Cutting-Edge Cycling

Because overtraining affects the physical responses to training and adaptation, the body must also contend with a wide array of psychosocial stressors, from sports-related (team dynamics, coaches) and environmental (frequent travel, altitude) challenges to personal (relationship, work, financial) issues. Given the multitude of potential contributing factors beyond the quantification of training load, isolating the direct cause of overtraining can be difficult. The primary determinant is likely different for each cyclist. For example, a masters cyclist who juggles training time with a demanding job and a young family may overtrain from an inability to manage these multiple responsibilities. Alternately, a keen junior cyclist just starting in the sport may overtrain from trying to ride too much too soon or may develop overuse injuries from riding overlarge gears. Therefore, the social context of the cyclist must be carefully considered in managing overtraining. In addition, underlying medical issues may predispose (e.g., history of depression) or directly contribute (e.g., injury) to the onset of OTS.

Stages of Overtraining

The principle of overload is fundamental to the process of improving fitness (McNicol et al. 2009). A period of stress followed by recovery results in a “supercompensation” in which the body adapts to the imposed stress and becomes stronger, thus improving performance. The human body is highly adaptable to the stresses imposed on it as long as the stress is not excessive.

The European College of Sport Science, in its 2006 position stand (Meeusen et al. 2006), presented overtraining as a continuum from the desired “normal” and functional overload and functional overreaching (FOR), through to nonfunctional overreaching (NFOR), and ultimately to overtraining syndrome (OTS) and burnout. Although this representation is possibly an oversimplification—debate continues about whether the process of overtraining is a continuum or a series of distinct and independent phases—having standardized definitions as a basis of discussion is helpful.

• Training. A process of overload that is used to disturb the body's normal state of fitness, which results in acute fatigue (one to two days at most), adaptation by the body, and ultimately an improvement in performance. This level of training is what we do most of the time, such as a few hard interval sessions followed by a day or two of easier rides over the course of a week, or two to three weeks of progressive overload followed by a recovery week of reduced training to permit the body to adapt to the stress.
• Overtraining. Within this paradigm, overtraining is used to describe a period in which greater than normal training stress is imposed. An example may be suddenly spending two weeks doing more and harder intervals than you have been used to doing or spending a week at an intense climbing camp in the mountains, where you put in long hours and do lots of hard climbing. As explained in the three definitions that follow, overtraining can be a normal and positive process of overload and supercompensation (see functional overreaching), or it can become a negative stimulus that is more than the cyclist can handle (see nonfunctional overreaching and overtraining syndrome).
• Functional overreaching (FOR). A process in which overtraining, possibly followed by a temporary drop-off in performance lasting days to at most several weeks, results in the body adapting by becoming stronger and thus being able to produce performances that exceed the previous baseline. A critical component of FOR is a period of adequate recovery following the period of overtraining. An example may be a cyclist who spends a week at a climbing camp in the mountains, recovers at home with an easy week, and then settles back into a more normal training program during which he sees his overall riding level improve.
• Nonfunctional overreaching (NFOR). An extreme level of overtraining, often associated with inadequate recovery, in which the drop-off in performance after a period of overload is prolonged and performance stagnates or remains at baseline or lower for weeks or even months. Besides causing physiological changes, this state is often accompanied by psychological disturbances such as irritability, increased fatigue, and decreased vigor. Hormonal disturbances also are more likely within this phase. For example, NFOR might occur if the cyclist returned from a week at the climbing camp and then, without taking a recovery period, continued to push his body by doing a few additional weeks of hard training, thinking that by doing so he could take advantage of his newfound fitness and motivation to reap even greater benefits. With sufficient rest, cyclists in NFOR typically recover over a period of several months.
• Overtraining syndrome (OTS). An extreme level of overtraining, in which performance becomes impaired for many months to years. A host of psychological and physiological impairments can be present, and cyclists who reach this level often burn out completely and quit the sport. In general, rarely does physical stress alone bring about a state of OTS. Rather, the use of the term syndrome is intentional in recognition of the numerous factors that may contribute to its onset. For example, to achieve a state of OTS, the cyclist from the NFOR example described in the previous paragraph would likely have had one or more prior instances of NFOR in addition to a period of increased stress in his home, work, or team life or a physical issue such as an overuse injury or weakened immune system. Think of OTS as the perfect storm of overtraining that you never want to come near!

Although power monitors make direct quantification of training load possible, no hard and fast equation can state that a certain amount of work defines normal training, FOR, NFOR, or OTS. First, all cyclists differ in their ability to respond to a particular workload. Two cyclists riding an identical workout will respond differently based on their number of years in the sport, their particular phase of periodized training, and even their training for the previous day or week. Just as it is pointless to expect your body composition, weight, and resting heart rate to match someone else's, it is equally senseless to expect your potential for overtraining to be similar to another's. Therefore, an individual approach must be applied to training and addressing the possibility of OTS. Even when looking at a single cyclist, predicting the effect of a particular workload can be difficult because the nature of a periodized training plan generally means a wide fluctuation in workload throughout the year, making it hard to establish a baseline for workload or performance.

Heart Rate Monitors

With improved fitness, the defining change in your body is that your cardiac output, or the volume of blood pumped by your heart each minute, increases. Cardiac output is simply heart rate multiplied by stroke volume; the latter is the volume of blood pumped with each heart beat. In an untrained individual, the maximal cardiac output can reach approximately 25 liters per minute, but an elite aerobic athlete may have a value of 35 liters or higher. Obviously, as more blood is pumped, more oxygen is delivered to the muscles, increasing your aerobic energy production. Physiologically, what are some of the major adaptations in your cardiovascular system to enable this?

• Your maximal heart rate will not change with fitness. This value is largely determined by genetics and age.
• Overall blood volume will increase slightly, and some correlation is found between higher aerobic fitness and higher blood volume (Sawka et al. 1992). This result occurs mostly because of increased plasma volume rather than more red blood cells, such that hematocrit (the fraction of solid to liquid in blood) usually decreases with fitness.
• The heart, like your leg muscles, becomes stronger and able to pump blood with greater force. This increase in contractility helps to increase the stroke volume, or the amount of blood pumped with each heart beat.
• Stroke volume also increases by improvements in your body's ability to return blood from the body to the heart, resulting in greater filling of the heart each time.
• The capillary network in your muscles increases in density, permitting greater blood flow to the muscles themselves.

As can be seen from the preceding description, the cardiovascular system is a complex interplay of many things going on inside the body. Overall, the body adjusts the heart rate to achieve a cardiac output that will deliver adequate blood, oxygen, and nutrients to the muscles during exercise. Heart rate is also affected by the nervous system, as can be seen at the start line of a bicycle race when your heart rate is at 150 beats per minute before the starting gun even goes off! Or you could be tired and pushing yourself harder than ever, yet your heart rate reaches only 160 beats per minute as compared with your normal 175 beats per minute at threshold. In both cases, your nervous system is sending signals to your heart that override your body's physiological demands for cardiac output.

Therefore, although heart rate is an indication of effort, it is an indirect one at best. Similar to a tachometer on a car that tells you how fast the pistons are pumping rather than how many horsepower the engine is producing, heart rate does not tell you the speed or power that you are generating on the bike, but only how fast the heart is pumping. Hunter likes to say that “heart rate tells me the ‘intensity of an athlete's intention,' and that can help me to better understand the athlete in workouts and races.” Also, heart rate can be influenced by many factors related and not related to exercise, such as sleep, caffeine intake, and hydration status. That being said, monitoring your heart rate is beneficial, and you can track fitness changes over time by comparing heart rate with the data channels.

Standing Versus Seated Pedaling

The first and most obvious weight-bearing exercise is running. A lot of energy is required not only to propel yourself forward but also to keep yourself upright and stable. Added to that is the impact force from landing on your feet with each stride. The combination of the two makes for a much higher heart rate, a greater metabolic rate, and more overall stress when running compared with cycling. Cycling is mostly a non-weight-bearing activity, and the bicycle is a highly efficient machine because it removes the impact forces and cradles your body in a position that greatly minimizes the need to support your body weight. But at times you have to stand when riding, and then you have to support a good deal of your body weight (figure 8.8). Whether it's on the flats, in the hills, or in a sprint, you are no longer supporting your weight on the saddle, and you have to rely on your muscles more to keep yourself upright.

Of course, standing typically requires more energy and makes you less economical, but it also leverages more of your body weight over the pedals and recruits additional muscles, thus making higher power output possible. For this reason, we're generally taught to keep the standing to a minimum and to stand only when we need extra power, such as when initiating an acceleration (e.g., sprint, breakaway) or when we need extra power while climbing. Wind resistance is also higher while standing because of the larger surface area exposed.

Millet et al. (2002) tested fit elite and pro cyclists riding for 6 minutes at 75 percent of V?O2max in a velodrome and while seated or standing on a 5.3 percent gradient hill. The cyclists also performed 30-second all-out sprints in the lab and while seated and standing on a gradual hill. Thanks to the improvements in technology, the researchers could take this study out into real terrain and use the subjects' own SRM-equipped bikes with portable gas analyzers, increasing the applicability of the study. As expected, heart rate was about eight beats per minute higher when standing compared with seated uphill. Ventilation was also higher, although no differences were seen in oxygen consumption. Cadence was similar at just under 60 revolutions per minute in both conditions. Most important, no differences were found in either gross efficiency (about 22.5 percent) or economy (4.7 kilojoules of power per liter of oxygen). In the 30-second tests, maximum and mean power were much higher in the standing position compared with the seated position (mean power of about 820 and 650 watts, respectively), despite similar cadences and blood lactate values.

Overall, the ability to produce higher power when sprinting and standing is obvious and intuitive, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, especially the finding that no differences occur in efficiency or economy whether standing or seated. This result means that, although standing creates more stress on the aerobic and cardiovascular system, it does not necessarily cause a decrease in efficiency itself. So standing is not going to cost more energy to perform when you factor in the greater power that you are generating. One obvious caveat is that extended standing while climbing must be practiced to optimize economy. Another caveat is that all the subjects in the study were young, lean, and light, averaging 67 kilograms. For bigger riders with more weight to support, the efficiency and economy equations might be tilted in favor of sitting.

Because overtraining affects the physical responses to training and adaptation, the body must also contend with a wide array of psychosocial stressors, from sports-related (team dynamics, coaches) and environmental (frequent travel, altitude) challenges to personal (relationship, work, financial) issues. Given the multitude of potential contributing factors beyond the quantification of training load, isolating the direct cause of overtraining can be difficult. The primary determinant is likely different for each cyclist. For example, a masters cyclist who juggles training time with a demanding job and a young family may overtrain from an inability to manage these multiple responsibilities. Alternately, a keen junior cyclist just starting in the sport may overtrain from trying to ride too much too soon or may develop overuse injuries from riding overlarge gears. Therefore, the social context of the cyclist must be carefully considered in managing overtraining. In addition, underlying medical issues may predispose (e.g., history of depression) or directly contribute (e.g., injury) to the onset of OTS.

Stages of Overtraining

The principle of overload is fundamental to the process of improving fitness (McNicol et al. 2009). A period of stress followed by recovery results in a “supercompensation” in which the body adapts to the imposed stress and becomes stronger, thus improving performance. The human body is highly adaptable to the stresses imposed on it as long as the stress is not excessive.

The European College of Sport Science, in its 2006 position stand (Meeusen et al. 2006), presented overtraining as a continuum from the desired “normal” and functional overload and functional overreaching (FOR), through to nonfunctional overreaching (NFOR), and ultimately to overtraining syndrome (OTS) and burnout. Although this representation is possibly an oversimplification—debate continues about whether the process of overtraining is a continuum or a series of distinct and independent phases—having standardized definitions as a basis of discussion is helpful.

• Training. A process of overload that is used to disturb the body's normal state of fitness, which results in acute fatigue (one to two days at most), adaptation by the body, and ultimately an improvement in performance. This level of training is what we do most of the time, such as a few hard interval sessions followed by a day or two of easier rides over the course of a week, or two to three weeks of progressive overload followed by a recovery week of reduced training to permit the body to adapt to the stress.
• Overtraining. Within this paradigm, overtraining is used to describe a period in which greater than normal training stress is imposed. An example may be suddenly spending two weeks doing more and harder intervals than you have been used to doing or spending a week at an intense climbing camp in the mountains, where you put in long hours and do lots of hard climbing. As explained in the three definitions that follow, overtraining can be a normal and positive process of overload and supercompensation (see functional overreaching), or it can become a negative stimulus that is more than the cyclist can handle (see nonfunctional overreaching and overtraining syndrome).
• Functional overreaching (FOR). A process in which overtraining, possibly followed by a temporary drop-off in performance lasting days to at most several weeks, results in the body adapting by becoming stronger and thus being able to produce performances that exceed the previous baseline. A critical component of FOR is a period of adequate recovery following the period of overtraining. An example may be a cyclist who spends a week at a climbing camp in the mountains, recovers at home with an easy week, and then settles back into a more normal training program during which he sees his overall riding level improve.
• Nonfunctional overreaching (NFOR). An extreme level of overtraining, often associated with inadequate recovery, in which the drop-off in performance after a period of overload is prolonged and performance stagnates or remains at baseline or lower for weeks or even months. Besides causing physiological changes, this state is often accompanied by psychological disturbances such as irritability, increased fatigue, and decreased vigor. Hormonal disturbances also are more likely within this phase. For example, NFOR might occur if the cyclist returned from a week at the climbing camp and then, without taking a recovery period, continued to push his body by doing a few additional weeks of hard training, thinking that by doing so he could take advantage of his newfound fitness and motivation to reap even greater benefits. With sufficient rest, cyclists in NFOR typically recover over a period of several months.
• Overtraining syndrome (OTS). An extreme level of overtraining, in which performance becomes impaired for many months to years. A host of psychological and physiological impairments can be present, and cyclists who reach this level often burn out completely and quit the sport. In general, rarely does physical stress alone bring about a state of OTS. Rather, the use of the term syndrome is intentional in recognition of the numerous factors that may contribute to its onset. For example, to achieve a state of OTS, the cyclist from the NFOR example described in the previous paragraph would likely have had one or more prior instances of NFOR in addition to a period of increased stress in his home, work, or team life or a physical issue such as an overuse injury or weakened immune system. Think of OTS as the perfect storm of overtraining that you never want to come near!

Although power monitors make direct quantification of training load possible, no hard and fast equation can state that a certain amount of work defines normal training, FOR, NFOR, or OTS. First, all cyclists differ in their ability to respond to a particular workload. Two cyclists riding an identical workout will respond differently based on their number of years in the sport, their particular phase of periodized training, and even their training for the previous day or week. Just as it is pointless to expect your body composition, weight, and resting heart rate to match someone else's, it is equally senseless to expect your potential for overtraining to be similar to another's. Therefore, an individual approach must be applied to training and addressing the possibility of OTS. Even when looking at a single cyclist, predicting the effect of a particular workload can be difficult because the nature of a periodized training plan generally means a wide fluctuation in workload throughout the year, making it hard to establish a baseline for workload or performance.

Heart Rate Monitors

With improved fitness, the defining change in your body is that your cardiac output, or the volume of blood pumped by your heart each minute, increases. Cardiac output is simply heart rate multiplied by stroke volume; the latter is the volume of blood pumped with each heart beat. In an untrained individual, the maximal cardiac output can reach approximately 25 liters per minute, but an elite aerobic athlete may have a value of 35 liters or higher. Obviously, as more blood is pumped, more oxygen is delivered to the muscles, increasing your aerobic energy production. Physiologically, what are some of the major adaptations in your cardiovascular system to enable this?

• Your maximal heart rate will not change with fitness. This value is largely determined by genetics and age.
• Overall blood volume will increase slightly, and some correlation is found between higher aerobic fitness and higher blood volume (Sawka et al. 1992). This result occurs mostly because of increased plasma volume rather than more red blood cells, such that hematocrit (the fraction of solid to liquid in blood) usually decreases with fitness.
• The heart, like your leg muscles, becomes stronger and able to pump blood with greater force. This increase in contractility helps to increase the stroke volume, or the amount of blood pumped with each heart beat.
• Stroke volume also increases by improvements in your body's ability to return blood from the body to the heart, resulting in greater filling of the heart each time.
• The capillary network in your muscles increases in density, permitting greater blood flow to the muscles themselves.

As can be seen from the preceding description, the cardiovascular system is a complex interplay of many things going on inside the body. Overall, the body adjusts the heart rate to achieve a cardiac output that will deliver adequate blood, oxygen, and nutrients to the muscles during exercise. Heart rate is also affected by the nervous system, as can be seen at the start line of a bicycle race when your heart rate is at 150 beats per minute before the starting gun even goes off! Or you could be tired and pushing yourself harder than ever, yet your heart rate reaches only 160 beats per minute as compared with your normal 175 beats per minute at threshold. In both cases, your nervous system is sending signals to your heart that override your body's physiological demands for cardiac output.

Therefore, although heart rate is an indication of effort, it is an indirect one at best. Similar to a tachometer on a car that tells you how fast the pistons are pumping rather than how many horsepower the engine is producing, heart rate does not tell you the speed or power that you are generating on the bike, but only how fast the heart is pumping. Hunter likes to say that “heart rate tells me the ‘intensity of an athlete's intention,' and that can help me to better understand the athlete in workouts and races.” Also, heart rate can be influenced by many factors related and not related to exercise, such as sleep, caffeine intake, and hydration status. That being said, monitoring your heart rate is beneficial, and you can track fitness changes over time by comparing heart rate with the data channels.

Standing Versus Seated Pedaling

The first and most obvious weight-bearing exercise is running. A lot of energy is required not only to propel yourself forward but also to keep yourself upright and stable. Added to that is the impact force from landing on your feet with each stride. The combination of the two makes for a much higher heart rate, a greater metabolic rate, and more overall stress when running compared with cycling. Cycling is mostly a non-weight-bearing activity, and the bicycle is a highly efficient machine because it removes the impact forces and cradles your body in a position that greatly minimizes the need to support your body weight. But at times you have to stand when riding, and then you have to support a good deal of your body weight (figure 8.8). Whether it's on the flats, in the hills, or in a sprint, you are no longer supporting your weight on the saddle, and you have to rely on your muscles more to keep yourself upright.

Of course, standing typically requires more energy and makes you less economical, but it also leverages more of your body weight over the pedals and recruits additional muscles, thus making higher power output possible. For this reason, we're generally taught to keep the standing to a minimum and to stand only when we need extra power, such as when initiating an acceleration (e.g., sprint, breakaway) or when we need extra power while climbing. Wind resistance is also higher while standing because of the larger surface area exposed.

Millet et al. (2002) tested fit elite and pro cyclists riding for 6 minutes at 75 percent of V?O2max in a velodrome and while seated or standing on a 5.3 percent gradient hill. The cyclists also performed 30-second all-out sprints in the lab and while seated and standing on a gradual hill. Thanks to the improvements in technology, the researchers could take this study out into real terrain and use the subjects' own SRM-equipped bikes with portable gas analyzers, increasing the applicability of the study. As expected, heart rate was about eight beats per minute higher when standing compared with seated uphill. Ventilation was also higher, although no differences were seen in oxygen consumption. Cadence was similar at just under 60 revolutions per minute in both conditions. Most important, no differences were found in either gross efficiency (about 22.5 percent) or economy (4.7 kilojoules of power per liter of oxygen). In the 30-second tests, maximum and mean power were much higher in the standing position compared with the seated position (mean power of about 820 and 650 watts, respectively), despite similar cadences and blood lactate values.

Overall, the ability to produce higher power when sprinting and standing is obvious and intuitive, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, especially the finding that no differences occur in efficiency or economy whether standing or seated. This result means that, although standing creates more stress on the aerobic and cardiovascular system, it does not necessarily cause a decrease in efficiency itself. So standing is not going to cost more energy to perform when you factor in the greater power that you are generating. One obvious caveat is that extended standing while climbing must be practiced to optimize economy. Another caveat is that all the subjects in the study were young, lean, and light, averaging 67 kilograms. For bigger riders with more weight to support, the efficiency and economy equations might be tilted in favor of sitting.

Because overtraining affects the physical responses to training and adaptation, the body must also contend with a wide array of psychosocial stressors, from sports-related (team dynamics, coaches) and environmental (frequent travel, altitude) challenges to personal (relationship, work, financial) issues. Given the multitude of potential contributing factors beyond the quantification of training load, isolating the direct cause of overtraining can be difficult. The primary determinant is likely different for each cyclist. For example, a masters cyclist who juggles training time with a demanding job and a young family may overtrain from an inability to manage these multiple responsibilities. Alternately, a keen junior cyclist just starting in the sport may overtrain from trying to ride too much too soon or may develop overuse injuries from riding overlarge gears. Therefore, the social context of the cyclist must be carefully considered in managing overtraining. In addition, underlying medical issues may predispose (e.g., history of depression) or directly contribute (e.g., injury) to the onset of OTS.

Stages of Overtraining

The principle of overload is fundamental to the process of improving fitness (McNicol et al. 2009). A period of stress followed by recovery results in a “supercompensation” in which the body adapts to the imposed stress and becomes stronger, thus improving performance. The human body is highly adaptable to the stresses imposed on it as long as the stress is not excessive.

The European College of Sport Science, in its 2006 position stand (Meeusen et al. 2006), presented overtraining as a continuum from the desired “normal” and functional overload and functional overreaching (FOR), through to nonfunctional overreaching (NFOR), and ultimately to overtraining syndrome (OTS) and burnout. Although this representation is possibly an oversimplification—debate continues about whether the process of overtraining is a continuum or a series of distinct and independent phases—having standardized definitions as a basis of discussion is helpful.

• Training. A process of overload that is used to disturb the body's normal state of fitness, which results in acute fatigue (one to two days at most), adaptation by the body, and ultimately an improvement in performance. This level of training is what we do most of the time, such as a few hard interval sessions followed by a day or two of easier rides over the course of a week, or two to three weeks of progressive overload followed by a recovery week of reduced training to permit the body to adapt to the stress.
• Overtraining. Within this paradigm, overtraining is used to describe a period in which greater than normal training stress is imposed. An example may be suddenly spending two weeks doing more and harder intervals than you have been used to doing or spending a week at an intense climbing camp in the mountains, where you put in long hours and do lots of hard climbing. As explained in the three definitions that follow, overtraining can be a normal and positive process of overload and supercompensation (see functional overreaching), or it can become a negative stimulus that is more than the cyclist can handle (see nonfunctional overreaching and overtraining syndrome).
• Functional overreaching (FOR). A process in which overtraining, possibly followed by a temporary drop-off in performance lasting days to at most several weeks, results in the body adapting by becoming stronger and thus being able to produce performances that exceed the previous baseline. A critical component of FOR is a period of adequate recovery following the period of overtraining. An example may be a cyclist who spends a week at a climbing camp in the mountains, recovers at home with an easy week, and then settles back into a more normal training program during which he sees his overall riding level improve.
• Nonfunctional overreaching (NFOR). An extreme level of overtraining, often associated with inadequate recovery, in which the drop-off in performance after a period of overload is prolonged and performance stagnates or remains at baseline or lower for weeks or even months. Besides causing physiological changes, this state is often accompanied by psychological disturbances such as irritability, increased fatigue, and decreased vigor. Hormonal disturbances also are more likely within this phase. For example, NFOR might occur if the cyclist returned from a week at the climbing camp and then, without taking a recovery period, continued to push his body by doing a few additional weeks of hard training, thinking that by doing so he could take advantage of his newfound fitness and motivation to reap even greater benefits. With sufficient rest, cyclists in NFOR typically recover over a period of several months.
• Overtraining syndrome (OTS). An extreme level of overtraining, in which performance becomes impaired for many months to years. A host of psychological and physiological impairments can be present, and cyclists who reach this level often burn out completely and quit the sport. In general, rarely does physical stress alone bring about a state of OTS. Rather, the use of the term syndrome is intentional in recognition of the numerous factors that may contribute to its onset. For example, to achieve a state of OTS, the cyclist from the NFOR example described in the previous paragraph would likely have had one or more prior instances of NFOR in addition to a period of increased stress in his home, work, or team life or a physical issue such as an overuse injury or weakened immune system. Think of OTS as the perfect storm of overtraining that you never want to come near!

Although power monitors make direct quantification of training load possible, no hard and fast equation can state that a certain amount of work defines normal training, FOR, NFOR, or OTS. First, all cyclists differ in their ability to respond to a particular workload. Two cyclists riding an identical workout will respond differently based on their number of years in the sport, their particular phase of periodized training, and even their training for the previous day or week. Just as it is pointless to expect your body composition, weight, and resting heart rate to match someone else's, it is equally senseless to expect your potential for overtraining to be similar to another's. Therefore, an individual approach must be applied to training and addressing the possibility of OTS. Even when looking at a single cyclist, predicting the effect of a particular workload can be difficult because the nature of a periodized training plan generally means a wide fluctuation in workload throughout the year, making it hard to establish a baseline for workload or performance.

Heart Rate Monitors

With improved fitness, the defining change in your body is that your cardiac output, or the volume of blood pumped by your heart each minute, increases. Cardiac output is simply heart rate multiplied by stroke volume; the latter is the volume of blood pumped with each heart beat. In an untrained individual, the maximal cardiac output can reach approximately 25 liters per minute, but an elite aerobic athlete may have a value of 35 liters or higher. Obviously, as more blood is pumped, more oxygen is delivered to the muscles, increasing your aerobic energy production. Physiologically, what are some of the major adaptations in your cardiovascular system to enable this?

• Your maximal heart rate will not change with fitness. This value is largely determined by genetics and age.
• Overall blood volume will increase slightly, and some correlation is found between higher aerobic fitness and higher blood volume (Sawka et al. 1992). This result occurs mostly because of increased plasma volume rather than more red blood cells, such that hematocrit (the fraction of solid to liquid in blood) usually decreases with fitness.
• The heart, like your leg muscles, becomes stronger and able to pump blood with greater force. This increase in contractility helps to increase the stroke volume, or the amount of blood pumped with each heart beat.
• Stroke volume also increases by improvements in your body's ability to return blood from the body to the heart, resulting in greater filling of the heart each time.
• The capillary network in your muscles increases in density, permitting greater blood flow to the muscles themselves.

As can be seen from the preceding description, the cardiovascular system is a complex interplay of many things going on inside the body. Overall, the body adjusts the heart rate to achieve a cardiac output that will deliver adequate blood, oxygen, and nutrients to the muscles during exercise. Heart rate is also affected by the nervous system, as can be seen at the start line of a bicycle race when your heart rate is at 150 beats per minute before the starting gun even goes off! Or you could be tired and pushing yourself harder than ever, yet your heart rate reaches only 160 beats per minute as compared with your normal 175 beats per minute at threshold. In both cases, your nervous system is sending signals to your heart that override your body's physiological demands for cardiac output.

Therefore, although heart rate is an indication of effort, it is an indirect one at best. Similar to a tachometer on a car that tells you how fast the pistons are pumping rather than how many horsepower the engine is producing, heart rate does not tell you the speed or power that you are generating on the bike, but only how fast the heart is pumping. Hunter likes to say that “heart rate tells me the ‘intensity of an athlete's intention,' and that can help me to better understand the athlete in workouts and races.” Also, heart rate can be influenced by many factors related and not related to exercise, such as sleep, caffeine intake, and hydration status. That being said, monitoring your heart rate is beneficial, and you can track fitness changes over time by comparing heart rate with the data channels.

Standing Versus Seated Pedaling

The first and most obvious weight-bearing exercise is running. A lot of energy is required not only to propel yourself forward but also to keep yourself upright and stable. Added to that is the impact force from landing on your feet with each stride. The combination of the two makes for a much higher heart rate, a greater metabolic rate, and more overall stress when running compared with cycling. Cycling is mostly a non-weight-bearing activity, and the bicycle is a highly efficient machine because it removes the impact forces and cradles your body in a position that greatly minimizes the need to support your body weight. But at times you have to stand when riding, and then you have to support a good deal of your body weight (figure 8.8). Whether it's on the flats, in the hills, or in a sprint, you are no longer supporting your weight on the saddle, and you have to rely on your muscles more to keep yourself upright.

Of course, standing typically requires more energy and makes you less economical, but it also leverages more of your body weight over the pedals and recruits additional muscles, thus making higher power output possible. For this reason, we're generally taught to keep the standing to a minimum and to stand only when we need extra power, such as when initiating an acceleration (e.g., sprint, breakaway) or when we need extra power while climbing. Wind resistance is also higher while standing because of the larger surface area exposed.

Millet et al. (2002) tested fit elite and pro cyclists riding for 6 minutes at 75 percent of V?O2max in a velodrome and while seated or standing on a 5.3 percent gradient hill. The cyclists also performed 30-second all-out sprints in the lab and while seated and standing on a gradual hill. Thanks to the improvements in technology, the researchers could take this study out into real terrain and use the subjects' own SRM-equipped bikes with portable gas analyzers, increasing the applicability of the study. As expected, heart rate was about eight beats per minute higher when standing compared with seated uphill. Ventilation was also higher, although no differences were seen in oxygen consumption. Cadence was similar at just under 60 revolutions per minute in both conditions. Most important, no differences were found in either gross efficiency (about 22.5 percent) or economy (4.7 kilojoules of power per liter of oxygen). In the 30-second tests, maximum and mean power were much higher in the standing position compared with the seated position (mean power of about 820 and 650 watts, respectively), despite similar cadences and blood lactate values.

Overall, the ability to produce higher power when sprinting and standing is obvious and intuitive, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, especially the finding that no differences occur in efficiency or economy whether standing or seated. This result means that, although standing creates more stress on the aerobic and cardiovascular system, it does not necessarily cause a decrease in efficiency itself. So standing is not going to cost more energy to perform when you factor in the greater power that you are generating. One obvious caveat is that extended standing while climbing must be practiced to optimize economy. Another caveat is that all the subjects in the study were young, lean, and light, averaging 67 kilograms. For bigger riders with more weight to support, the efficiency and economy equations might be tilted in favor of sitting.

Because overtraining affects the physical responses to training and adaptation, the body must also contend with a wide array of psychosocial stressors, from sports-related (team dynamics, coaches) and environmental (frequent travel, altitude) challenges to personal (relationship, work, financial) issues. Given the multitude of potential contributing factors beyond the quantification of training load, isolating the direct cause of overtraining can be difficult. The primary determinant is likely different for each cyclist. For example, a masters cyclist who juggles training time with a demanding job and a young family may overtrain from an inability to manage these multiple responsibilities. Alternately, a keen junior cyclist just starting in the sport may overtrain from trying to ride too much too soon or may develop overuse injuries from riding overlarge gears. Therefore, the social context of the cyclist must be carefully considered in managing overtraining. In addition, underlying medical issues may predispose (e.g., history of depression) or directly contribute (e.g., injury) to the onset of OTS.

Stages of Overtraining

The principle of overload is fundamental to the process of improving fitness (McNicol et al. 2009). A period of stress followed by recovery results in a “supercompensation” in which the body adapts to the imposed stress and becomes stronger, thus improving performance. The human body is highly adaptable to the stresses imposed on it as long as the stress is not excessive.

The European College of Sport Science, in its 2006 position stand (Meeusen et al. 2006), presented overtraining as a continuum from the desired “normal” and functional overload and functional overreaching (FOR), through to nonfunctional overreaching (NFOR), and ultimately to overtraining syndrome (OTS) and burnout. Although this representation is possibly an oversimplification—debate continues about whether the process of overtraining is a continuum or a series of distinct and independent phases—having standardized definitions as a basis of discussion is helpful.

• Training. A process of overload that is used to disturb the body's normal state of fitness, which results in acute fatigue (one to two days at most), adaptation by the body, and ultimately an improvement in performance. This level of training is what we do most of the time, such as a few hard interval sessions followed by a day or two of easier rides over the course of a week, or two to three weeks of progressive overload followed by a recovery week of reduced training to permit the body to adapt to the stress.
• Overtraining. Within this paradigm, overtraining is used to describe a period in which greater than normal training stress is imposed. An example may be suddenly spending two weeks doing more and harder intervals than you have been used to doing or spending a week at an intense climbing camp in the mountains, where you put in long hours and do lots of hard climbing. As explained in the three definitions that follow, overtraining can be a normal and positive process of overload and supercompensation (see functional overreaching), or it can become a negative stimulus that is more than the cyclist can handle (see nonfunctional overreaching and overtraining syndrome).
• Functional overreaching (FOR). A process in which overtraining, possibly followed by a temporary drop-off in performance lasting days to at most several weeks, results in the body adapting by becoming stronger and thus being able to produce performances that exceed the previous baseline. A critical component of FOR is a period of adequate recovery following the period of overtraining. An example may be a cyclist who spends a week at a climbing camp in the mountains, recovers at home with an easy week, and then settles back into a more normal training program during which he sees his overall riding level improve.
• Nonfunctional overreaching (NFOR). An extreme level of overtraining, often associated with inadequate recovery, in which the drop-off in performance after a period of overload is prolonged and performance stagnates or remains at baseline or lower for weeks or even months. Besides causing physiological changes, this state is often accompanied by psychological disturbances such as irritability, increased fatigue, and decreased vigor. Hormonal disturbances also are more likely within this phase. For example, NFOR might occur if the cyclist returned from a week at the climbing camp and then, without taking a recovery period, continued to push his body by doing a few additional weeks of hard training, thinking that by doing so he could take advantage of his newfound fitness and motivation to reap even greater benefits. With sufficient rest, cyclists in NFOR typically recover over a period of several months.
• Overtraining syndrome (OTS). An extreme level of overtraining, in which performance becomes impaired for many months to years. A host of psychological and physiological impairments can be present, and cyclists who reach this level often burn out completely and quit the sport. In general, rarely does physical stress alone bring about a state of OTS. Rather, the use of the term syndrome is intentional in recognition of the numerous factors that may contribute to its onset. For example, to achieve a state of OTS, the cyclist from the NFOR example described in the previous paragraph would likely have had one or more prior instances of NFOR in addition to a period of increased stress in his home, work, or team life or a physical issue such as an overuse injury or weakened immune system. Think of OTS as the perfect storm of overtraining that you never want to come near!

Although power monitors make direct quantification of training load possible, no hard and fast equation can state that a certain amount of work defines normal training, FOR, NFOR, or OTS. First, all cyclists differ in their ability to respond to a particular workload. Two cyclists riding an identical workout will respond differently based on their number of years in the sport, their particular phase of periodized training, and even their training for the previous day or week. Just as it is pointless to expect your body composition, weight, and resting heart rate to match someone else's, it is equally senseless to expect your potential for overtraining to be similar to another's. Therefore, an individual approach must be applied to training and addressing the possibility of OTS. Even when looking at a single cyclist, predicting the effect of a particular workload can be difficult because the nature of a periodized training plan generally means a wide fluctuation in workload throughout the year, making it hard to establish a baseline for workload or performance.

Heart Rate Monitors

With improved fitness, the defining change in your body is that your cardiac output, or the volume of blood pumped by your heart each minute, increases. Cardiac output is simply heart rate multiplied by stroke volume; the latter is the volume of blood pumped with each heart beat. In an untrained individual, the maximal cardiac output can reach approximately 25 liters per minute, but an elite aerobic athlete may have a value of 35 liters or higher. Obviously, as more blood is pumped, more oxygen is delivered to the muscles, increasing your aerobic energy production. Physiologically, what are some of the major adaptations in your cardiovascular system to enable this?

• Your maximal heart rate will not change with fitness. This value is largely determined by genetics and age.
• Overall blood volume will increase slightly, and some correlation is found between higher aerobic fitness and higher blood volume (Sawka et al. 1992). This result occurs mostly because of increased plasma volume rather than more red blood cells, such that hematocrit (the fraction of solid to liquid in blood) usually decreases with fitness.
• The heart, like your leg muscles, becomes stronger and able to pump blood with greater force. This increase in contractility helps to increase the stroke volume, or the amount of blood pumped with each heart beat.
• Stroke volume also increases by improvements in your body's ability to return blood from the body to the heart, resulting in greater filling of the heart each time.
• The capillary network in your muscles increases in density, permitting greater blood flow to the muscles themselves.

As can be seen from the preceding description, the cardiovascular system is a complex interplay of many things going on inside the body. Overall, the body adjusts the heart rate to achieve a cardiac output that will deliver adequate blood, oxygen, and nutrients to the muscles during exercise. Heart rate is also affected by the nervous system, as can be seen at the start line of a bicycle race when your heart rate is at 150 beats per minute before the starting gun even goes off! Or you could be tired and pushing yourself harder than ever, yet your heart rate reaches only 160 beats per minute as compared with your normal 175 beats per minute at threshold. In both cases, your nervous system is sending signals to your heart that override your body's physiological demands for cardiac output.

Therefore, although heart rate is an indication of effort, it is an indirect one at best. Similar to a tachometer on a car that tells you how fast the pistons are pumping rather than how many horsepower the engine is producing, heart rate does not tell you the speed or power that you are generating on the bike, but only how fast the heart is pumping. Hunter likes to say that “heart rate tells me the ‘intensity of an athlete's intention,' and that can help me to better understand the athlete in workouts and races.” Also, heart rate can be influenced by many factors related and not related to exercise, such as sleep, caffeine intake, and hydration status. That being said, monitoring your heart rate is beneficial, and you can track fitness changes over time by comparing heart rate with the data channels.

Standing Versus Seated Pedaling

The first and most obvious weight-bearing exercise is running. A lot of energy is required not only to propel yourself forward but also to keep yourself upright and stable. Added to that is the impact force from landing on your feet with each stride. The combination of the two makes for a much higher heart rate, a greater metabolic rate, and more overall stress when running compared with cycling. Cycling is mostly a non-weight-bearing activity, and the bicycle is a highly efficient machine because it removes the impact forces and cradles your body in a position that greatly minimizes the need to support your body weight. But at times you have to stand when riding, and then you have to support a good deal of your body weight (figure 8.8). Whether it's on the flats, in the hills, or in a sprint, you are no longer supporting your weight on the saddle, and you have to rely on your muscles more to keep yourself upright.

Of course, standing typically requires more energy and makes you less economical, but it also leverages more of your body weight over the pedals and recruits additional muscles, thus making higher power output possible. For this reason, we're generally taught to keep the standing to a minimum and to stand only when we need extra power, such as when initiating an acceleration (e.g., sprint, breakaway) or when we need extra power while climbing. Wind resistance is also higher while standing because of the larger surface area exposed.

Millet et al. (2002) tested fit elite and pro cyclists riding for 6 minutes at 75 percent of V?O2max in a velodrome and while seated or standing on a 5.3 percent gradient hill. The cyclists also performed 30-second all-out sprints in the lab and while seated and standing on a gradual hill. Thanks to the improvements in technology, the researchers could take this study out into real terrain and use the subjects' own SRM-equipped bikes with portable gas analyzers, increasing the applicability of the study. As expected, heart rate was about eight beats per minute higher when standing compared with seated uphill. Ventilation was also higher, although no differences were seen in oxygen consumption. Cadence was similar at just under 60 revolutions per minute in both conditions. Most important, no differences were found in either gross efficiency (about 22.5 percent) or economy (4.7 kilojoules of power per liter of oxygen). In the 30-second tests, maximum and mean power were much higher in the standing position compared with the seated position (mean power of about 820 and 650 watts, respectively), despite similar cadences and blood lactate values.

Overall, the ability to produce higher power when sprinting and standing is obvious and intuitive, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, especially the finding that no differences occur in efficiency or economy whether standing or seated. This result means that, although standing creates more stress on the aerobic and cardiovascular system, it does not necessarily cause a decrease in efficiency itself. So standing is not going to cost more energy to perform when you factor in the greater power that you are generating. One obvious caveat is that extended standing while climbing must be practiced to optimize economy. Another caveat is that all the subjects in the study were young, lean, and light, averaging 67 kilograms. For bigger riders with more weight to support, the efficiency and economy equations might be tilted in favor of sitting.

Because overtraining affects the physical responses to training and adaptation, the body must also contend with a wide array of psychosocial stressors, from sports-related (team dynamics, coaches) and environmental (frequent travel, altitude) challenges to personal (relationship, work, financial) issues. Given the multitude of potential contributing factors beyond the quantification of training load, isolating the direct cause of overtraining can be difficult. The primary determinant is likely different for each cyclist. For example, a masters cyclist who juggles training time with a demanding job and a young family may overtrain from an inability to manage these multiple responsibilities. Alternately, a keen junior cyclist just starting in the sport may overtrain from trying to ride too much too soon or may develop overuse injuries from riding overlarge gears. Therefore, the social context of the cyclist must be carefully considered in managing overtraining. In addition, underlying medical issues may predispose (e.g., history of depression) or directly contribute (e.g., injury) to the onset of OTS.

Stages of Overtraining

The principle of overload is fundamental to the process of improving fitness (McNicol et al. 2009). A period of stress followed by recovery results in a “supercompensation” in which the body adapts to the imposed stress and becomes stronger, thus improving performance. The human body is highly adaptable to the stresses imposed on it as long as the stress is not excessive.

The European College of Sport Science, in its 2006 position stand (Meeusen et al. 2006), presented overtraining as a continuum from the desired “normal” and functional overload and functional overreaching (FOR), through to nonfunctional overreaching (NFOR), and ultimately to overtraining syndrome (OTS) and burnout. Although this representation is possibly an oversimplification—debate continues about whether the process of overtraining is a continuum or a series of distinct and independent phases—having standardized definitions as a basis of discussion is helpful.

• Training. A process of overload that is used to disturb the body's normal state of fitness, which results in acute fatigue (one to two days at most), adaptation by the body, and ultimately an improvement in performance. This level of training is what we do most of the time, such as a few hard interval sessions followed by a day or two of easier rides over the course of a week, or two to three weeks of progressive overload followed by a recovery week of reduced training to permit the body to adapt to the stress.
• Overtraining. Within this paradigm, overtraining is used to describe a period in which greater than normal training stress is imposed. An example may be suddenly spending two weeks doing more and harder intervals than you have been used to doing or spending a week at an intense climbing camp in the mountains, where you put in long hours and do lots of hard climbing. As explained in the three definitions that follow, overtraining can be a normal and positive process of overload and supercompensation (see functional overreaching), or it can become a negative stimulus that is more than the cyclist can handle (see nonfunctional overreaching and overtraining syndrome).
• Functional overreaching (FOR). A process in which overtraining, possibly followed by a temporary drop-off in performance lasting days to at most several weeks, results in the body adapting by becoming stronger and thus being able to produce performances that exceed the previous baseline. A critical component of FOR is a period of adequate recovery following the period of overtraining. An example may be a cyclist who spends a week at a climbing camp in the mountains, recovers at home with an easy week, and then settles back into a more normal training program during which he sees his overall riding level improve.
• Nonfunctional overreaching (NFOR). An extreme level of overtraining, often associated with inadequate recovery, in which the drop-off in performance after a period of overload is prolonged and performance stagnates or remains at baseline or lower for weeks or even months. Besides causing physiological changes, this state is often accompanied by psychological disturbances such as irritability, increased fatigue, and decreased vigor. Hormonal disturbances also are more likely within this phase. For example, NFOR might occur if the cyclist returned from a week at the climbing camp and then, without taking a recovery period, continued to push his body by doing a few additional weeks of hard training, thinking that by doing so he could take advantage of his newfound fitness and motivation to reap even greater benefits. With sufficient rest, cyclists in NFOR typically recover over a period of several months.
• Overtraining syndrome (OTS). An extreme level of overtraining, in which performance becomes impaired for many months to years. A host of psychological and physiological impairments can be present, and cyclists who reach this level often burn out completely and quit the sport. In general, rarely does physical stress alone bring about a state of OTS. Rather, the use of the term syndrome is intentional in recognition of the numerous factors that may contribute to its onset. For example, to achieve a state of OTS, the cyclist from the NFOR example described in the previous paragraph would likely have had one or more prior instances of NFOR in addition to a period of increased stress in his home, work, or team life or a physical issue such as an overuse injury or weakened immune system. Think of OTS as the perfect storm of overtraining that you never want to come near!

Although power monitors make direct quantification of training load possible, no hard and fast equation can state that a certain amount of work defines normal training, FOR, NFOR, or OTS. First, all cyclists differ in their ability to respond to a particular workload. Two cyclists riding an identical workout will respond differently based on their number of years in the sport, their particular phase of periodized training, and even their training for the previous day or week. Just as it is pointless to expect your body composition, weight, and resting heart rate to match someone else's, it is equally senseless to expect your potential for overtraining to be similar to another's. Therefore, an individual approach must be applied to training and addressing the possibility of OTS. Even when looking at a single cyclist, predicting the effect of a particular workload can be difficult because the nature of a periodized training plan generally means a wide fluctuation in workload throughout the year, making it hard to establish a baseline for workload or performance.

Heart Rate Monitors

With improved fitness, the defining change in your body is that your cardiac output, or the volume of blood pumped by your heart each minute, increases. Cardiac output is simply heart rate multiplied by stroke volume; the latter is the volume of blood pumped with each heart beat. In an untrained individual, the maximal cardiac output can reach approximately 25 liters per minute, but an elite aerobic athlete may have a value of 35 liters or higher. Obviously, as more blood is pumped, more oxygen is delivered to the muscles, increasing your aerobic energy production. Physiologically, what are some of the major adaptations in your cardiovascular system to enable this?

• Your maximal heart rate will not change with fitness. This value is largely determined by genetics and age.
• Overall blood volume will increase slightly, and some correlation is found between higher aerobic fitness and higher blood volume (Sawka et al. 1992). This result occurs mostly because of increased plasma volume rather than more red blood cells, such that hematocrit (the fraction of solid to liquid in blood) usually decreases with fitness.
• The heart, like your leg muscles, becomes stronger and able to pump blood with greater force. This increase in contractility helps to increase the stroke volume, or the amount of blood pumped with each heart beat.
• Stroke volume also increases by improvements in your body's ability to return blood from the body to the heart, resulting in greater filling of the heart each time.
• The capillary network in your muscles increases in density, permitting greater blood flow to the muscles themselves.

As can be seen from the preceding description, the cardiovascular system is a complex interplay of many things going on inside the body. Overall, the body adjusts the heart rate to achieve a cardiac output that will deliver adequate blood, oxygen, and nutrients to the muscles during exercise. Heart rate is also affected by the nervous system, as can be seen at the start line of a bicycle race when your heart rate is at 150 beats per minute before the starting gun even goes off! Or you could be tired and pushing yourself harder than ever, yet your heart rate reaches only 160 beats per minute as compared with your normal 175 beats per minute at threshold. In both cases, your nervous system is sending signals to your heart that override your body's physiological demands for cardiac output.

Therefore, although heart rate is an indication of effort, it is an indirect one at best. Similar to a tachometer on a car that tells you how fast the pistons are pumping rather than how many horsepower the engine is producing, heart rate does not tell you the speed or power that you are generating on the bike, but only how fast the heart is pumping. Hunter likes to say that “heart rate tells me the ‘intensity of an athlete's intention,' and that can help me to better understand the athlete in workouts and races.” Also, heart rate can be influenced by many factors related and not related to exercise, such as sleep, caffeine intake, and hydration status. That being said, monitoring your heart rate is beneficial, and you can track fitness changes over time by comparing heart rate with the data channels.

Standing Versus Seated Pedaling

The first and most obvious weight-bearing exercise is running. A lot of energy is required not only to propel yourself forward but also to keep yourself upright and stable. Added to that is the impact force from landing on your feet with each stride. The combination of the two makes for a much higher heart rate, a greater metabolic rate, and more overall stress when running compared with cycling. Cycling is mostly a non-weight-bearing activity, and the bicycle is a highly efficient machine because it removes the impact forces and cradles your body in a position that greatly minimizes the need to support your body weight. But at times you have to stand when riding, and then you have to support a good deal of your body weight (figure 8.8). Whether it's on the flats, in the hills, or in a sprint, you are no longer supporting your weight on the saddle, and you have to rely on your muscles more to keep yourself upright.

Of course, standing typically requires more energy and makes you less economical, but it also leverages more of your body weight over the pedals and recruits additional muscles, thus making higher power output possible. For this reason, we're generally taught to keep the standing to a minimum and to stand only when we need extra power, such as when initiating an acceleration (e.g., sprint, breakaway) or when we need extra power while climbing. Wind resistance is also higher while standing because of the larger surface area exposed.

Millet et al. (2002) tested fit elite and pro cyclists riding for 6 minutes at 75 percent of V?O2max in a velodrome and while seated or standing on a 5.3 percent gradient hill. The cyclists also performed 30-second all-out sprints in the lab and while seated and standing on a gradual hill. Thanks to the improvements in technology, the researchers could take this study out into real terrain and use the subjects' own SRM-equipped bikes with portable gas analyzers, increasing the applicability of the study. As expected, heart rate was about eight beats per minute higher when standing compared with seated uphill. Ventilation was also higher, although no differences were seen in oxygen consumption. Cadence was similar at just under 60 revolutions per minute in both conditions. Most important, no differences were found in either gross efficiency (about 22.5 percent) or economy (4.7 kilojoules of power per liter of oxygen). In the 30-second tests, maximum and mean power were much higher in the standing position compared with the seated position (mean power of about 820 and 650 watts, respectively), despite similar cadences and blood lactate values.

Overall, the ability to produce higher power when sprinting and standing is obvious and intuitive, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, especially the finding that no differences occur in efficiency or economy whether standing or seated. This result means that, although standing creates more stress on the aerobic and cardiovascular system, it does not necessarily cause a decrease in efficiency itself. So standing is not going to cost more energy to perform when you factor in the greater power that you are generating. One obvious caveat is that extended standing while climbing must be practiced to optimize economy. Another caveat is that all the subjects in the study were young, lean, and light, averaging 67 kilograms. For bigger riders with more weight to support, the efficiency and economy equations might be tilted in favor of sitting.

Because overtraining affects the physical responses to training and adaptation, the body must also contend with a wide array of psychosocial stressors, from sports-related (team dynamics, coaches) and environmental (frequent travel, altitude) challenges to personal (relationship, work, financial) issues. Given the multitude of potential contributing factors beyond the quantification of training load, isolating the direct cause of overtraining can be difficult. The primary determinant is likely different for each cyclist. For example, a masters cyclist who juggles training time with a demanding job and a young family may overtrain from an inability to manage these multiple responsibilities. Alternately, a keen junior cyclist just starting in the sport may overtrain from trying to ride too much too soon or may develop overuse injuries from riding overlarge gears. Therefore, the social context of the cyclist must be carefully considered in managing overtraining. In addition, underlying medical issues may predispose (e.g., history of depression) or directly contribute (e.g., injury) to the onset of OTS.

Stages of Overtraining

The principle of overload is fundamental to the process of improving fitness (McNicol et al. 2009). A period of stress followed by recovery results in a “supercompensation” in which the body adapts to the imposed stress and becomes stronger, thus improving performance. The human body is highly adaptable to the stresses imposed on it as long as the stress is not excessive.

The European College of Sport Science, in its 2006 position stand (Meeusen et al. 2006), presented overtraining as a continuum from the desired “normal” and functional overload and functional overreaching (FOR), through to nonfunctional overreaching (NFOR), and ultimately to overtraining syndrome (OTS) and burnout. Although this representation is possibly an oversimplification—debate continues about whether the process of overtraining is a continuum or a series of distinct and independent phases—having standardized definitions as a basis of discussion is helpful.

• Training. A process of overload that is used to disturb the body's normal state of fitness, which results in acute fatigue (one to two days at most), adaptation by the body, and ultimately an improvement in performance. This level of training is what we do most of the time, such as a few hard interval sessions followed by a day or two of easier rides over the course of a week, or two to three weeks of progressive overload followed by a recovery week of reduced training to permit the body to adapt to the stress.
• Overtraining. Within this paradigm, overtraining is used to describe a period in which greater than normal training stress is imposed. An example may be suddenly spending two weeks doing more and harder intervals than you have been used to doing or spending a week at an intense climbing camp in the mountains, where you put in long hours and do lots of hard climbing. As explained in the three definitions that follow, overtraining can be a normal and positive process of overload and supercompensation (see functional overreaching), or it can become a negative stimulus that is more than the cyclist can handle (see nonfunctional overreaching and overtraining syndrome).
• Functional overreaching (FOR). A process in which overtraining, possibly followed by a temporary drop-off in performance lasting days to at most several weeks, results in the body adapting by becoming stronger and thus being able to produce performances that exceed the previous baseline. A critical component of FOR is a period of adequate recovery following the period of overtraining. An example may be a cyclist who spends a week at a climbing camp in the mountains, recovers at home with an easy week, and then settles back into a more normal training program during which he sees his overall riding level improve.
• Nonfunctional overreaching (NFOR). An extreme level of overtraining, often associated with inadequate recovery, in which the drop-off in performance after a period of overload is prolonged and performance stagnates or remains at baseline or lower for weeks or even months. Besides causing physiological changes, this state is often accompanied by psychological disturbances such as irritability, increased fatigue, and decreased vigor. Hormonal disturbances also are more likely within this phase. For example, NFOR might occur if the cyclist returned from a week at the climbing camp and then, without taking a recovery period, continued to push his body by doing a few additional weeks of hard training, thinking that by doing so he could take advantage of his newfound fitness and motivation to reap even greater benefits. With sufficient rest, cyclists in NFOR typically recover over a period of several months.
• Overtraining syndrome (OTS). An extreme level of overtraining, in which performance becomes impaired for many months to years. A host of psychological and physiological impairments can be present, and cyclists who reach this level often burn out completely and quit the sport. In general, rarely does physical stress alone bring about a state of OTS. Rather, the use of the term syndrome is intentional in recognition of the numerous factors that may contribute to its onset. For example, to achieve a state of OTS, the cyclist from the NFOR example described in the previous paragraph would likely have had one or more prior instances of NFOR in addition to a period of increased stress in his home, work, or team life or a physical issue such as an overuse injury or weakened immune system. Think of OTS as the perfect storm of overtraining that you never want to come near!

Although power monitors make direct quantification of training load possible, no hard and fast equation can state that a certain amount of work defines normal training, FOR, NFOR, or OTS. First, all cyclists differ in their ability to respond to a particular workload. Two cyclists riding an identical workout will respond differently based on their number of years in the sport, their particular phase of periodized training, and even their training for the previous day or week. Just as it is pointless to expect your body composition, weight, and resting heart rate to match someone else's, it is equally senseless to expect your potential for overtraining to be similar to another's. Therefore, an individual approach must be applied to training and addressing the possibility of OTS. Even when looking at a single cyclist, predicting the effect of a particular workload can be difficult because the nature of a periodized training plan generally means a wide fluctuation in workload throughout the year, making it hard to establish a baseline for workload or performance.

Heart Rate Monitors

With improved fitness, the defining change in your body is that your cardiac output, or the volume of blood pumped by your heart each minute, increases. Cardiac output is simply heart rate multiplied by stroke volume; the latter is the volume of blood pumped with each heart beat. In an untrained individual, the maximal cardiac output can reach approximately 25 liters per minute, but an elite aerobic athlete may have a value of 35 liters or higher. Obviously, as more blood is pumped, more oxygen is delivered to the muscles, increasing your aerobic energy production. Physiologically, what are some of the major adaptations in your cardiovascular system to enable this?

• Your maximal heart rate will not change with fitness. This value is largely determined by genetics and age.
• Overall blood volume will increase slightly, and some correlation is found between higher aerobic fitness and higher blood volume (Sawka et al. 1992). This result occurs mostly because of increased plasma volume rather than more red blood cells, such that hematocrit (the fraction of solid to liquid in blood) usually decreases with fitness.
• The heart, like your leg muscles, becomes stronger and able to pump blood with greater force. This increase in contractility helps to increase the stroke volume, or the amount of blood pumped with each heart beat.
• Stroke volume also increases by improvements in your body's ability to return blood from the body to the heart, resulting in greater filling of the heart each time.
• The capillary network in your muscles increases in density, permitting greater blood flow to the muscles themselves.

As can be seen from the preceding description, the cardiovascular system is a complex interplay of many things going on inside the body. Overall, the body adjusts the heart rate to achieve a cardiac output that will deliver adequate blood, oxygen, and nutrients to the muscles during exercise. Heart rate is also affected by the nervous system, as can be seen at the start line of a bicycle race when your heart rate is at 150 beats per minute before the starting gun even goes off! Or you could be tired and pushing yourself harder than ever, yet your heart rate reaches only 160 beats per minute as compared with your normal 175 beats per minute at threshold. In both cases, your nervous system is sending signals to your heart that override your body's physiological demands for cardiac output.

Therefore, although heart rate is an indication of effort, it is an indirect one at best. Similar to a tachometer on a car that tells you how fast the pistons are pumping rather than how many horsepower the engine is producing, heart rate does not tell you the speed or power that you are generating on the bike, but only how fast the heart is pumping. Hunter likes to say that “heart rate tells me the ‘intensity of an athlete's intention,' and that can help me to better understand the athlete in workouts and races.” Also, heart rate can be influenced by many factors related and not related to exercise, such as sleep, caffeine intake, and hydration status. That being said, monitoring your heart rate is beneficial, and you can track fitness changes over time by comparing heart rate with the data channels.

Standing Versus Seated Pedaling

The first and most obvious weight-bearing exercise is running. A lot of energy is required not only to propel yourself forward but also to keep yourself upright and stable. Added to that is the impact force from landing on your feet with each stride. The combination of the two makes for a much higher heart rate, a greater metabolic rate, and more overall stress when running compared with cycling. Cycling is mostly a non-weight-bearing activity, and the bicycle is a highly efficient machine because it removes the impact forces and cradles your body in a position that greatly minimizes the need to support your body weight. But at times you have to stand when riding, and then you have to support a good deal of your body weight (figure 8.8). Whether it's on the flats, in the hills, or in a sprint, you are no longer supporting your weight on the saddle, and you have to rely on your muscles more to keep yourself upright.

Of course, standing typically requires more energy and makes you less economical, but it also leverages more of your body weight over the pedals and recruits additional muscles, thus making higher power output possible. For this reason, we're generally taught to keep the standing to a minimum and to stand only when we need extra power, such as when initiating an acceleration (e.g., sprint, breakaway) or when we need extra power while climbing. Wind resistance is also higher while standing because of the larger surface area exposed.

Millet et al. (2002) tested fit elite and pro cyclists riding for 6 minutes at 75 percent of V?O2max in a velodrome and while seated or standing on a 5.3 percent gradient hill. The cyclists also performed 30-second all-out sprints in the lab and while seated and standing on a gradual hill. Thanks to the improvements in technology, the researchers could take this study out into real terrain and use the subjects' own SRM-equipped bikes with portable gas analyzers, increasing the applicability of the study. As expected, heart rate was about eight beats per minute higher when standing compared with seated uphill. Ventilation was also higher, although no differences were seen in oxygen consumption. Cadence was similar at just under 60 revolutions per minute in both conditions. Most important, no differences were found in either gross efficiency (about 22.5 percent) or economy (4.7 kilojoules of power per liter of oxygen). In the 30-second tests, maximum and mean power were much higher in the standing position compared with the seated position (mean power of about 820 and 650 watts, respectively), despite similar cadences and blood lactate values.

Overall, the ability to produce higher power when sprinting and standing is obvious and intuitive, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, especially the finding that no differences occur in efficiency or economy whether standing or seated. This result means that, although standing creates more stress on the aerobic and cardiovascular system, it does not necessarily cause a decrease in efficiency itself. So standing is not going to cost more energy to perform when you factor in the greater power that you are generating. One obvious caveat is that extended standing while climbing must be practiced to optimize economy. Another caveat is that all the subjects in the study were young, lean, and light, averaging 67 kilograms. For bigger riders with more weight to support, the efficiency and economy equations might be tilted in favor of sitting.

Because overtraining affects the physical responses to training and adaptation, the body must also contend with a wide array of psychosocial stressors, from sports-related (team dynamics, coaches) and environmental (frequent travel, altitude) challenges to personal (relationship, work, financial) issues. Given the multitude of potential contributing factors beyond the quantification of training load, isolating the direct cause of overtraining can be difficult. The primary determinant is likely different for each cyclist. For example, a masters cyclist who juggles training time with a demanding job and a young family may overtrain from an inability to manage these multiple responsibilities. Alternately, a keen junior cyclist just starting in the sport may overtrain from trying to ride too much too soon or may develop overuse injuries from riding overlarge gears. Therefore, the social context of the cyclist must be carefully considered in managing overtraining. In addition, underlying medical issues may predispose (e.g., history of depression) or directly contribute (e.g., injury) to the onset of OTS.

Stages of Overtraining

The principle of overload is fundamental to the process of improving fitness (McNicol et al. 2009). A period of stress followed by recovery results in a “supercompensation” in which the body adapts to the imposed stress and becomes stronger, thus improving performance. The human body is highly adaptable to the stresses imposed on it as long as the stress is not excessive.

The European College of Sport Science, in its 2006 position stand (Meeusen et al. 2006), presented overtraining as a continuum from the desired “normal” and functional overload and functional overreaching (FOR), through to nonfunctional overreaching (NFOR), and ultimately to overtraining syndrome (OTS) and burnout. Although this representation is possibly an oversimplification—debate continues about whether the process of overtraining is a continuum or a series of distinct and independent phases—having standardized definitions as a basis of discussion is helpful.

• Training. A process of overload that is used to disturb the body's normal state of fitness, which results in acute fatigue (one to two days at most), adaptation by the body, and ultimately an improvement in performance. This level of training is what we do most of the time, such as a few hard interval sessions followed by a day or two of easier rides over the course of a week, or two to three weeks of progressive overload followed by a recovery week of reduced training to permit the body to adapt to the stress.
• Overtraining. Within this paradigm, overtraining is used to describe a period in which greater than normal training stress is imposed. An example may be suddenly spending two weeks doing more and harder intervals than you have been used to doing or spending a week at an intense climbing camp in the mountains, where you put in long hours and do lots of hard climbing. As explained in the three definitions that follow, overtraining can be a normal and positive process of overload and supercompensation (see functional overreaching), or it can become a negative stimulus that is more than the cyclist can handle (see nonfunctional overreaching and overtraining syndrome).
• Functional overreaching (FOR). A process in which overtraining, possibly followed by a temporary drop-off in performance lasting days to at most several weeks, results in the body adapting by becoming stronger and thus being able to produce performances that exceed the previous baseline. A critical component of FOR is a period of adequate recovery following the period of overtraining. An example may be a cyclist who spends a week at a climbing camp in the mountains, recovers at home with an easy week, and then settles back into a more normal training program during which he sees his overall riding level improve.
• Nonfunctional overreaching (NFOR). An extreme level of overtraining, often associated with inadequate recovery, in which the drop-off in performance after a period of overload is prolonged and performance stagnates or remains at baseline or lower for weeks or even months. Besides causing physiological changes, this state is often accompanied by psychological disturbances such as irritability, increased fatigue, and decreased vigor. Hormonal disturbances also are more likely within this phase. For example, NFOR might occur if the cyclist returned from a week at the climbing camp and then, without taking a recovery period, continued to push his body by doing a few additional weeks of hard training, thinking that by doing so he could take advantage of his newfound fitness and motivation to reap even greater benefits. With sufficient rest, cyclists in NFOR typically recover over a period of several months.
• Overtraining syndrome (OTS). An extreme level of overtraining, in which performance becomes impaired for many months to years. A host of psychological and physiological impairments can be present, and cyclists who reach this level often burn out completely and quit the sport. In general, rarely does physical stress alone bring about a state of OTS. Rather, the use of the term syndrome is intentional in recognition of the numerous factors that may contribute to its onset. For example, to achieve a state of OTS, the cyclist from the NFOR example described in the previous paragraph would likely have had one or more prior instances of NFOR in addition to a period of increased stress in his home, work, or team life or a physical issue such as an overuse injury or weakened immune system. Think of OTS as the perfect storm of overtraining that you never want to come near!

Although power monitors make direct quantification of training load possible, no hard and fast equation can state that a certain amount of work defines normal training, FOR, NFOR, or OTS. First, all cyclists differ in their ability to respond to a particular workload. Two cyclists riding an identical workout will respond differently based on their number of years in the sport, their particular phase of periodized training, and even their training for the previous day or week. Just as it is pointless to expect your body composition, weight, and resting heart rate to match someone else's, it is equally senseless to expect your potential for overtraining to be similar to another's. Therefore, an individual approach must be applied to training and addressing the possibility of OTS. Even when looking at a single cyclist, predicting the effect of a particular workload can be difficult because the nature of a periodized training plan generally means a wide fluctuation in workload throughout the year, making it hard to establish a baseline for workload or performance.

Heart Rate Monitors

With improved fitness, the defining change in your body is that your cardiac output, or the volume of blood pumped by your heart each minute, increases. Cardiac output is simply heart rate multiplied by stroke volume; the latter is the volume of blood pumped with each heart beat. In an untrained individual, the maximal cardiac output can reach approximately 25 liters per minute, but an elite aerobic athlete may have a value of 35 liters or higher. Obviously, as more blood is pumped, more oxygen is delivered to the muscles, increasing your aerobic energy production. Physiologically, what are some of the major adaptations in your cardiovascular system to enable this?

• Your maximal heart rate will not change with fitness. This value is largely determined by genetics and age.
• Overall blood volume will increase slightly, and some correlation is found between higher aerobic fitness and higher blood volume (Sawka et al. 1992). This result occurs mostly because of increased plasma volume rather than more red blood cells, such that hematocrit (the fraction of solid to liquid in blood) usually decreases with fitness.
• The heart, like your leg muscles, becomes stronger and able to pump blood with greater force. This increase in contractility helps to increase the stroke volume, or the amount of blood pumped with each heart beat.
• Stroke volume also increases by improvements in your body's ability to return blood from the body to the heart, resulting in greater filling of the heart each time.
• The capillary network in your muscles increases in density, permitting greater blood flow to the muscles themselves.

As can be seen from the preceding description, the cardiovascular system is a complex interplay of many things going on inside the body. Overall, the body adjusts the heart rate to achieve a cardiac output that will deliver adequate blood, oxygen, and nutrients to the muscles during exercise. Heart rate is also affected by the nervous system, as can be seen at the start line of a bicycle race when your heart rate is at 150 beats per minute before the starting gun even goes off! Or you could be tired and pushing yourself harder than ever, yet your heart rate reaches only 160 beats per minute as compared with your normal 175 beats per minute at threshold. In both cases, your nervous system is sending signals to your heart that override your body's physiological demands for cardiac output.

Therefore, although heart rate is an indication of effort, it is an indirect one at best. Similar to a tachometer on a car that tells you how fast the pistons are pumping rather than how many horsepower the engine is producing, heart rate does not tell you the speed or power that you are generating on the bike, but only how fast the heart is pumping. Hunter likes to say that “heart rate tells me the ‘intensity of an athlete's intention,' and that can help me to better understand the athlete in workouts and races.” Also, heart rate can be influenced by many factors related and not related to exercise, such as sleep, caffeine intake, and hydration status. That being said, monitoring your heart rate is beneficial, and you can track fitness changes over time by comparing heart rate with the data channels.

Standing Versus Seated Pedaling

The first and most obvious weight-bearing exercise is running. A lot of energy is required not only to propel yourself forward but also to keep yourself upright and stable. Added to that is the impact force from landing on your feet with each stride. The combination of the two makes for a much higher heart rate, a greater metabolic rate, and more overall stress when running compared with cycling. Cycling is mostly a non-weight-bearing activity, and the bicycle is a highly efficient machine because it removes the impact forces and cradles your body in a position that greatly minimizes the need to support your body weight. But at times you have to stand when riding, and then you have to support a good deal of your body weight (figure 8.8). Whether it's on the flats, in the hills, or in a sprint, you are no longer supporting your weight on the saddle, and you have to rely on your muscles more to keep yourself upright.

Of course, standing typically requires more energy and makes you less economical, but it also leverages more of your body weight over the pedals and recruits additional muscles, thus making higher power output possible. For this reason, we're generally taught to keep the standing to a minimum and to stand only when we need extra power, such as when initiating an acceleration (e.g., sprint, breakaway) or when we need extra power while climbing. Wind resistance is also higher while standing because of the larger surface area exposed.

Millet et al. (2002) tested fit elite and pro cyclists riding for 6 minutes at 75 percent of V?O2max in a velodrome and while seated or standing on a 5.3 percent gradient hill. The cyclists also performed 30-second all-out sprints in the lab and while seated and standing on a gradual hill. Thanks to the improvements in technology, the researchers could take this study out into real terrain and use the subjects' own SRM-equipped bikes with portable gas analyzers, increasing the applicability of the study. As expected, heart rate was about eight beats per minute higher when standing compared with seated uphill. Ventilation was also higher, although no differences were seen in oxygen consumption. Cadence was similar at just under 60 revolutions per minute in both conditions. Most important, no differences were found in either gross efficiency (about 22.5 percent) or economy (4.7 kilojoules of power per liter of oxygen). In the 30-second tests, maximum and mean power were much higher in the standing position compared with the seated position (mean power of about 820 and 650 watts, respectively), despite similar cadences and blood lactate values.

Overall, the ability to produce higher power when sprinting and standing is obvious and intuitive, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, especially the finding that no differences occur in efficiency or economy whether standing or seated. This result means that, although standing creates more stress on the aerobic and cardiovascular system, it does not necessarily cause a decrease in efficiency itself. So standing is not going to cost more energy to perform when you factor in the greater power that you are generating. One obvious caveat is that extended standing while climbing must be practiced to optimize economy. Another caveat is that all the subjects in the study were young, lean, and light, averaging 67 kilograms. For bigger riders with more weight to support, the efficiency and economy equations might be tilted in favor of sitting.

Because overtraining affects the physical responses to training and adaptation, the body must also contend with a wide array of psychosocial stressors, from sports-related (team dynamics, coaches) and environmental (frequent travel, altitude) challenges to personal (relationship, work, financial) issues. Given the multitude of potential contributing factors beyond the quantification of training load, isolating the direct cause of overtraining can be difficult. The primary determinant is likely different for each cyclist. For example, a masters cyclist who juggles training time with a demanding job and a young family may overtrain from an inability to manage these multiple responsibilities. Alternately, a keen junior cyclist just starting in the sport may overtrain from trying to ride too much too soon or may develop overuse injuries from riding overlarge gears. Therefore, the social context of the cyclist must be carefully considered in managing overtraining. In addition, underlying medical issues may predispose (e.g., history of depression) or directly contribute (e.g., injury) to the onset of OTS.

Stages of Overtraining

The principle of overload is fundamental to the process of improving fitness (McNicol et al. 2009). A period of stress followed by recovery results in a “supercompensation” in which the body adapts to the imposed stress and becomes stronger, thus improving performance. The human body is highly adaptable to the stresses imposed on it as long as the stress is not excessive.

The European College of Sport Science, in its 2006 position stand (Meeusen et al. 2006), presented overtraining as a continuum from the desired “normal” and functional overload and functional overreaching (FOR), through to nonfunctional overreaching (NFOR), and ultimately to overtraining syndrome (OTS) and burnout. Although this representation is possibly an oversimplification—debate continues about whether the process of overtraining is a continuum or a series of distinct and independent phases—having standardized definitions as a basis of discussion is helpful.

• Training. A process of overload that is used to disturb the body's normal state of fitness, which results in acute fatigue (one to two days at most), adaptation by the body, and ultimately an improvement in performance. This level of training is what we do most of the time, such as a few hard interval sessions followed by a day or two of easier rides over the course of a week, or two to three weeks of progressive overload followed by a recovery week of reduced training to permit the body to adapt to the stress.
• Overtraining. Within this paradigm, overtraining is used to describe a period in which greater than normal training stress is imposed. An example may be suddenly spending two weeks doing more and harder intervals than you have been used to doing or spending a week at an intense climbing camp in the mountains, where you put in long hours and do lots of hard climbing. As explained in the three definitions that follow, overtraining can be a normal and positive process of overload and supercompensation (see functional overreaching), or it can become a negative stimulus that is more than the cyclist can handle (see nonfunctional overreaching and overtraining syndrome).
• Functional overreaching (FOR). A process in which overtraining, possibly followed by a temporary drop-off in performance lasting days to at most several weeks, results in the body adapting by becoming stronger and thus being able to produce performances that exceed the previous baseline. A critical component of FOR is a period of adequate recovery following the period of overtraining. An example may be a cyclist who spends a week at a climbing camp in the mountains, recovers at home with an easy week, and then settles back into a more normal training program during which he sees his overall riding level improve.
• Nonfunctional overreaching (NFOR). An extreme level of overtraining, often associated with inadequate recovery, in which the drop-off in performance after a period of overload is prolonged and performance stagnates or remains at baseline or lower for weeks or even months. Besides causing physiological changes, this state is often accompanied by psychological disturbances such as irritability, increased fatigue, and decreased vigor. Hormonal disturbances also are more likely within this phase. For example, NFOR might occur if the cyclist returned from a week at the climbing camp and then, without taking a recovery period, continued to push his body by doing a few additional weeks of hard training, thinking that by doing so he could take advantage of his newfound fitness and motivation to reap even greater benefits. With sufficient rest, cyclists in NFOR typically recover over a period of several months.
• Overtraining syndrome (OTS). An extreme level of overtraining, in which performance becomes impaired for many months to years. A host of psychological and physiological impairments can be present, and cyclists who reach this level often burn out completely and quit the sport. In general, rarely does physical stress alone bring about a state of OTS. Rather, the use of the term syndrome is intentional in recognition of the numerous factors that may contribute to its onset. For example, to achieve a state of OTS, the cyclist from the NFOR example described in the previous paragraph would likely have had one or more prior instances of NFOR in addition to a period of increased stress in his home, work, or team life or a physical issue such as an overuse injury or weakened immune system. Think of OTS as the perfect storm of overtraining that you never want to come near!

Although power monitors make direct quantification of training load possible, no hard and fast equation can state that a certain amount of work defines normal training, FOR, NFOR, or OTS. First, all cyclists differ in their ability to respond to a particular workload. Two cyclists riding an identical workout will respond differently based on their number of years in the sport, their particular phase of periodized training, and even their training for the previous day or week. Just as it is pointless to expect your body composition, weight, and resting heart rate to match someone else's, it is equally senseless to expect your potential for overtraining to be similar to another's. Therefore, an individual approach must be applied to training and addressing the possibility of OTS. Even when looking at a single cyclist, predicting the effect of a particular workload can be difficult because the nature of a periodized training plan generally means a wide fluctuation in workload throughout the year, making it hard to establish a baseline for workload or performance.

Heart Rate Monitors

With improved fitness, the defining change in your body is that your cardiac output, or the volume of blood pumped by your heart each minute, increases. Cardiac output is simply heart rate multiplied by stroke volume; the latter is the volume of blood pumped with each heart beat. In an untrained individual, the maximal cardiac output can reach approximately 25 liters per minute, but an elite aerobic athlete may have a value of 35 liters or higher. Obviously, as more blood is pumped, more oxygen is delivered to the muscles, increasing your aerobic energy production. Physiologically, what are some of the major adaptations in your cardiovascular system to enable this?

• Your maximal heart rate will not change with fitness. This value is largely determined by genetics and age.
• Overall blood volume will increase slightly, and some correlation is found between higher aerobic fitness and higher blood volume (Sawka et al. 1992). This result occurs mostly because of increased plasma volume rather than more red blood cells, such that hematocrit (the fraction of solid to liquid in blood) usually decreases with fitness.
• The heart, like your leg muscles, becomes stronger and able to pump blood with greater force. This increase in contractility helps to increase the stroke volume, or the amount of blood pumped with each heart beat.
• Stroke volume also increases by improvements in your body's ability to return blood from the body to the heart, resulting in greater filling of the heart each time.
• The capillary network in your muscles increases in density, permitting greater blood flow to the muscles themselves.

As can be seen from the preceding description, the cardiovascular system is a complex interplay of many things going on inside the body. Overall, the body adjusts the heart rate to achieve a cardiac output that will deliver adequate blood, oxygen, and nutrients to the muscles during exercise. Heart rate is also affected by the nervous system, as can be seen at the start line of a bicycle race when your heart rate is at 150 beats per minute before the starting gun even goes off! Or you could be tired and pushing yourself harder than ever, yet your heart rate reaches only 160 beats per minute as compared with your normal 175 beats per minute at threshold. In both cases, your nervous system is sending signals to your heart that override your body's physiological demands for cardiac output.

Therefore, although heart rate is an indication of effort, it is an indirect one at best. Similar to a tachometer on a car that tells you how fast the pistons are pumping rather than how many horsepower the engine is producing, heart rate does not tell you the speed or power that you are generating on the bike, but only how fast the heart is pumping. Hunter likes to say that “heart rate tells me the ‘intensity of an athlete's intention,' and that can help me to better understand the athlete in workouts and races.” Also, heart rate can be influenced by many factors related and not related to exercise, such as sleep, caffeine intake, and hydration status. That being said, monitoring your heart rate is beneficial, and you can track fitness changes over time by comparing heart rate with the data channels.

Standing Versus Seated Pedaling

The first and most obvious weight-bearing exercise is running. A lot of energy is required not only to propel yourself forward but also to keep yourself upright and stable. Added to that is the impact force from landing on your feet with each stride. The combination of the two makes for a much higher heart rate, a greater metabolic rate, and more overall stress when running compared with cycling. Cycling is mostly a non-weight-bearing activity, and the bicycle is a highly efficient machine because it removes the impact forces and cradles your body in a position that greatly minimizes the need to support your body weight. But at times you have to stand when riding, and then you have to support a good deal of your body weight (figure 8.8). Whether it's on the flats, in the hills, or in a sprint, you are no longer supporting your weight on the saddle, and you have to rely on your muscles more to keep yourself upright.

Of course, standing typically requires more energy and makes you less economical, but it also leverages more of your body weight over the pedals and recruits additional muscles, thus making higher power output possible. For this reason, we're generally taught to keep the standing to a minimum and to stand only when we need extra power, such as when initiating an acceleration (e.g., sprint, breakaway) or when we need extra power while climbing. Wind resistance is also higher while standing because of the larger surface area exposed.

Millet et al. (2002) tested fit elite and pro cyclists riding for 6 minutes at 75 percent of V?O2max in a velodrome and while seated or standing on a 5.3 percent gradient hill. The cyclists also performed 30-second all-out sprints in the lab and while seated and standing on a gradual hill. Thanks to the improvements in technology, the researchers could take this study out into real terrain and use the subjects' own SRM-equipped bikes with portable gas analyzers, increasing the applicability of the study. As expected, heart rate was about eight beats per minute higher when standing compared with seated uphill. Ventilation was also higher, although no differences were seen in oxygen consumption. Cadence was similar at just under 60 revolutions per minute in both conditions. Most important, no differences were found in either gross efficiency (about 22.5 percent) or economy (4.7 kilojoules of power per liter of oxygen). In the 30-second tests, maximum and mean power were much higher in the standing position compared with the seated position (mean power of about 820 and 650 watts, respectively), despite similar cadences and blood lactate values.

Overall, the ability to produce higher power when sprinting and standing is obvious and intuitive, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, especially the finding that no differences occur in efficiency or economy whether standing or seated. This result means that, although standing creates more stress on the aerobic and cardiovascular system, it does not necessarily cause a decrease in efficiency itself. So standing is not going to cost more energy to perform when you factor in the greater power that you are generating. One obvious caveat is that extended standing while climbing must be practiced to optimize economy. Another caveat is that all the subjects in the study were young, lean, and light, averaging 67 kilograms. For bigger riders with more weight to support, the efficiency and economy equations might be tilted in favor of sitting.

Because overtraining affects the physical responses to training and adaptation, the body must also contend with a wide array of psychosocial stressors, from sports-related (team dynamics, coaches) and environmental (frequent travel, altitude) challenges to personal (relationship, work, financial) issues. Given the multitude of potential contributing factors beyond the quantification of training load, isolating the direct cause of overtraining can be difficult. The primary determinant is likely different for each cyclist. For example, a masters cyclist who juggles training time with a demanding job and a young family may overtrain from an inability to manage these multiple responsibilities. Alternately, a keen junior cyclist just starting in the sport may overtrain from trying to ride too much too soon or may develop overuse injuries from riding overlarge gears. Therefore, the social context of the cyclist must be carefully considered in managing overtraining. In addition, underlying medical issues may predispose (e.g., history of depression) or directly contribute (e.g., injury) to the onset of OTS.

Stages of Overtraining

The principle of overload is fundamental to the process of improving fitness (McNicol et al. 2009). A period of stress followed by recovery results in a “supercompensation” in which the body adapts to the imposed stress and becomes stronger, thus improving performance. The human body is highly adaptable to the stresses imposed on it as long as the stress is not excessive.

The European College of Sport Science, in its 2006 position stand (Meeusen et al. 2006), presented overtraining as a continuum from the desired “normal” and functional overload and functional overreaching (FOR), through to nonfunctional overreaching (NFOR), and ultimately to overtraining syndrome (OTS) and burnout. Although this representation is possibly an oversimplification—debate continues about whether the process of overtraining is a continuum or a series of distinct and independent phases—having standardized definitions as a basis of discussion is helpful.

• Training. A process of overload that is used to disturb the body's normal state of fitness, which results in acute fatigue (one to two days at most), adaptation by the body, and ultimately an improvement in performance. This level of training is what we do most of the time, such as a few hard interval sessions followed by a day or two of easier rides over the course of a week, or two to three weeks of progressive overload followed by a recovery week of reduced training to permit the body to adapt to the stress.
• Overtraining. Within this paradigm, overtraining is used to describe a period in which greater than normal training stress is imposed. An example may be suddenly spending two weeks doing more and harder intervals than you have been used to doing or spending a week at an intense climbing camp in the mountains, where you put in long hours and do lots of hard climbing. As explained in the three definitions that follow, overtraining can be a normal and positive process of overload and supercompensation (see functional overreaching), or it can become a negative stimulus that is more than the cyclist can handle (see nonfunctional overreaching and overtraining syndrome).
• Functional overreaching (FOR). A process in which overtraining, possibly followed by a temporary drop-off in performance lasting days to at most several weeks, results in the body adapting by becoming stronger and thus being able to produce performances that exceed the previous baseline. A critical component of FOR is a period of adequate recovery following the period of overtraining. An example may be a cyclist who spends a week at a climbing camp in the mountains, recovers at home with an easy week, and then settles back into a more normal training program during which he sees his overall riding level improve.
• Nonfunctional overreaching (NFOR). An extreme level of overtraining, often associated with inadequate recovery, in which the drop-off in performance after a period of overload is prolonged and performance stagnates or remains at baseline or lower for weeks or even months. Besides causing physiological changes, this state is often accompanied by psychological disturbances such as irritability, increased fatigue, and decreased vigor. Hormonal disturbances also are more likely within this phase. For example, NFOR might occur if the cyclist returned from a week at the climbing camp and then, without taking a recovery period, continued to push his body by doing a few additional weeks of hard training, thinking that by doing so he could take advantage of his newfound fitness and motivation to reap even greater benefits. With sufficient rest, cyclists in NFOR typically recover over a period of several months.
• Overtraining syndrome (OTS). An extreme level of overtraining, in which performance becomes impaired for many months to years. A host of psychological and physiological impairments can be present, and cyclists who reach this level often burn out completely and quit the sport. In general, rarely does physical stress alone bring about a state of OTS. Rather, the use of the term syndrome is intentional in recognition of the numerous factors that may contribute to its onset. For example, to achieve a state of OTS, the cyclist from the NFOR example described in the previous paragraph would likely have had one or more prior instances of NFOR in addition to a period of increased stress in his home, work, or team life or a physical issue such as an overuse injury or weakened immune system. Think of OTS as the perfect storm of overtraining that you never want to come near!

Although power monitors make direct quantification of training load possible, no hard and fast equation can state that a certain amount of work defines normal training, FOR, NFOR, or OTS. First, all cyclists differ in their ability to respond to a particular workload. Two cyclists riding an identical workout will respond differently based on their number of years in the sport, their particular phase of periodized training, and even their training for the previous day or week. Just as it is pointless to expect your body composition, weight, and resting heart rate to match someone else's, it is equally senseless to expect your potential for overtraining to be similar to another's. Therefore, an individual approach must be applied to training and addressing the possibility of OTS. Even when looking at a single cyclist, predicting the effect of a particular workload can be difficult because the nature of a periodized training plan generally means a wide fluctuation in workload throughout the year, making it hard to establish a baseline for workload or performance.

Heart Rate Monitors

With improved fitness, the defining change in your body is that your cardiac output, or the volume of blood pumped by your heart each minute, increases. Cardiac output is simply heart rate multiplied by stroke volume; the latter is the volume of blood pumped with each heart beat. In an untrained individual, the maximal cardiac output can reach approximately 25 liters per minute, but an elite aerobic athlete may have a value of 35 liters or higher. Obviously, as more blood is pumped, more oxygen is delivered to the muscles, increasing your aerobic energy production. Physiologically, what are some of the major adaptations in your cardiovascular system to enable this?

• Your maximal heart rate will not change with fitness. This value is largely determined by genetics and age.
• Overall blood volume will increase slightly, and some correlation is found between higher aerobic fitness and higher blood volume (Sawka et al. 1992). This result occurs mostly because of increased plasma volume rather than more red blood cells, such that hematocrit (the fraction of solid to liquid in blood) usually decreases with fitness.
• The heart, like your leg muscles, becomes stronger and able to pump blood with greater force. This increase in contractility helps to increase the stroke volume, or the amount of blood pumped with each heart beat.
• Stroke volume also increases by improvements in your body's ability to return blood from the body to the heart, resulting in greater filling of the heart each time.
• The capillary network in your muscles increases in density, permitting greater blood flow to the muscles themselves.

As can be seen from the preceding description, the cardiovascular system is a complex interplay of many things going on inside the body. Overall, the body adjusts the heart rate to achieve a cardiac output that will deliver adequate blood, oxygen, and nutrients to the muscles during exercise. Heart rate is also affected by the nervous system, as can be seen at the start line of a bicycle race when your heart rate is at 150 beats per minute before the starting gun even goes off! Or you could be tired and pushing yourself harder than ever, yet your heart rate reaches only 160 beats per minute as compared with your normal 175 beats per minute at threshold. In both cases, your nervous system is sending signals to your heart that override your body's physiological demands for cardiac output.

Therefore, although heart rate is an indication of effort, it is an indirect one at best. Similar to a tachometer on a car that tells you how fast the pistons are pumping rather than how many horsepower the engine is producing, heart rate does not tell you the speed or power that you are generating on the bike, but only how fast the heart is pumping. Hunter likes to say that “heart rate tells me the ‘intensity of an athlete's intention,' and that can help me to better understand the athlete in workouts and races.” Also, heart rate can be influenced by many factors related and not related to exercise, such as sleep, caffeine intake, and hydration status. That being said, monitoring your heart rate is beneficial, and you can track fitness changes over time by comparing heart rate with the data channels.

Standing Versus Seated Pedaling

The first and most obvious weight-bearing exercise is running. A lot of energy is required not only to propel yourself forward but also to keep yourself upright and stable. Added to that is the impact force from landing on your feet with each stride. The combination of the two makes for a much higher heart rate, a greater metabolic rate, and more overall stress when running compared with cycling. Cycling is mostly a non-weight-bearing activity, and the bicycle is a highly efficient machine because it removes the impact forces and cradles your body in a position that greatly minimizes the need to support your body weight. But at times you have to stand when riding, and then you have to support a good deal of your body weight (figure 8.8). Whether it's on the flats, in the hills, or in a sprint, you are no longer supporting your weight on the saddle, and you have to rely on your muscles more to keep yourself upright.

Of course, standing typically requires more energy and makes you less economical, but it also leverages more of your body weight over the pedals and recruits additional muscles, thus making higher power output possible. For this reason, we're generally taught to keep the standing to a minimum and to stand only when we need extra power, such as when initiating an acceleration (e.g., sprint, breakaway) or when we need extra power while climbing. Wind resistance is also higher while standing because of the larger surface area exposed.

Millet et al. (2002) tested fit elite and pro cyclists riding for 6 minutes at 75 percent of V?O2max in a velodrome and while seated or standing on a 5.3 percent gradient hill. The cyclists also performed 30-second all-out sprints in the lab and while seated and standing on a gradual hill. Thanks to the improvements in technology, the researchers could take this study out into real terrain and use the subjects' own SRM-equipped bikes with portable gas analyzers, increasing the applicability of the study. As expected, heart rate was about eight beats per minute higher when standing compared with seated uphill. Ventilation was also higher, although no differences were seen in oxygen consumption. Cadence was similar at just under 60 revolutions per minute in both conditions. Most important, no differences were found in either gross efficiency (about 22.5 percent) or economy (4.7 kilojoules of power per liter of oxygen). In the 30-second tests, maximum and mean power were much higher in the standing position compared with the seated position (mean power of about 820 and 650 watts, respectively), despite similar cadences and blood lactate values.

Overall, the ability to produce higher power when sprinting and standing is obvious and intuitive, as are the higher heart rates when climbing and standing. The main novelty of the study comes in the analysis of efficiency, especially the finding that no differences occur in efficiency or economy whether standing or seated. This result means that, although standing creates more stress on the aerobic and cardiovascular system, it does not necessarily cause a decrease in efficiency itself. So standing is not going to cost more energy to perform when you factor in the greater power that you are generating. One obvious caveat is that extended standing while climbing must be practiced to optimize economy. Another caveat is that all the subjects in the study were young, lean, and light, averaging 67 kilograms. For bigger riders with more weight to support, the efficiency and economy equations might be tilted in favor of sitting.