
Distance runners Paul Norton and Jack Mahurin, whom you met in the previous chapter, line up with Professor Dempsey on this one. They both told me that anything that departs from just doing what comes naturally with your breathing is counterproductive. They think that concentrating on creating a certain pattern of breathing and striding wastes mental effort.
So, it comes right back to chapter 1's argument of the subconscious central governor versus our own conscious dictates, doesn't it? Should we let Mother Nature, with centuries of evolutionary practice, have her way? Or can we consciously adopt certain running (or in this case, running and breathing) strategies that will improve performance? I guess if people like Professors Dempsey and Daniels can't agree, we can safely call the answer inconclusive. But there may be a takeaway suggestion, too: Runners can try out active entrainment to see if it works.
Experts discuss which factors may dictate future athletic success in youth
Studies indicate a disproportionate number of professional athletes are born in the first quarter of the year, and grow up in cities with populations less than 500,000 but greater than 10,000.
Malina: Numerous studies have documented this effect.Rosters of participants in youth sports, particularly hockey, are biased toward those with birth dates in the first portion of the year, as compared to the last. The usual explanation is that those who are chronologically older are also more likely to be more biologically mature—stronger, heavier, and taller—offering a competitive advantage. No surprises here. Yet it is intriguing that this same bias for early birth date is seen in highly successful young-adult athletes after puberty as well. Studies of competitors in professional baseball, ice hockey, soccer, and basketball have all indicated a skewing of birthdates toward the quarter of each sport year. Somehow, the early maturers, who are more talented early on, seem to have continued to dominate in their sport. How to explain this? I believe that the size and performance advantages of early maturing boys within their respective age groups attract the attention of coaches and others interested in the search for talent.
Rowland: Before leaving this point, it should be added that in addition to birth date, location of birth also seems to be important. If you want to be a star athlete, grow up in Austin, not New York City or Miller's Corners. Well, that's a bit of hyperbole, but the point is that studies indicate a disproportionate number of professional athletes grow up in cities with populations less than 500,000 but greater than 10,000. Psychosocial environment seems to have some importance in the pathway to sport success. For example, Jean Côté and coworkers reported that about half of the U.S. population lives in cities with more than 500,000 inhabitants, but these cities account for only 13% of National Hockey League players, 29% of professional basketball players, 15% of participants in major league baseball, and 13% of the players in the Professional Golf Association.
Malina: Agreed. Did they provide any explanation for these findings?
Rowland: Well, you can pick your favorite explanation among the many offered: better physical environment of the smaller cities with more unstructured play activities permitting experience in different sports, more local support for sport teams, less competitive milieu, greater chance for early success, and so on.
Malina: So, where did you grow up, Tom?
Rowland: Alma, Michigan.
Malina: That explains everything.
Rowland: Could be. So, remember, we have been talking here about the steady, normal improvements in motor performance that occur as children grow. No training, just normal development, governed by growth-promoting hormones and affected by genetic endowment and level of sexual development.
Malina: We should add a third component, behavioral development, to this normal progression, too. This is a cultural concept. In their social milieu, children develop cognitively, socially, emotionally, and morally—they are learning to behave within the constructs of our society. This also applies to motor development and sports, specifically societal expectations and rewards associated with proficiency or lack of proficiency. The demands of sports may influence, or even sometimes conflict, with this normal behavioral development.
All three of these trends—physical growth, biological maturation, and behavioral development—are in a state of constant change and interaction during childhood and adolescence, and the rates of change and interactions vary greatly from one child to the next. So when thinking about the effects of sport training on children, we must appreciate that adult-organized programs are superimposed on a constantly changing base.
Rowland: Let's turn now to the effect of athletic training on the natural progression of events. To what extent can athletic training accelerate the normal improvements in physical performance of children and adolescents as they grow (that is, beyond the stimuli provided by Mother Nature)? And, as a corollary, can a child's ultimate development into a performing athlete be enhanced by early sport training?
Just to be clear, by training, we mean a program of systematic instruction and practice of certain frequency, intensity, and duration. That improvement in sport skill should be achieved through training is based on the precept that regular exercise stresses body tissues, which, in response, compensate by improving function. That function is then translated into greater performance outcomes. Also, in sports involving complex neuromuscular skill, such as tennis, there is the concept that repeated practice grooves neuromuscular connections, providing a kind of muscle memory.
Malina: It should be readily apparent that when thinking about the applicability of these principles to youth, a number of considerations are important. For instance, are the children at a proper stage of readiness or preparedness to respond to such stimuli in terms of their personal stages of growth and development? Are there critical periods when children are optimally sensitive to improvements associated with instruction and practice (in the case of sport skills) and physical training (regarding biological dimensions and functions)? How do differences in coaching strategies and instructional techniques at different ages make a difference? Our understanding of these issues is very limited.
Rowland: Let's begin by considering some examples of physiological fitness. Like muscle strength. It wasn't that long ago that people felt that it was impossible, and maybe even dangerous, for children to try to improve their muscle strength with resistance training, like lifting weights, before puberty. It was thought that you had to have circulating testosterone to do this. But now we know this is false. A good number of studies have documented that children, both boys and girls, gain strength in properly designed programs, just as adults do. So, we should expect that weight training would help children improve performance in sporting events where strength is an issue, most directly in, say, wrestling or powerlifting, but also in football, swimming, and even baseball. The studies haven't been done yet to really prove this, but it makes sense.
Aerobic endurance performance, like distance running, is associated with V.O2max, the highest amount of oxygen utilized by the body in an exercise test on a cycle or treadmill. With a period of aerobic endurance training, children typically show a rise in V.O2max, on the average about 5 to 6%. Since that number is less than what is observed in adults (15-20%), some have suggested that this implies that prepubescent children might be less trainable than adults in aerobic endurance sports. But it is not clear if the dampened response of V.O2max to training in children can be translated into a similarly limited increase in aerobic endurance performance itself. That's because performance on, say, a 5K road race is dependent not only on V.O2max but also on factors like economy of running energy.
Physical activity and other factors may delay the aging process
We take a closer look at studies into the effects daily activity and caloric restriction have on animals, and what the results might mean for humans.
Physical Activity and Longevity
It is now well recognized that those who are physically active, on the average, survive longer than those living sedentary lives. The research data clearly indicate that this is specifically an expression of the favorable effect of habitual energy expenditure on secondary aging. Regular exercise reduces health risk factors (dyslipidemia, hypertension, obesity, reduced bone density). In addition, it may have direct protective effects against the atherosclerotic vascular process. Athletes who maintain high levels of sport activity through their adult years can expect to benefit from limited secondary aging.
Whether high levels of physical activity can extend the natural, or primary, aging process is not known, but at present, no evidence supports that idea. The question, of course, would be extraordinarily difficult to address in the experimental setting for human beings. The best we can do is look at animals, who don't live as long and can be coerced to participate as long-term research subjects more easily. Too, in animals, we can expect to more distinctly examine the effects of exercise on the primary aging process.
In a particularly pertinent study (at least for rodents), John Holloszy and Bill Kohrt described the influence of regular running on the longevity of healthy rats who experienced no associated decline in food intake or growth retardation. Beginning at 4 months of age, 62 rats were housed in cages with running wheels. They started out exercising spontaneously an average of 9,173 meters per day. Running distances gradually decreased, falling to 965 meters daily at 34 months of age. Compared with nonexercising control rats, the running rats demonstrated an average life span that was 9% greater (1009 ± 132 days versus 924 days ± 155 days). There was, however, no significant difference between the two groups in maximal duration of life. The age of death of the two oldest rats was 1239 ± 14 days and 1199 ± 44 days in the runners and nonrunners, respectively.
What Factors Delay Primary Aging?
At the present time, only two documented means exist of extending the duration of primary aging—calorie-restricted diets and genetic manipulation. Both of these lines of evidence have been established in animals. As of this moment, their potential application to humans is a tantalizing idea that has not been well explored.
Caloric Restriction
Although the science of aging is generally clouded in mystery, one piece of experimental data has been repeatedly established: In animals, a low-calorie diet that is sufficient in specific nutrients (does not lead to malnutrition) will extend life span. This was first documented in 1917 in rats, and the effect has since been replicated in a wide variety of animals, ranging from fleas to monkeys. The usual experimental technique is to reduce caloric input to about 60% of ad libitum, which can be expected to prolong animal life by 25 to 40%. Just how this works is uncertain. Some have suggested that caloric restriction protects mitochondrial function, preserves activity of the electron transport chain, or blocks the deleterious actions of reactive oxygen species. Certain biochemical actions associated with caloric restriction in animals have been observed in humans as well, leading to speculation that H. sapiens might similarly benefit from extension of the life span.
Genetic Manipulation
If you happen to be a nematode worm—or are closely related to one—there is hope for you. More than 20 years ago, investigators reported that a single gene mutation in C. elegans significantly lengthened the worm's life span, as much as sixfold in some cases. Since that time, antiaging gene mutants have been described in a large number of organisms. The most advanced in terms of evolution is the mouse (with increases that are much more conservative, at 50 to 60%). How these genetic changes act to extend life remains problematic, but it is interesting that most of these gene loci share some connection with alterations in insulin signaling pathways.
It's almost needless to say that the explosive growth in techniques to manipulate gene loci in humans has fueled speculation that someday such fountain-of-youth interventions might extend human life, maybe (gasp!) indefinitely. (This, I believe, should be differentiated from the ideas of Friedrich Nietzsche, who claimed that we will forever relive our lives, just as the time before. The alert reader is, of course, conscious of the similarity of this concept of eternal return to Bill Murray's plight in the film Groundhog Day.)
What About Secondary Aging?
We all know that the increase in average life span over the past century is linked to reduced risks of infectious diseases and avoidance of health risk factors such as high-calorie diets, smoking, physical inactivity, and high blood pressure. Dr. Alexander Leaf wanted to look at this more closely. So, he left the safe confines of Massachusetts General Hospital one day and set out to visit remote populations reputed for their longevity in places like Hunza, a kingdom in the Hindu Kush mountains on the China-Afghanistan border; Georgia; and Vilcabamba, in the Andes mountains of Ecuador. (It turned out that the actual longevity of these people was in some doubt. In the latter village, for instance, the oldest citizen was supposedly 134 years old, but turned out at his death to be actually 93.)
Dr. Leaf describes his observations as “a monotonous litany of similar lifestyles.”1 He witnessed the following in all three locations:
- Poor, agrarian culture in which daily hard labor was the norm
- Vigorous daily physical activity beginning in childhood and persisting throughout life
- A vegetarian diet
- Strong support for the elderly
“No one retired or was put on the shelf to feel redundant and useless,” he observed. “Chores changed, but the elderly continued to do tasks that, although less vigorous, continued a useful role for them in the community and supported their self-esteem. Old age was greeted with respect rather than derision, and the elders were valued for their wisdom.”1
Food for thought!
Athletes and time
Athletes do their best to realize their genetic gifts and hard work in just a few clicks of the clock called competition. This phenomenon is seen through moments in time that serve to define the essence of sports itself.
Athletes, it hardly deserves stating, are no strangers to the importance of time. Sometimes, in fact, time is the very point of the sport. How much time elapses while you run 100 meters as fast as you can? In other sports, time regulates the duration of the competition. How many times can a group of five unusually tall players throw a ball through a round hoop in 40 minutes? Indeed, without a clock, most competitive sports would become quite meaningless. Yet, in other events, such as tennis or baseball, the timing of muscular action largely defines athletic skill.
Athletes are also keenly interested in their repeated performances over time. They become fixated on batting averages, fighting records, or field goal percentages. When repeated performances are unexpectedly poor, we talk about athletes being in a slump. When Michael Jordan sinks six three-pointers in a row in the NBA finals against Portland, he's on a hot streak. What explains these runs? Since the athletes have typically experienced no physical changes at the time, we say they are more (or less) mentally focused. We hear them described as trying too hard or, when on a roll, just letting it flow. Getting hot is something all athletes strive for (and would be willing, no doubt, to give a lot to know the secret of why it was happening).
It comes as a bit of surprise, then, that people who know a lot about the statistics of randomness are quick to pooh-pooh such explanations. Being hot or in a slump, they say, is just a matter of chance.
Thomas Gilovich from Cornell University teamed up with Stanford colleagues Robert Vallone and Amos Tversky to analyze the success of streak shooting of the Philadelphia 76ers professional basketball team during seasons from 1980 to 1982. Their findings? “Variations in shooting percentages across games do not deviate from their overall shooting percentages enough to produce significantly more hot (or cold) nights than expected by chance alone.”5
What they're saying is that if you flip a coin many, many times, you will eventually witness 10 heads in a row. Not often, but by chance, it will occur. And if you shoot a ball at a basket a large number of times, at some point, you will sink 10 in a row. Neither of you is more mentally focused. You're both in a groove, but only by statistical chance.5 (What bothers me about this analysis is that it seems that the people who have hot streaks always have names like DiMaggio and Jordan!)
Sometimes, too, athletes take great efforts to slow down time. Witness the interminable bouncing of the ball or tugging at the pants of my favorite pro tennis players (who will remain unnamed here) before they finally serve. Or the Yankees and the Red Sox, berated by umpires for taking their sweet time. Not to mention golfers on the PGA tour who dawdle on the back nine. The most obvious, though, are the basketball teams in the era before the shot clock who tried to protect their lead by stalling out the final minutes of play (see chapter 3).
Athletes, too, are very conscious of how time is best proportioned as they construct their training schedules. This periodization, or pattern of training, appears to influence gains in performance and permits peaking for big events. Athletes need to decide just how many weeks they should use high- and low-intensity training, how many days a week to devote to speed work, how many days of rest they should take, and how many days they should taper before a big competition.
All that training gets funneled down into those small particles of time we call competition. That's what it's all about. Athletes have taken their genetic gifts, done everything in their power to enhance them, and now—in just a few clicks of the clock—they must realize them.
This phenomenon is seen through moments in time that, often in dramatic fashion, serve to define the essence of sports itself. Carlton Fisk willing his drive to left field into fair territory during the sixth game of the 1975 World Series. John Landy glancing over his left shoulder as Roger Bannister passed by him on the outside in the final lap to win the mile of the century in Vancouver. Michael Jordan in full flight above the rim. Here, time is stilled—at least in memories and photographs—and moments are imbued with powerful meaning for the world of competitive sports.
Some have attributed spiritual qualities to such moments. In his 1999 book The Tao of the Jump Shot (Seastone Publishers), John Mahoney writes, “Although the jump shot is a dynamic movement of energy, there is one unique point, a nearly measureless instant, during which the athlete remains frozen in space. The point of release, born in a moment of stillness. . .”
Sometimes, rarely, remarkably, athletes seem to transcend the tyranny of time altogether. Like Roger Bannister on the final straightaway: “There was no pain, only a great unity of movement and aim.” In the throes of supreme physical effort, they've been transported somewhere else, someplace where even the clock doesn't matter. Victor Price, in his short story “The Other Kingdom,” wrote about this:
As they entered the straight they moved into a purely physical kingdom. Nothing mattered now but to keep going. . . . It was a wave of feral aggression, a lust for power and at the same time a sacred terror, as though he were pursued by some fierce and inescapable beast. Life existed now only as far as the finishing tape. The element of time expanded and contracted simultaneously; a seriousness on the threshold of physical agony, where the actions of this one man were determining the fate of all men, and none of the rules of life applied anymore. There was no good, no evil, no success, no failure. There was only the man eternally running. . . .6
(Alas, for most of us mere mortals, crossing the finishing line of a race is more likely to be accompanied by waves of nausea, hunger for air, cramps, and the longing for a warm shower.)