The completely revised seventh edition of Fitness & Health offers a comprehensive understanding of the exercise–health relationship and provides a framework for attaining health and fitness goals. This one-stop handbook for students and fitness professionals explores the physiology and benefits of fitness while also providing information and tools for improving health and wellness. Authors Brian J. Sharkey and Steven E. Gaskill have 60 years of combined experience in the field, as evidenced in the depth of content and accessible style of writing. The book aims not only to educate but also to inspire the audience to put the suggested methods into practice and have a positive effect on their quality of life.
Fitness & Health, Seventh Edition, includes fresh, new content and has been restructured to enhance the educational experience:
• An entirely new chapter detailing behavior change, helping readers better understand the psychology of activity and how to modify individual behaviors using documented strategies
• A revised chapter on the physiology of fitness to help readers grasp the science behind aerobic and muscular fitness
• Proven methods for achieving aerobic and muscular fitness, plus strategies for exercising in high heat and humidity, extreme cold, high altitude, and environments with low air quality
• New information on physical activity and brain health that shows how an active life improves learning, higher-order brain processes, and academic achievement
• A detailed explanation of the Exercise is Medicine movement that highlights the benefits of regular physical activity in terms of improving quality of life and reducing health risks
Students will excel with chapter summaries of content for easier review and tables and figures that organize information for quick reference. The seventh edition also includes special elements to highlight interesting content on health and fitness, including important health behaviors, testing procedures, and proven fitness programs. In addition, instructors benefit from the inclusion of new ancillaries containing an instructor guide complete with lab activities, a test package, and a presentation package plus image bank.
With Fitness & Health, students learn the body’s response to exercise and acquire strategies for motivating themselves or others to commit to an active and healthy life. The book explains how the body responds to physical activity; why physical activity is beneficial to health; and how physical activity can help people increase aerobic and muscular fitness, achieve and maintain a healthy weight, enhance performance in work and sport, and improve vitality.
Part I. Physical Activity, Fitness, and Health
Chapter 1. Health Benefits of Activity and Fitness
Activity Reduces the Risk of Coronary Artery Disease
Activity Reduces the Risk of Chronic Diseases
Activity Increases Longevity
Summary
Chapter 2. Mental and Cognitive Health: A Sound Mind in a Sound Body
Activity Reduces Anxiety and Depression
Activity Minimizes Stress
Activity Improves Cognitive Health
Activity as a Positive Addiction
Summary
Chapter 3. Activity and Personal Health Assessment: It’s Your Responsibility
Functions of Health Screening and Early Detection
Annual Medical Examination
Cholesterol Screening
Pre-Exercise Medical Examination
Evaluating the Risks of Activity
Individual Health Risk Analysis
Summary
Part II. Turning Your Life Around
Chapter 4. Psychology of Activity: Learning to Play
Motivation
Adherence
Goal Setting
Setting Your Preference to Exertion
Summary
Chapter 5. Behavior Change: Gaining Control
Activity in Modern Society
Barriers to Physical Activity
Environment and Behavior
Stages of Behavioral Change
Behavior Modification Strategies
Positive Behavior Maintenance
Relapse Solutions
Visualization Strategies
Summary
Chapter 6. Meaningful Activity: Lifetime Vitality
Meaningful Physical Activity
Incorporating Purposeful Activity into Daily Living
Environment and Purposeful Activity
Aging and Activity
Health Habits for Longevity
Personality Attributes for Longevity
Age and Performance
Summary
Part III. Understanding Fitness
Chapter 7. Physiology of Fitness: Muscles, Energy, and Oxygen
Muscle Contractions
Energy Sources
Energy for Contractions
Supply and Support Systems
Genetic Responses to Exercise
Summary
Chapter 8. Aerobic Fitness: Stamina and Efficiency
Aerobic Exercise
Aerobic Fitness
Aerobic Training Effects
Aerobic Training and Muscle Function
Aerobic Training and Body Composition
Aerobic Training and the Skeletal System
Training Supply and Support
Specificity of Training
Aerobic Fitness Field Tests
Summary
Chapter 9. Muscular Fitness: Strength and Endurance
Muscular Strength
Muscular Endurance
Flexibility
Speed
Power
Agility and Skill
Balance
Benefits of Muscular Fitness
Strength Training Effects
Endurance Training Effects
Methods of Training
Muscle Soreness
Force–Velocity Relationship
Preload and Elastic Recoil
Core Training
Muscular Fitness Field Tests
Summary
Part IV. Improving Fitness
Chapter 10. Aerobic Fitness Training: Steps for Success
Fitness Prescription
Training Tips
Aerobic Fitness Options
Exercise Risks
Sample Aerobic Fitness Prescriptions
Summary
Chapter 11. Muscular Fitness Training: Lifetime Mobility
Muscular Strength Fitness Prescription
Muscular Endurance Fitness Prescription
Sample Muscular Fitness Prescriptions
Summary
Part V. Activity and Weight Control
Chapter 12. Energy and Nutrition: Fuel for the Active Life
Nutrients
Dietary Guidelines
Energy Intake
Energy Expenditure
Calculating Caloric Intake
Estimating Caloric Expenditure
Diet and Performance
Summary
Chapter 13. Weight Control: More Than Calories Count
Overweight and Obesity
Measuring Body Fat
Ideal Body Weight
Activity and Weight Control
Exercise Prescription for Weight Control
Adopting a Healthy Diet
Weight-Control Fallacies
Sensible Weight Gain
Summary
Part VI. Performance
Chapter 14. Training: Athletic Performance
Training Principles
Training Fallacies
Designing Your Training Program
Periodizing Your Training Program
Psychology of Performance
Overtraining
Cross-Training
Fitness and Work
Summary
Chapter 15. Environment: Acclimate, Then Perform
Regulating Temperature
Exercising in the Heat
Exercising in the Cold
Exercising at Altitude
Avoiding the Effects of Air Pollution
Summary
Brian J. Sharkey, PhD, has nearly 40 years of experience as a leading fitness researcher, educator, and author. Sharkey served as director of the University of Montana’s Human Performance Laboratory for many years and remains associated with the university and lab as professor emeritus. He also served as a consultant with the U.S. Forest Service in the areas of fitness, health, and work capacity.
Sharkey is a fellow and past president of the American College of Sports Medicine and has served on the board of trustees. He served on the NCAA committee on competitive safeguards and medical aspects of sports, where he chaired the Sports Science and Safety subcommittee, which uses research and data on injury to improve the safety of intercollegiate athletes. Sharkey also coordinated the U.S. Ski Team Nordic Sportsmedicine Council. In 2009, Sharkey recevied the Fire Safety Award from the International Association of Wildland Firefighters.
Sharkey and his wife, Anne, reside in Missoula, Montana. He enjoys hiking, paddling, cycling, and both cross-country and downhill skiing.
Steven E. Gaskill, PhD, is a professor in the department of health and human performance at the University of Montana. His research interests include the relationship of physical activity to cognitive functioning in children; submaximal aerobic fitness and its relationship to work capacity and chronic disease; and long-duration work and exercise fitness as related to fitness, fatigue, immune function, and cognitive performance. Gaskill has published over 40 articles in refereed journals, presented his reasearch at numerous conferences, and authored three books.
Gaskill worked for the U.S. ski team for 10 years as head coach of the Nordic combined (ski jumping and cross-country skiing) and cross-country teams and as director of the coaches’ educational programs. He has coached at three Olympic Games, and 20 skiers who have trained under him have competed in the Olympics. In 1992, the U.S. Ski Association named him the U.S. Cross-Country Coach of the Year.
Gaskill enjoys backpacking, tennis, mountain biking, cross-country skiing, fishing, and mountaineering. Serious about the active life, he continues to be active year round with his wife, Kathy
Sharkey and Gaskill also coauthored Sport Physiology for Coaches (Human Kinetics, 2006).
Activity improves cognitive health
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function?
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function? In his book Spark: The Revolutionary New Science of Exercise and the Brain, John Ratey summarizes the positive affect that physical activity has on brain function (Ratey and Hagerman 2008). Current research has even demonstrated that physical activity can stimulate neurogenesis (the growth of new brain cells) while also increasing the number of neural connections (Bekinschtein et al. 2011). A growing body of knowledge shows that youth and adolescents who participate in regular moderate and vigorous physical activity do better at school in terms of academic achievement, attendance, attention, memorization, and integration. They also exhibit fewer disciplinary problems and incidences of attention-deficit/hyperactivity disorder (ADHD) (Gaskill, Miller, and Wambold 2012, Trudeau and Shephard 2008).
These studies make a strong case for increasing physical activity in schools rather than the current trend to reduce recess, cut physical education, and spend more time sitting in the classroom. The understanding that physical activity was related to brain health is not new. Ancient philosophers believed that bodily activity improved brain fitness.Plato, Hippocrates, and many others stressed the mind-body connection throughout their writings, yet it is only recently that both empirical evidence and mechanistic studies are beginning to document the basis for the body-mind connection. Let's take a look at some of the opinions and evidence.
In a study of 482 2nd- through 12th-grade students, we (Gaskill, Miller, and Wambold 2012) evaluated physical activity compared to both grade point average and standardized tests scores. The most active fourth of the students averaged nearly a full grade point higher and did significantly better on standardized tests than the quartile of least active students. The academic achievement gap increased with grade level. By high school, the GPA gap was nearly 1.5 grade points (3.52 for the most active versus 2.14 for the least active). Students in the Naperville, Illinois school district are all required to participate in nearly an hour of daily physical activity, which substantially raises their heart rates. They also placed 1st in the world in science testing and 6th in math. Additionally, their rates of overweight and obesity are less than 10 percent, nearly half of the rate of nearby communities and one-third of the national average (Ratey and Hagerman 2008).
During the last 5 years, more than 100 studies have documented the effect of physical activity or fitness on academic performance (Singh et al. 2012). In a number of studies, up to an hour of physical activity time replaced academic classroom time. In every study, academic performance measures either increased or at least did not decrease, even when time was taken from academic time for physical activity. In addition, attendance improved, and disciplinary referrals and attention deficit were reduced. What is generally not mentioned in these studies are all of the other benefits of physical activity: reduced obesity rates, decreased risk of chronic disease, improved self-efficacy, and all of the other benefits discussed in this book. In animal studies, and using new imaging techniques in humans, scientists have shown that increased physical activity helps our brains to grow new neurons and to increase the connections between neurons (Bekinschtein et al. 2011). This brain growth, termed neurogenesis, was previously believed not to occur in adults. Data suggest that coordinative and sustained aerobic exercise dramatically improve brain function. This is particularly true for youth, but adults and the elderly can also both improve cognition and slow the rates of decline.
The stimulus for neurogenesis and the associated improved memory, integration of information, and attention span that leads to higher cognitive function and academic achievement is the result of a number of hormones and brain chemicals that are increased or decreased by the exercise stimulus. Contracting muscles release growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) and help stimulate blood vessel growth in both the body and the brain. Vascular diameter is enlarged by nitric oxide, increasing blood flow and decreasing hardening of the arteries, even in the brain. Exercise stimulates insulin-like growth factor, thus better regulating insulin while also improving synaptic plasticity in the brain. As blood glucose decreases as a result of exercise, both exercise and lower blood glucose stimulate brain-derived neurotropic factor, which has been termed “Miracle Grow for the brain” by Dr. Ratey (Ratey and Hagerman 2008). Exercise also stimulates a number of neurotransmitters and neurotrophin to stimulate and encourage growth of the hippocampus area of the brain. These effects elevate our mood and reduce our chances for dementia. So, there really is a body-brain connection. Current research shows that an active lifestyle has many positive outcomes in our brains.
In the fall of 2011, the American College of Sports Medicine held the first conference dedicated to how physical activity affects cognition and learning. More than 400 scientists, teachers, administrators, doctors, and politicians attended. The exciting news is that many schools and communities are adapting new policies that encourage or require physical activity on a regular basis for school youth. Those schools are seeing improvements in learning, behavior, attendance, and graduation, as well as decreases in attention-deficit/hyperactivity disorder (ADHD). The following box lists best practices learned at this conference, along with some great resources that parents and school officials can use in order to change their schools.
http://www.humankinetics.com/AcuCustom/Sitename/DAM/091/SEp_Main._45.png
How built and economic environments effect health behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades.
Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5-11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18-32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?
Physical activity is the positive approach to weight control
Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action.
Weight control is a lifelong journey. The best time to start is when you are young; the next best time is today. Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action. No other approach is so physiologically sound, so definite, so enjoyable. Action is more psychologically rewarding than avoidance. When you take a walk after dinner, you relax, improve your digestion, enhance your vitality, and burn fat and calories. After the walk, you feel better both physically and emotionally. Problems loom large when you sit and brood, but how quickly they shrink when you undertake a plan of action!
Dieting carries negative connotations of avoidance, deprivation, and punishment. It creates false hopes, contributes to stress, ruins the disposition, causes fatigue, and often leads to increases in body weight and fat. The ups and downs of frequent dieting (weight cycling, or yo-yo dieting) increase the risk of psychopathology, dissatisfaction with life, binge eating, morbidity, and mortality (Brownell and Rodin 1994). This is also true in young women who are dieting for body image, with the additional problem that weight cycling may promote the onset of atherosclerosis (Montani et al. 2006).
The most exciting part of this chapter deals with the extra benefits that you obtain with improved fitness, benefits that exceed the effects of activity. This material, although not new, is finally coming to the attention of public health and fitness professionals. In our estimation, these extra benefits provide the most convincing case for activity and fitness and their relationship to weight control and health.
Finally, we outline activity, food choices (diet), and a lifelong approach to rational weight control.
Some types of exercise are better than others for weight control. As you know, we gradually shift from fat to carbohydrate metabolism as exercise becomes more vigorous. If you want to burn excess fat, consider light to moderate exercise (see table 13.2). Because you cannot sustain extremely vigorous activity for long, total caloric expenditure may not be great. In addition, fat utilization increases over time, with more fat being burned after 30 minutes of exercise. You can continue light to moderate activity for hours without undue fatigue, thereby allowing significant fat metabolism and caloric expenditure.
Incidentally, while we are on the subject of fat metabolism, the best time to exercise for weight control may be in the morning, before breakfast, when you are more likely to burn fat after an overnight fast. So, if you are interested in fat metabolism and weight control, try morning exercise. If that approach doesn't suit your biological clock, don't despair. Exercise always burns calories, so it always contributes to weight control.
Perhaps the best idea is to find an active hobby or sport and make it an essential part of your life. Try woodworking, racquetball, golf, or dancing. Get a canoe or cross-country skis, or start a garden. Dig out the tennis racket and try it. Go ice-skating in winter or roller-skating any time of year. You'll enrich your life and lower your weight at the same time. Of course, you'll look better too!
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/tb13_Main.2.png
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/SEp_Main._331.png
Activity improves cognitive health
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function?
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function? In his book Spark: The Revolutionary New Science of Exercise and the Brain, John Ratey summarizes the positive affect that physical activity has on brain function (Ratey and Hagerman 2008). Current research has even demonstrated that physical activity can stimulate neurogenesis (the growth of new brain cells) while also increasing the number of neural connections (Bekinschtein et al. 2011). A growing body of knowledge shows that youth and adolescents who participate in regular moderate and vigorous physical activity do better at school in terms of academic achievement, attendance, attention, memorization, and integration. They also exhibit fewer disciplinary problems and incidences of attention-deficit/hyperactivity disorder (ADHD) (Gaskill, Miller, and Wambold 2012, Trudeau and Shephard 2008).
These studies make a strong case for increasing physical activity in schools rather than the current trend to reduce recess, cut physical education, and spend more time sitting in the classroom. The understanding that physical activity was related to brain health is not new. Ancient philosophers believed that bodily activity improved brain fitness.Plato, Hippocrates, and many others stressed the mind-body connection throughout their writings, yet it is only recently that both empirical evidence and mechanistic studies are beginning to document the basis for the body-mind connection. Let's take a look at some of the opinions and evidence.
In a study of 482 2nd- through 12th-grade students, we (Gaskill, Miller, and Wambold 2012) evaluated physical activity compared to both grade point average and standardized tests scores. The most active fourth of the students averaged nearly a full grade point higher and did significantly better on standardized tests than the quartile of least active students. The academic achievement gap increased with grade level. By high school, the GPA gap was nearly 1.5 grade points (3.52 for the most active versus 2.14 for the least active). Students in the Naperville, Illinois school district are all required to participate in nearly an hour of daily physical activity, which substantially raises their heart rates. They also placed 1st in the world in science testing and 6th in math. Additionally, their rates of overweight and obesity are less than 10 percent, nearly half of the rate of nearby communities and one-third of the national average (Ratey and Hagerman 2008).
During the last 5 years, more than 100 studies have documented the effect of physical activity or fitness on academic performance (Singh et al. 2012). In a number of studies, up to an hour of physical activity time replaced academic classroom time. In every study, academic performance measures either increased or at least did not decrease, even when time was taken from academic time for physical activity. In addition, attendance improved, and disciplinary referrals and attention deficit were reduced. What is generally not mentioned in these studies are all of the other benefits of physical activity: reduced obesity rates, decreased risk of chronic disease, improved self-efficacy, and all of the other benefits discussed in this book. In animal studies, and using new imaging techniques in humans, scientists have shown that increased physical activity helps our brains to grow new neurons and to increase the connections between neurons (Bekinschtein et al. 2011). This brain growth, termed neurogenesis, was previously believed not to occur in adults. Data suggest that coordinative and sustained aerobic exercise dramatically improve brain function. This is particularly true for youth, but adults and the elderly can also both improve cognition and slow the rates of decline.
The stimulus for neurogenesis and the associated improved memory, integration of information, and attention span that leads to higher cognitive function and academic achievement is the result of a number of hormones and brain chemicals that are increased or decreased by the exercise stimulus. Contracting muscles release growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) and help stimulate blood vessel growth in both the body and the brain. Vascular diameter is enlarged by nitric oxide, increasing blood flow and decreasing hardening of the arteries, even in the brain. Exercise stimulates insulin-like growth factor, thus better regulating insulin while also improving synaptic plasticity in the brain. As blood glucose decreases as a result of exercise, both exercise and lower blood glucose stimulate brain-derived neurotropic factor, which has been termed “Miracle Grow for the brain” by Dr. Ratey (Ratey and Hagerman 2008). Exercise also stimulates a number of neurotransmitters and neurotrophin to stimulate and encourage growth of the hippocampus area of the brain. These effects elevate our mood and reduce our chances for dementia. So, there really is a body-brain connection. Current research shows that an active lifestyle has many positive outcomes in our brains.
In the fall of 2011, the American College of Sports Medicine held the first conference dedicated to how physical activity affects cognition and learning. More than 400 scientists, teachers, administrators, doctors, and politicians attended. The exciting news is that many schools and communities are adapting new policies that encourage or require physical activity on a regular basis for school youth. Those schools are seeing improvements in learning, behavior, attendance, and graduation, as well as decreases in attention-deficit/hyperactivity disorder (ADHD). The following box lists best practices learned at this conference, along with some great resources that parents and school officials can use in order to change their schools.
http://www.humankinetics.com/AcuCustom/Sitename/DAM/091/SEp_Main._45.png
How built and economic environments effect health behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades.
Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5-11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18-32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?
Physical activity is the positive approach to weight control
Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action.
Weight control is a lifelong journey. The best time to start is when you are young; the next best time is today. Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action. No other approach is so physiologically sound, so definite, so enjoyable. Action is more psychologically rewarding than avoidance. When you take a walk after dinner, you relax, improve your digestion, enhance your vitality, and burn fat and calories. After the walk, you feel better both physically and emotionally. Problems loom large when you sit and brood, but how quickly they shrink when you undertake a plan of action!
Dieting carries negative connotations of avoidance, deprivation, and punishment. It creates false hopes, contributes to stress, ruins the disposition, causes fatigue, and often leads to increases in body weight and fat. The ups and downs of frequent dieting (weight cycling, or yo-yo dieting) increase the risk of psychopathology, dissatisfaction with life, binge eating, morbidity, and mortality (Brownell and Rodin 1994). This is also true in young women who are dieting for body image, with the additional problem that weight cycling may promote the onset of atherosclerosis (Montani et al. 2006).
The most exciting part of this chapter deals with the extra benefits that you obtain with improved fitness, benefits that exceed the effects of activity. This material, although not new, is finally coming to the attention of public health and fitness professionals. In our estimation, these extra benefits provide the most convincing case for activity and fitness and their relationship to weight control and health.
Finally, we outline activity, food choices (diet), and a lifelong approach to rational weight control.
Some types of exercise are better than others for weight control. As you know, we gradually shift from fat to carbohydrate metabolism as exercise becomes more vigorous. If you want to burn excess fat, consider light to moderate exercise (see table 13.2). Because you cannot sustain extremely vigorous activity for long, total caloric expenditure may not be great. In addition, fat utilization increases over time, with more fat being burned after 30 minutes of exercise. You can continue light to moderate activity for hours without undue fatigue, thereby allowing significant fat metabolism and caloric expenditure.
Incidentally, while we are on the subject of fat metabolism, the best time to exercise for weight control may be in the morning, before breakfast, when you are more likely to burn fat after an overnight fast. So, if you are interested in fat metabolism and weight control, try morning exercise. If that approach doesn't suit your biological clock, don't despair. Exercise always burns calories, so it always contributes to weight control.
Perhaps the best idea is to find an active hobby or sport and make it an essential part of your life. Try woodworking, racquetball, golf, or dancing. Get a canoe or cross-country skis, or start a garden. Dig out the tennis racket and try it. Go ice-skating in winter or roller-skating any time of year. You'll enrich your life and lower your weight at the same time. Of course, you'll look better too!
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/tb13_Main.2.png
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/SEp_Main._331.png
Activity improves cognitive health
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function?
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function? In his book Spark: The Revolutionary New Science of Exercise and the Brain, John Ratey summarizes the positive affect that physical activity has on brain function (Ratey and Hagerman 2008). Current research has even demonstrated that physical activity can stimulate neurogenesis (the growth of new brain cells) while also increasing the number of neural connections (Bekinschtein et al. 2011). A growing body of knowledge shows that youth and adolescents who participate in regular moderate and vigorous physical activity do better at school in terms of academic achievement, attendance, attention, memorization, and integration. They also exhibit fewer disciplinary problems and incidences of attention-deficit/hyperactivity disorder (ADHD) (Gaskill, Miller, and Wambold 2012, Trudeau and Shephard 2008).
These studies make a strong case for increasing physical activity in schools rather than the current trend to reduce recess, cut physical education, and spend more time sitting in the classroom. The understanding that physical activity was related to brain health is not new. Ancient philosophers believed that bodily activity improved brain fitness.Plato, Hippocrates, and many others stressed the mind-body connection throughout their writings, yet it is only recently that both empirical evidence and mechanistic studies are beginning to document the basis for the body-mind connection. Let's take a look at some of the opinions and evidence.
In a study of 482 2nd- through 12th-grade students, we (Gaskill, Miller, and Wambold 2012) evaluated physical activity compared to both grade point average and standardized tests scores. The most active fourth of the students averaged nearly a full grade point higher and did significantly better on standardized tests than the quartile of least active students. The academic achievement gap increased with grade level. By high school, the GPA gap was nearly 1.5 grade points (3.52 for the most active versus 2.14 for the least active). Students in the Naperville, Illinois school district are all required to participate in nearly an hour of daily physical activity, which substantially raises their heart rates. They also placed 1st in the world in science testing and 6th in math. Additionally, their rates of overweight and obesity are less than 10 percent, nearly half of the rate of nearby communities and one-third of the national average (Ratey and Hagerman 2008).
During the last 5 years, more than 100 studies have documented the effect of physical activity or fitness on academic performance (Singh et al. 2012). In a number of studies, up to an hour of physical activity time replaced academic classroom time. In every study, academic performance measures either increased or at least did not decrease, even when time was taken from academic time for physical activity. In addition, attendance improved, and disciplinary referrals and attention deficit were reduced. What is generally not mentioned in these studies are all of the other benefits of physical activity: reduced obesity rates, decreased risk of chronic disease, improved self-efficacy, and all of the other benefits discussed in this book. In animal studies, and using new imaging techniques in humans, scientists have shown that increased physical activity helps our brains to grow new neurons and to increase the connections between neurons (Bekinschtein et al. 2011). This brain growth, termed neurogenesis, was previously believed not to occur in adults. Data suggest that coordinative and sustained aerobic exercise dramatically improve brain function. This is particularly true for youth, but adults and the elderly can also both improve cognition and slow the rates of decline.
The stimulus for neurogenesis and the associated improved memory, integration of information, and attention span that leads to higher cognitive function and academic achievement is the result of a number of hormones and brain chemicals that are increased or decreased by the exercise stimulus. Contracting muscles release growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) and help stimulate blood vessel growth in both the body and the brain. Vascular diameter is enlarged by nitric oxide, increasing blood flow and decreasing hardening of the arteries, even in the brain. Exercise stimulates insulin-like growth factor, thus better regulating insulin while also improving synaptic plasticity in the brain. As blood glucose decreases as a result of exercise, both exercise and lower blood glucose stimulate brain-derived neurotropic factor, which has been termed “Miracle Grow for the brain” by Dr. Ratey (Ratey and Hagerman 2008). Exercise also stimulates a number of neurotransmitters and neurotrophin to stimulate and encourage growth of the hippocampus area of the brain. These effects elevate our mood and reduce our chances for dementia. So, there really is a body-brain connection. Current research shows that an active lifestyle has many positive outcomes in our brains.
In the fall of 2011, the American College of Sports Medicine held the first conference dedicated to how physical activity affects cognition and learning. More than 400 scientists, teachers, administrators, doctors, and politicians attended. The exciting news is that many schools and communities are adapting new policies that encourage or require physical activity on a regular basis for school youth. Those schools are seeing improvements in learning, behavior, attendance, and graduation, as well as decreases in attention-deficit/hyperactivity disorder (ADHD). The following box lists best practices learned at this conference, along with some great resources that parents and school officials can use in order to change their schools.
http://www.humankinetics.com/AcuCustom/Sitename/DAM/091/SEp_Main._45.png
How built and economic environments effect health behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades.
Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5-11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18-32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?
Physical activity is the positive approach to weight control
Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action.
Weight control is a lifelong journey. The best time to start is when you are young; the next best time is today. Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action. No other approach is so physiologically sound, so definite, so enjoyable. Action is more psychologically rewarding than avoidance. When you take a walk after dinner, you relax, improve your digestion, enhance your vitality, and burn fat and calories. After the walk, you feel better both physically and emotionally. Problems loom large when you sit and brood, but how quickly they shrink when you undertake a plan of action!
Dieting carries negative connotations of avoidance, deprivation, and punishment. It creates false hopes, contributes to stress, ruins the disposition, causes fatigue, and often leads to increases in body weight and fat. The ups and downs of frequent dieting (weight cycling, or yo-yo dieting) increase the risk of psychopathology, dissatisfaction with life, binge eating, morbidity, and mortality (Brownell and Rodin 1994). This is also true in young women who are dieting for body image, with the additional problem that weight cycling may promote the onset of atherosclerosis (Montani et al. 2006).
The most exciting part of this chapter deals with the extra benefits that you obtain with improved fitness, benefits that exceed the effects of activity. This material, although not new, is finally coming to the attention of public health and fitness professionals. In our estimation, these extra benefits provide the most convincing case for activity and fitness and their relationship to weight control and health.
Finally, we outline activity, food choices (diet), and a lifelong approach to rational weight control.
Some types of exercise are better than others for weight control. As you know, we gradually shift from fat to carbohydrate metabolism as exercise becomes more vigorous. If you want to burn excess fat, consider light to moderate exercise (see table 13.2). Because you cannot sustain extremely vigorous activity for long, total caloric expenditure may not be great. In addition, fat utilization increases over time, with more fat being burned after 30 minutes of exercise. You can continue light to moderate activity for hours without undue fatigue, thereby allowing significant fat metabolism and caloric expenditure.
Incidentally, while we are on the subject of fat metabolism, the best time to exercise for weight control may be in the morning, before breakfast, when you are more likely to burn fat after an overnight fast. So, if you are interested in fat metabolism and weight control, try morning exercise. If that approach doesn't suit your biological clock, don't despair. Exercise always burns calories, so it always contributes to weight control.
Perhaps the best idea is to find an active hobby or sport and make it an essential part of your life. Try woodworking, racquetball, golf, or dancing. Get a canoe or cross-country skis, or start a garden. Dig out the tennis racket and try it. Go ice-skating in winter or roller-skating any time of year. You'll enrich your life and lower your weight at the same time. Of course, you'll look better too!
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/tb13_Main.2.png
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/SEp_Main._331.png
Activity improves cognitive health
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function?
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function? In his book Spark: The Revolutionary New Science of Exercise and the Brain, John Ratey summarizes the positive affect that physical activity has on brain function (Ratey and Hagerman 2008). Current research has even demonstrated that physical activity can stimulate neurogenesis (the growth of new brain cells) while also increasing the number of neural connections (Bekinschtein et al. 2011). A growing body of knowledge shows that youth and adolescents who participate in regular moderate and vigorous physical activity do better at school in terms of academic achievement, attendance, attention, memorization, and integration. They also exhibit fewer disciplinary problems and incidences of attention-deficit/hyperactivity disorder (ADHD) (Gaskill, Miller, and Wambold 2012, Trudeau and Shephard 2008).
These studies make a strong case for increasing physical activity in schools rather than the current trend to reduce recess, cut physical education, and spend more time sitting in the classroom. The understanding that physical activity was related to brain health is not new. Ancient philosophers believed that bodily activity improved brain fitness.Plato, Hippocrates, and many others stressed the mind-body connection throughout their writings, yet it is only recently that both empirical evidence and mechanistic studies are beginning to document the basis for the body-mind connection. Let's take a look at some of the opinions and evidence.
In a study of 482 2nd- through 12th-grade students, we (Gaskill, Miller, and Wambold 2012) evaluated physical activity compared to both grade point average and standardized tests scores. The most active fourth of the students averaged nearly a full grade point higher and did significantly better on standardized tests than the quartile of least active students. The academic achievement gap increased with grade level. By high school, the GPA gap was nearly 1.5 grade points (3.52 for the most active versus 2.14 for the least active). Students in the Naperville, Illinois school district are all required to participate in nearly an hour of daily physical activity, which substantially raises their heart rates. They also placed 1st in the world in science testing and 6th in math. Additionally, their rates of overweight and obesity are less than 10 percent, nearly half of the rate of nearby communities and one-third of the national average (Ratey and Hagerman 2008).
During the last 5 years, more than 100 studies have documented the effect of physical activity or fitness on academic performance (Singh et al. 2012). In a number of studies, up to an hour of physical activity time replaced academic classroom time. In every study, academic performance measures either increased or at least did not decrease, even when time was taken from academic time for physical activity. In addition, attendance improved, and disciplinary referrals and attention deficit were reduced. What is generally not mentioned in these studies are all of the other benefits of physical activity: reduced obesity rates, decreased risk of chronic disease, improved self-efficacy, and all of the other benefits discussed in this book. In animal studies, and using new imaging techniques in humans, scientists have shown that increased physical activity helps our brains to grow new neurons and to increase the connections between neurons (Bekinschtein et al. 2011). This brain growth, termed neurogenesis, was previously believed not to occur in adults. Data suggest that coordinative and sustained aerobic exercise dramatically improve brain function. This is particularly true for youth, but adults and the elderly can also both improve cognition and slow the rates of decline.
The stimulus for neurogenesis and the associated improved memory, integration of information, and attention span that leads to higher cognitive function and academic achievement is the result of a number of hormones and brain chemicals that are increased or decreased by the exercise stimulus. Contracting muscles release growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) and help stimulate blood vessel growth in both the body and the brain. Vascular diameter is enlarged by nitric oxide, increasing blood flow and decreasing hardening of the arteries, even in the brain. Exercise stimulates insulin-like growth factor, thus better regulating insulin while also improving synaptic plasticity in the brain. As blood glucose decreases as a result of exercise, both exercise and lower blood glucose stimulate brain-derived neurotropic factor, which has been termed “Miracle Grow for the brain” by Dr. Ratey (Ratey and Hagerman 2008). Exercise also stimulates a number of neurotransmitters and neurotrophin to stimulate and encourage growth of the hippocampus area of the brain. These effects elevate our mood and reduce our chances for dementia. So, there really is a body-brain connection. Current research shows that an active lifestyle has many positive outcomes in our brains.
In the fall of 2011, the American College of Sports Medicine held the first conference dedicated to how physical activity affects cognition and learning. More than 400 scientists, teachers, administrators, doctors, and politicians attended. The exciting news is that many schools and communities are adapting new policies that encourage or require physical activity on a regular basis for school youth. Those schools are seeing improvements in learning, behavior, attendance, and graduation, as well as decreases in attention-deficit/hyperactivity disorder (ADHD). The following box lists best practices learned at this conference, along with some great resources that parents and school officials can use in order to change their schools.
http://www.humankinetics.com/AcuCustom/Sitename/DAM/091/SEp_Main._45.png
How built and economic environments effect health behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades.
Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5-11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18-32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?
Physical activity is the positive approach to weight control
Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action.
Weight control is a lifelong journey. The best time to start is when you are young; the next best time is today. Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action. No other approach is so physiologically sound, so definite, so enjoyable. Action is more psychologically rewarding than avoidance. When you take a walk after dinner, you relax, improve your digestion, enhance your vitality, and burn fat and calories. After the walk, you feel better both physically and emotionally. Problems loom large when you sit and brood, but how quickly they shrink when you undertake a plan of action!
Dieting carries negative connotations of avoidance, deprivation, and punishment. It creates false hopes, contributes to stress, ruins the disposition, causes fatigue, and often leads to increases in body weight and fat. The ups and downs of frequent dieting (weight cycling, or yo-yo dieting) increase the risk of psychopathology, dissatisfaction with life, binge eating, morbidity, and mortality (Brownell and Rodin 1994). This is also true in young women who are dieting for body image, with the additional problem that weight cycling may promote the onset of atherosclerosis (Montani et al. 2006).
The most exciting part of this chapter deals with the extra benefits that you obtain with improved fitness, benefits that exceed the effects of activity. This material, although not new, is finally coming to the attention of public health and fitness professionals. In our estimation, these extra benefits provide the most convincing case for activity and fitness and their relationship to weight control and health.
Finally, we outline activity, food choices (diet), and a lifelong approach to rational weight control.
Some types of exercise are better than others for weight control. As you know, we gradually shift from fat to carbohydrate metabolism as exercise becomes more vigorous. If you want to burn excess fat, consider light to moderate exercise (see table 13.2). Because you cannot sustain extremely vigorous activity for long, total caloric expenditure may not be great. In addition, fat utilization increases over time, with more fat being burned after 30 minutes of exercise. You can continue light to moderate activity for hours without undue fatigue, thereby allowing significant fat metabolism and caloric expenditure.
Incidentally, while we are on the subject of fat metabolism, the best time to exercise for weight control may be in the morning, before breakfast, when you are more likely to burn fat after an overnight fast. So, if you are interested in fat metabolism and weight control, try morning exercise. If that approach doesn't suit your biological clock, don't despair. Exercise always burns calories, so it always contributes to weight control.
Perhaps the best idea is to find an active hobby or sport and make it an essential part of your life. Try woodworking, racquetball, golf, or dancing. Get a canoe or cross-country skis, or start a garden. Dig out the tennis racket and try it. Go ice-skating in winter or roller-skating any time of year. You'll enrich your life and lower your weight at the same time. Of course, you'll look better too!
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/tb13_Main.2.png
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/SEp_Main._331.png
Activity improves cognitive health
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function?
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function? In his book Spark: The Revolutionary New Science of Exercise and the Brain, John Ratey summarizes the positive affect that physical activity has on brain function (Ratey and Hagerman 2008). Current research has even demonstrated that physical activity can stimulate neurogenesis (the growth of new brain cells) while also increasing the number of neural connections (Bekinschtein et al. 2011). A growing body of knowledge shows that youth and adolescents who participate in regular moderate and vigorous physical activity do better at school in terms of academic achievement, attendance, attention, memorization, and integration. They also exhibit fewer disciplinary problems and incidences of attention-deficit/hyperactivity disorder (ADHD) (Gaskill, Miller, and Wambold 2012, Trudeau and Shephard 2008).
These studies make a strong case for increasing physical activity in schools rather than the current trend to reduce recess, cut physical education, and spend more time sitting in the classroom. The understanding that physical activity was related to brain health is not new. Ancient philosophers believed that bodily activity improved brain fitness.Plato, Hippocrates, and many others stressed the mind-body connection throughout their writings, yet it is only recently that both empirical evidence and mechanistic studies are beginning to document the basis for the body-mind connection. Let's take a look at some of the opinions and evidence.
In a study of 482 2nd- through 12th-grade students, we (Gaskill, Miller, and Wambold 2012) evaluated physical activity compared to both grade point average and standardized tests scores. The most active fourth of the students averaged nearly a full grade point higher and did significantly better on standardized tests than the quartile of least active students. The academic achievement gap increased with grade level. By high school, the GPA gap was nearly 1.5 grade points (3.52 for the most active versus 2.14 for the least active). Students in the Naperville, Illinois school district are all required to participate in nearly an hour of daily physical activity, which substantially raises their heart rates. They also placed 1st in the world in science testing and 6th in math. Additionally, their rates of overweight and obesity are less than 10 percent, nearly half of the rate of nearby communities and one-third of the national average (Ratey and Hagerman 2008).
During the last 5 years, more than 100 studies have documented the effect of physical activity or fitness on academic performance (Singh et al. 2012). In a number of studies, up to an hour of physical activity time replaced academic classroom time. In every study, academic performance measures either increased or at least did not decrease, even when time was taken from academic time for physical activity. In addition, attendance improved, and disciplinary referrals and attention deficit were reduced. What is generally not mentioned in these studies are all of the other benefits of physical activity: reduced obesity rates, decreased risk of chronic disease, improved self-efficacy, and all of the other benefits discussed in this book. In animal studies, and using new imaging techniques in humans, scientists have shown that increased physical activity helps our brains to grow new neurons and to increase the connections between neurons (Bekinschtein et al. 2011). This brain growth, termed neurogenesis, was previously believed not to occur in adults. Data suggest that coordinative and sustained aerobic exercise dramatically improve brain function. This is particularly true for youth, but adults and the elderly can also both improve cognition and slow the rates of decline.
The stimulus for neurogenesis and the associated improved memory, integration of information, and attention span that leads to higher cognitive function and academic achievement is the result of a number of hormones and brain chemicals that are increased or decreased by the exercise stimulus. Contracting muscles release growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) and help stimulate blood vessel growth in both the body and the brain. Vascular diameter is enlarged by nitric oxide, increasing blood flow and decreasing hardening of the arteries, even in the brain. Exercise stimulates insulin-like growth factor, thus better regulating insulin while also improving synaptic plasticity in the brain. As blood glucose decreases as a result of exercise, both exercise and lower blood glucose stimulate brain-derived neurotropic factor, which has been termed “Miracle Grow for the brain” by Dr. Ratey (Ratey and Hagerman 2008). Exercise also stimulates a number of neurotransmitters and neurotrophin to stimulate and encourage growth of the hippocampus area of the brain. These effects elevate our mood and reduce our chances for dementia. So, there really is a body-brain connection. Current research shows that an active lifestyle has many positive outcomes in our brains.
In the fall of 2011, the American College of Sports Medicine held the first conference dedicated to how physical activity affects cognition and learning. More than 400 scientists, teachers, administrators, doctors, and politicians attended. The exciting news is that many schools and communities are adapting new policies that encourage or require physical activity on a regular basis for school youth. Those schools are seeing improvements in learning, behavior, attendance, and graduation, as well as decreases in attention-deficit/hyperactivity disorder (ADHD). The following box lists best practices learned at this conference, along with some great resources that parents and school officials can use in order to change their schools.
http://www.humankinetics.com/AcuCustom/Sitename/DAM/091/SEp_Main._45.png
How built and economic environments effect health behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades.
Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5-11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18-32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?
Physical activity is the positive approach to weight control
Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action.
Weight control is a lifelong journey. The best time to start is when you are young; the next best time is today. Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action. No other approach is so physiologically sound, so definite, so enjoyable. Action is more psychologically rewarding than avoidance. When you take a walk after dinner, you relax, improve your digestion, enhance your vitality, and burn fat and calories. After the walk, you feel better both physically and emotionally. Problems loom large when you sit and brood, but how quickly they shrink when you undertake a plan of action!
Dieting carries negative connotations of avoidance, deprivation, and punishment. It creates false hopes, contributes to stress, ruins the disposition, causes fatigue, and often leads to increases in body weight and fat. The ups and downs of frequent dieting (weight cycling, or yo-yo dieting) increase the risk of psychopathology, dissatisfaction with life, binge eating, morbidity, and mortality (Brownell and Rodin 1994). This is also true in young women who are dieting for body image, with the additional problem that weight cycling may promote the onset of atherosclerosis (Montani et al. 2006).
The most exciting part of this chapter deals with the extra benefits that you obtain with improved fitness, benefits that exceed the effects of activity. This material, although not new, is finally coming to the attention of public health and fitness professionals. In our estimation, these extra benefits provide the most convincing case for activity and fitness and their relationship to weight control and health.
Finally, we outline activity, food choices (diet), and a lifelong approach to rational weight control.
Some types of exercise are better than others for weight control. As you know, we gradually shift from fat to carbohydrate metabolism as exercise becomes more vigorous. If you want to burn excess fat, consider light to moderate exercise (see table 13.2). Because you cannot sustain extremely vigorous activity for long, total caloric expenditure may not be great. In addition, fat utilization increases over time, with more fat being burned after 30 minutes of exercise. You can continue light to moderate activity for hours without undue fatigue, thereby allowing significant fat metabolism and caloric expenditure.
Incidentally, while we are on the subject of fat metabolism, the best time to exercise for weight control may be in the morning, before breakfast, when you are more likely to burn fat after an overnight fast. So, if you are interested in fat metabolism and weight control, try morning exercise. If that approach doesn't suit your biological clock, don't despair. Exercise always burns calories, so it always contributes to weight control.
Perhaps the best idea is to find an active hobby or sport and make it an essential part of your life. Try woodworking, racquetball, golf, or dancing. Get a canoe or cross-country skis, or start a garden. Dig out the tennis racket and try it. Go ice-skating in winter or roller-skating any time of year. You'll enrich your life and lower your weight at the same time. Of course, you'll look better too!
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/tb13_Main.2.png
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/SEp_Main._331.png
Activity improves cognitive health
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function?
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function? In his book Spark: The Revolutionary New Science of Exercise and the Brain, John Ratey summarizes the positive affect that physical activity has on brain function (Ratey and Hagerman 2008). Current research has even demonstrated that physical activity can stimulate neurogenesis (the growth of new brain cells) while also increasing the number of neural connections (Bekinschtein et al. 2011). A growing body of knowledge shows that youth and adolescents who participate in regular moderate and vigorous physical activity do better at school in terms of academic achievement, attendance, attention, memorization, and integration. They also exhibit fewer disciplinary problems and incidences of attention-deficit/hyperactivity disorder (ADHD) (Gaskill, Miller, and Wambold 2012, Trudeau and Shephard 2008).
These studies make a strong case for increasing physical activity in schools rather than the current trend to reduce recess, cut physical education, and spend more time sitting in the classroom. The understanding that physical activity was related to brain health is not new. Ancient philosophers believed that bodily activity improved brain fitness.Plato, Hippocrates, and many others stressed the mind-body connection throughout their writings, yet it is only recently that both empirical evidence and mechanistic studies are beginning to document the basis for the body-mind connection. Let's take a look at some of the opinions and evidence.
In a study of 482 2nd- through 12th-grade students, we (Gaskill, Miller, and Wambold 2012) evaluated physical activity compared to both grade point average and standardized tests scores. The most active fourth of the students averaged nearly a full grade point higher and did significantly better on standardized tests than the quartile of least active students. The academic achievement gap increased with grade level. By high school, the GPA gap was nearly 1.5 grade points (3.52 for the most active versus 2.14 for the least active). Students in the Naperville, Illinois school district are all required to participate in nearly an hour of daily physical activity, which substantially raises their heart rates. They also placed 1st in the world in science testing and 6th in math. Additionally, their rates of overweight and obesity are less than 10 percent, nearly half of the rate of nearby communities and one-third of the national average (Ratey and Hagerman 2008).
During the last 5 years, more than 100 studies have documented the effect of physical activity or fitness on academic performance (Singh et al. 2012). In a number of studies, up to an hour of physical activity time replaced academic classroom time. In every study, academic performance measures either increased or at least did not decrease, even when time was taken from academic time for physical activity. In addition, attendance improved, and disciplinary referrals and attention deficit were reduced. What is generally not mentioned in these studies are all of the other benefits of physical activity: reduced obesity rates, decreased risk of chronic disease, improved self-efficacy, and all of the other benefits discussed in this book. In animal studies, and using new imaging techniques in humans, scientists have shown that increased physical activity helps our brains to grow new neurons and to increase the connections between neurons (Bekinschtein et al. 2011). This brain growth, termed neurogenesis, was previously believed not to occur in adults. Data suggest that coordinative and sustained aerobic exercise dramatically improve brain function. This is particularly true for youth, but adults and the elderly can also both improve cognition and slow the rates of decline.
The stimulus for neurogenesis and the associated improved memory, integration of information, and attention span that leads to higher cognitive function and academic achievement is the result of a number of hormones and brain chemicals that are increased or decreased by the exercise stimulus. Contracting muscles release growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) and help stimulate blood vessel growth in both the body and the brain. Vascular diameter is enlarged by nitric oxide, increasing blood flow and decreasing hardening of the arteries, even in the brain. Exercise stimulates insulin-like growth factor, thus better regulating insulin while also improving synaptic plasticity in the brain. As blood glucose decreases as a result of exercise, both exercise and lower blood glucose stimulate brain-derived neurotropic factor, which has been termed “Miracle Grow for the brain” by Dr. Ratey (Ratey and Hagerman 2008). Exercise also stimulates a number of neurotransmitters and neurotrophin to stimulate and encourage growth of the hippocampus area of the brain. These effects elevate our mood and reduce our chances for dementia. So, there really is a body-brain connection. Current research shows that an active lifestyle has many positive outcomes in our brains.
In the fall of 2011, the American College of Sports Medicine held the first conference dedicated to how physical activity affects cognition and learning. More than 400 scientists, teachers, administrators, doctors, and politicians attended. The exciting news is that many schools and communities are adapting new policies that encourage or require physical activity on a regular basis for school youth. Those schools are seeing improvements in learning, behavior, attendance, and graduation, as well as decreases in attention-deficit/hyperactivity disorder (ADHD). The following box lists best practices learned at this conference, along with some great resources that parents and school officials can use in order to change their schools.
http://www.humankinetics.com/AcuCustom/Sitename/DAM/091/SEp_Main._45.png
How built and economic environments effect health behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades.
Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5-11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18-32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?
Physical activity is the positive approach to weight control
Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action.
Weight control is a lifelong journey. The best time to start is when you are young; the next best time is today. Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action. No other approach is so physiologically sound, so definite, so enjoyable. Action is more psychologically rewarding than avoidance. When you take a walk after dinner, you relax, improve your digestion, enhance your vitality, and burn fat and calories. After the walk, you feel better both physically and emotionally. Problems loom large when you sit and brood, but how quickly they shrink when you undertake a plan of action!
Dieting carries negative connotations of avoidance, deprivation, and punishment. It creates false hopes, contributes to stress, ruins the disposition, causes fatigue, and often leads to increases in body weight and fat. The ups and downs of frequent dieting (weight cycling, or yo-yo dieting) increase the risk of psychopathology, dissatisfaction with life, binge eating, morbidity, and mortality (Brownell and Rodin 1994). This is also true in young women who are dieting for body image, with the additional problem that weight cycling may promote the onset of atherosclerosis (Montani et al. 2006).
The most exciting part of this chapter deals with the extra benefits that you obtain with improved fitness, benefits that exceed the effects of activity. This material, although not new, is finally coming to the attention of public health and fitness professionals. In our estimation, these extra benefits provide the most convincing case for activity and fitness and their relationship to weight control and health.
Finally, we outline activity, food choices (diet), and a lifelong approach to rational weight control.
Some types of exercise are better than others for weight control. As you know, we gradually shift from fat to carbohydrate metabolism as exercise becomes more vigorous. If you want to burn excess fat, consider light to moderate exercise (see table 13.2). Because you cannot sustain extremely vigorous activity for long, total caloric expenditure may not be great. In addition, fat utilization increases over time, with more fat being burned after 30 minutes of exercise. You can continue light to moderate activity for hours without undue fatigue, thereby allowing significant fat metabolism and caloric expenditure.
Incidentally, while we are on the subject of fat metabolism, the best time to exercise for weight control may be in the morning, before breakfast, when you are more likely to burn fat after an overnight fast. So, if you are interested in fat metabolism and weight control, try morning exercise. If that approach doesn't suit your biological clock, don't despair. Exercise always burns calories, so it always contributes to weight control.
Perhaps the best idea is to find an active hobby or sport and make it an essential part of your life. Try woodworking, racquetball, golf, or dancing. Get a canoe or cross-country skis, or start a garden. Dig out the tennis racket and try it. Go ice-skating in winter or roller-skating any time of year. You'll enrich your life and lower your weight at the same time. Of course, you'll look better too!
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/tb13_Main.2.png
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/SEp_Main._331.png
Activity improves cognitive health
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function?
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function? In his book Spark: The Revolutionary New Science of Exercise and the Brain, John Ratey summarizes the positive affect that physical activity has on brain function (Ratey and Hagerman 2008). Current research has even demonstrated that physical activity can stimulate neurogenesis (the growth of new brain cells) while also increasing the number of neural connections (Bekinschtein et al. 2011). A growing body of knowledge shows that youth and adolescents who participate in regular moderate and vigorous physical activity do better at school in terms of academic achievement, attendance, attention, memorization, and integration. They also exhibit fewer disciplinary problems and incidences of attention-deficit/hyperactivity disorder (ADHD) (Gaskill, Miller, and Wambold 2012, Trudeau and Shephard 2008).
These studies make a strong case for increasing physical activity in schools rather than the current trend to reduce recess, cut physical education, and spend more time sitting in the classroom. The understanding that physical activity was related to brain health is not new. Ancient philosophers believed that bodily activity improved brain fitness.Plato, Hippocrates, and many others stressed the mind-body connection throughout their writings, yet it is only recently that both empirical evidence and mechanistic studies are beginning to document the basis for the body-mind connection. Let's take a look at some of the opinions and evidence.
In a study of 482 2nd- through 12th-grade students, we (Gaskill, Miller, and Wambold 2012) evaluated physical activity compared to both grade point average and standardized tests scores. The most active fourth of the students averaged nearly a full grade point higher and did significantly better on standardized tests than the quartile of least active students. The academic achievement gap increased with grade level. By high school, the GPA gap was nearly 1.5 grade points (3.52 for the most active versus 2.14 for the least active). Students in the Naperville, Illinois school district are all required to participate in nearly an hour of daily physical activity, which substantially raises their heart rates. They also placed 1st in the world in science testing and 6th in math. Additionally, their rates of overweight and obesity are less than 10 percent, nearly half of the rate of nearby communities and one-third of the national average (Ratey and Hagerman 2008).
During the last 5 years, more than 100 studies have documented the effect of physical activity or fitness on academic performance (Singh et al. 2012). In a number of studies, up to an hour of physical activity time replaced academic classroom time. In every study, academic performance measures either increased or at least did not decrease, even when time was taken from academic time for physical activity. In addition, attendance improved, and disciplinary referrals and attention deficit were reduced. What is generally not mentioned in these studies are all of the other benefits of physical activity: reduced obesity rates, decreased risk of chronic disease, improved self-efficacy, and all of the other benefits discussed in this book. In animal studies, and using new imaging techniques in humans, scientists have shown that increased physical activity helps our brains to grow new neurons and to increase the connections between neurons (Bekinschtein et al. 2011). This brain growth, termed neurogenesis, was previously believed not to occur in adults. Data suggest that coordinative and sustained aerobic exercise dramatically improve brain function. This is particularly true for youth, but adults and the elderly can also both improve cognition and slow the rates of decline.
The stimulus for neurogenesis and the associated improved memory, integration of information, and attention span that leads to higher cognitive function and academic achievement is the result of a number of hormones and brain chemicals that are increased or decreased by the exercise stimulus. Contracting muscles release growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) and help stimulate blood vessel growth in both the body and the brain. Vascular diameter is enlarged by nitric oxide, increasing blood flow and decreasing hardening of the arteries, even in the brain. Exercise stimulates insulin-like growth factor, thus better regulating insulin while also improving synaptic plasticity in the brain. As blood glucose decreases as a result of exercise, both exercise and lower blood glucose stimulate brain-derived neurotropic factor, which has been termed “Miracle Grow for the brain” by Dr. Ratey (Ratey and Hagerman 2008). Exercise also stimulates a number of neurotransmitters and neurotrophin to stimulate and encourage growth of the hippocampus area of the brain. These effects elevate our mood and reduce our chances for dementia. So, there really is a body-brain connection. Current research shows that an active lifestyle has many positive outcomes in our brains.
In the fall of 2011, the American College of Sports Medicine held the first conference dedicated to how physical activity affects cognition and learning. More than 400 scientists, teachers, administrators, doctors, and politicians attended. The exciting news is that many schools and communities are adapting new policies that encourage or require physical activity on a regular basis for school youth. Those schools are seeing improvements in learning, behavior, attendance, and graduation, as well as decreases in attention-deficit/hyperactivity disorder (ADHD). The following box lists best practices learned at this conference, along with some great resources that parents and school officials can use in order to change their schools.
http://www.humankinetics.com/AcuCustom/Sitename/DAM/091/SEp_Main._45.png
How built and economic environments effect health behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades.
Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5-11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18-32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?
Physical activity is the positive approach to weight control
Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action.
Weight control is a lifelong journey. The best time to start is when you are young; the next best time is today. Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action. No other approach is so physiologically sound, so definite, so enjoyable. Action is more psychologically rewarding than avoidance. When you take a walk after dinner, you relax, improve your digestion, enhance your vitality, and burn fat and calories. After the walk, you feel better both physically and emotionally. Problems loom large when you sit and brood, but how quickly they shrink when you undertake a plan of action!
Dieting carries negative connotations of avoidance, deprivation, and punishment. It creates false hopes, contributes to stress, ruins the disposition, causes fatigue, and often leads to increases in body weight and fat. The ups and downs of frequent dieting (weight cycling, or yo-yo dieting) increase the risk of psychopathology, dissatisfaction with life, binge eating, morbidity, and mortality (Brownell and Rodin 1994). This is also true in young women who are dieting for body image, with the additional problem that weight cycling may promote the onset of atherosclerosis (Montani et al. 2006).
The most exciting part of this chapter deals with the extra benefits that you obtain with improved fitness, benefits that exceed the effects of activity. This material, although not new, is finally coming to the attention of public health and fitness professionals. In our estimation, these extra benefits provide the most convincing case for activity and fitness and their relationship to weight control and health.
Finally, we outline activity, food choices (diet), and a lifelong approach to rational weight control.
Some types of exercise are better than others for weight control. As you know, we gradually shift from fat to carbohydrate metabolism as exercise becomes more vigorous. If you want to burn excess fat, consider light to moderate exercise (see table 13.2). Because you cannot sustain extremely vigorous activity for long, total caloric expenditure may not be great. In addition, fat utilization increases over time, with more fat being burned after 30 minutes of exercise. You can continue light to moderate activity for hours without undue fatigue, thereby allowing significant fat metabolism and caloric expenditure.
Incidentally, while we are on the subject of fat metabolism, the best time to exercise for weight control may be in the morning, before breakfast, when you are more likely to burn fat after an overnight fast. So, if you are interested in fat metabolism and weight control, try morning exercise. If that approach doesn't suit your biological clock, don't despair. Exercise always burns calories, so it always contributes to weight control.
Perhaps the best idea is to find an active hobby or sport and make it an essential part of your life. Try woodworking, racquetball, golf, or dancing. Get a canoe or cross-country skis, or start a garden. Dig out the tennis racket and try it. Go ice-skating in winter or roller-skating any time of year. You'll enrich your life and lower your weight at the same time. Of course, you'll look better too!
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/tb13_Main.2.png
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/SEp_Main._331.png
Activity improves cognitive health
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function?
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function? In his book Spark: The Revolutionary New Science of Exercise and the Brain, John Ratey summarizes the positive affect that physical activity has on brain function (Ratey and Hagerman 2008). Current research has even demonstrated that physical activity can stimulate neurogenesis (the growth of new brain cells) while also increasing the number of neural connections (Bekinschtein et al. 2011). A growing body of knowledge shows that youth and adolescents who participate in regular moderate and vigorous physical activity do better at school in terms of academic achievement, attendance, attention, memorization, and integration. They also exhibit fewer disciplinary problems and incidences of attention-deficit/hyperactivity disorder (ADHD) (Gaskill, Miller, and Wambold 2012, Trudeau and Shephard 2008).
These studies make a strong case for increasing physical activity in schools rather than the current trend to reduce recess, cut physical education, and spend more time sitting in the classroom. The understanding that physical activity was related to brain health is not new. Ancient philosophers believed that bodily activity improved brain fitness.Plato, Hippocrates, and many others stressed the mind-body connection throughout their writings, yet it is only recently that both empirical evidence and mechanistic studies are beginning to document the basis for the body-mind connection. Let's take a look at some of the opinions and evidence.
In a study of 482 2nd- through 12th-grade students, we (Gaskill, Miller, and Wambold 2012) evaluated physical activity compared to both grade point average and standardized tests scores. The most active fourth of the students averaged nearly a full grade point higher and did significantly better on standardized tests than the quartile of least active students. The academic achievement gap increased with grade level. By high school, the GPA gap was nearly 1.5 grade points (3.52 for the most active versus 2.14 for the least active). Students in the Naperville, Illinois school district are all required to participate in nearly an hour of daily physical activity, which substantially raises their heart rates. They also placed 1st in the world in science testing and 6th in math. Additionally, their rates of overweight and obesity are less than 10 percent, nearly half of the rate of nearby communities and one-third of the national average (Ratey and Hagerman 2008).
During the last 5 years, more than 100 studies have documented the effect of physical activity or fitness on academic performance (Singh et al. 2012). In a number of studies, up to an hour of physical activity time replaced academic classroom time. In every study, academic performance measures either increased or at least did not decrease, even when time was taken from academic time for physical activity. In addition, attendance improved, and disciplinary referrals and attention deficit were reduced. What is generally not mentioned in these studies are all of the other benefits of physical activity: reduced obesity rates, decreased risk of chronic disease, improved self-efficacy, and all of the other benefits discussed in this book. In animal studies, and using new imaging techniques in humans, scientists have shown that increased physical activity helps our brains to grow new neurons and to increase the connections between neurons (Bekinschtein et al. 2011). This brain growth, termed neurogenesis, was previously believed not to occur in adults. Data suggest that coordinative and sustained aerobic exercise dramatically improve brain function. This is particularly true for youth, but adults and the elderly can also both improve cognition and slow the rates of decline.
The stimulus for neurogenesis and the associated improved memory, integration of information, and attention span that leads to higher cognitive function and academic achievement is the result of a number of hormones and brain chemicals that are increased or decreased by the exercise stimulus. Contracting muscles release growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) and help stimulate blood vessel growth in both the body and the brain. Vascular diameter is enlarged by nitric oxide, increasing blood flow and decreasing hardening of the arteries, even in the brain. Exercise stimulates insulin-like growth factor, thus better regulating insulin while also improving synaptic plasticity in the brain. As blood glucose decreases as a result of exercise, both exercise and lower blood glucose stimulate brain-derived neurotropic factor, which has been termed “Miracle Grow for the brain” by Dr. Ratey (Ratey and Hagerman 2008). Exercise also stimulates a number of neurotransmitters and neurotrophin to stimulate and encourage growth of the hippocampus area of the brain. These effects elevate our mood and reduce our chances for dementia. So, there really is a body-brain connection. Current research shows that an active lifestyle has many positive outcomes in our brains.
In the fall of 2011, the American College of Sports Medicine held the first conference dedicated to how physical activity affects cognition and learning. More than 400 scientists, teachers, administrators, doctors, and politicians attended. The exciting news is that many schools and communities are adapting new policies that encourage or require physical activity on a regular basis for school youth. Those schools are seeing improvements in learning, behavior, attendance, and graduation, as well as decreases in attention-deficit/hyperactivity disorder (ADHD). The following box lists best practices learned at this conference, along with some great resources that parents and school officials can use in order to change their schools.
http://www.humankinetics.com/AcuCustom/Sitename/DAM/091/SEp_Main._45.png
How built and economic environments effect health behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades.
Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5-11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18-32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?
Physical activity is the positive approach to weight control
Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action.
Weight control is a lifelong journey. The best time to start is when you are young; the next best time is today. Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action. No other approach is so physiologically sound, so definite, so enjoyable. Action is more psychologically rewarding than avoidance. When you take a walk after dinner, you relax, improve your digestion, enhance your vitality, and burn fat and calories. After the walk, you feel better both physically and emotionally. Problems loom large when you sit and brood, but how quickly they shrink when you undertake a plan of action!
Dieting carries negative connotations of avoidance, deprivation, and punishment. It creates false hopes, contributes to stress, ruins the disposition, causes fatigue, and often leads to increases in body weight and fat. The ups and downs of frequent dieting (weight cycling, or yo-yo dieting) increase the risk of psychopathology, dissatisfaction with life, binge eating, morbidity, and mortality (Brownell and Rodin 1994). This is also true in young women who are dieting for body image, with the additional problem that weight cycling may promote the onset of atherosclerosis (Montani et al. 2006).
The most exciting part of this chapter deals with the extra benefits that you obtain with improved fitness, benefits that exceed the effects of activity. This material, although not new, is finally coming to the attention of public health and fitness professionals. In our estimation, these extra benefits provide the most convincing case for activity and fitness and their relationship to weight control and health.
Finally, we outline activity, food choices (diet), and a lifelong approach to rational weight control.
Some types of exercise are better than others for weight control. As you know, we gradually shift from fat to carbohydrate metabolism as exercise becomes more vigorous. If you want to burn excess fat, consider light to moderate exercise (see table 13.2). Because you cannot sustain extremely vigorous activity for long, total caloric expenditure may not be great. In addition, fat utilization increases over time, with more fat being burned after 30 minutes of exercise. You can continue light to moderate activity for hours without undue fatigue, thereby allowing significant fat metabolism and caloric expenditure.
Incidentally, while we are on the subject of fat metabolism, the best time to exercise for weight control may be in the morning, before breakfast, when you are more likely to burn fat after an overnight fast. So, if you are interested in fat metabolism and weight control, try morning exercise. If that approach doesn't suit your biological clock, don't despair. Exercise always burns calories, so it always contributes to weight control.
Perhaps the best idea is to find an active hobby or sport and make it an essential part of your life. Try woodworking, racquetball, golf, or dancing. Get a canoe or cross-country skis, or start a garden. Dig out the tennis racket and try it. Go ice-skating in winter or roller-skating any time of year. You'll enrich your life and lower your weight at the same time. Of course, you'll look better too!
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/tb13_Main.2.png
http://www.humankinetics.com/AcuCustom/Sitename/DAM/092/SEp_Main._331.png
Activity improves cognitive health
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function?
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function? In his book Spark: The Revolutionary New Science of Exercise and the Brain, John Ratey summarizes the positive affect that physical activity has on brain function (Ratey and Hagerman 2008). Current research has even demonstrated that physical activity can stimulate neurogenesis (the growth of new brain cells) while also increasing the number of neural connections (Bekinschtein et al. 2011). A growing body of knowledge shows that youth and adolescents who participate in regular moderate and vigorous physical activity do better at school in terms of academic achievement, attendance, attention, memorization, and integration. They also exhibit fewer disciplinary problems and incidences of attention-deficit/hyperactivity disorder (ADHD) (Gaskill, Miller, and Wambold 2012, Trudeau and Shephard 2008).
These studies make a strong case for increasing physical activity in schools rather than the current trend to reduce recess, cut physical education, and spend more time sitting in the classroom. The understanding that physical activity was related to brain health is not new. Ancient philosophers believed that bodily activity improved brain fitness.Plato, Hippocrates, and many others stressed the mind-body connection throughout their writings, yet it is only recently that both empirical evidence and mechanistic studies are beginning to document the basis for the body-mind connection. Let's take a look at some of the opinions and evidence.
In a study of 482 2nd- through 12th-grade students, we (Gaskill, Miller, and Wambold 2012) evaluated physical activity compared to both grade point average and standardized tests scores. The most active fourth of the students averaged nearly a full grade point higher and did significantly better on standardized tests than the quartile of least active students. The academic achievement gap increased with grade level. By high school, the GPA gap was nearly 1.5 grade points (3.52 for the most active versus 2.14 for the least active). Students in the Naperville, Illinois school district are all required to participate in nearly an hour of daily physical activity, which substantially raises their heart rates. They also placed 1st in the world in science testing and 6th in math. Additionally, their rates of overweight and obesity are less than 10 percent, nearly half of the rate of nearby communities and one-third of the national average (Ratey and Hagerman 2008).
During the last 5 years, more than 100 studies have documented the effect of physical activity or fitness on academic performance (Singh et al. 2012). In a number of studies, up to an hour of physical activity time replaced academic classroom time. In every study, academic performance measures either increased or at least did not decrease, even when time was taken from academic time for physical activity. In addition, attendance improved, and disciplinary referrals and attention deficit were reduced. What is generally not mentioned in these studies are all of the other benefits of physical activity: reduced obesity rates, decreased risk of chronic disease, improved self-efficacy, and all of the other benefits discussed in this book. In animal studies, and using new imaging techniques in humans, scientists have shown that increased physical activity helps our brains to grow new neurons and to increase the connections between neurons (Bekinschtein et al. 2011). This brain growth, termed neurogenesis, was previously believed not to occur in adults. Data suggest that coordinative and sustained aerobic exercise dramatically improve brain function. This is particularly true for youth, but adults and the elderly can also both improve cognition and slow the rates of decline.
The stimulus for neurogenesis and the associated improved memory, integration of information, and attention span that leads to higher cognitive function and academic achievement is the result of a number of hormones and brain chemicals that are increased or decreased by the exercise stimulus. Contracting muscles release growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) and help stimulate blood vessel growth in both the body and the brain. Vascular diameter is enlarged by nitric oxide, increasing blood flow and decreasing hardening of the arteries, even in the brain. Exercise stimulates insulin-like growth factor, thus better regulating insulin while also improving synaptic plasticity in the brain. As blood glucose decreases as a result of exercise, both exercise and lower blood glucose stimulate brain-derived neurotropic factor, which has been termed “Miracle Grow for the brain” by Dr. Ratey (Ratey and Hagerman 2008). Exercise also stimulates a number of neurotransmitters and neurotrophin to stimulate and encourage growth of the hippocampus area of the brain. These effects elevate our mood and reduce our chances for dementia. So, there really is a body-brain connection. Current research shows that an active lifestyle has many positive outcomes in our brains.
In the fall of 2011, the American College of Sports Medicine held the first conference dedicated to how physical activity affects cognition and learning. More than 400 scientists, teachers, administrators, doctors, and politicians attended. The exciting news is that many schools and communities are adapting new policies that encourage or require physical activity on a regular basis for school youth. Those schools are seeing improvements in learning, behavior, attendance, and graduation, as well as decreases in attention-deficit/hyperactivity disorder (ADHD). The following box lists best practices learned at this conference, along with some great resources that parents and school officials can use in order to change their schools.
http://www.humankinetics.com/AcuCustom/Sitename/DAM/091/SEp_Main._45.png
How built and economic environments effect health behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades.
Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5-11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18-32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?
Physical activity is the positive approach to weight control
Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action.
Weight control is a lifelong journey. The best time to start is when you are young; the next best time is today. Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action. No other approach is so physiologically sound, so definite, so enjoyable. Action is more psychologically rewarding than avoidance. When you take a walk after dinner, you relax, improve your digestion, enhance your vitality, and burn fat and calories. After the walk, you feel better both physically and emotionally. Problems loom large when you sit and brood, but how quickly they shrink when you undertake a plan of action!
Dieting carries negative connotations of avoidance, deprivation, and punishment. It creates false hopes, contributes to stress, ruins the disposition, causes fatigue, and often leads to increases in body weight and fat. The ups and downs of frequent dieting (weight cycling, or yo-yo dieting) increase the risk of psychopathology, dissatisfaction with life, binge eating, morbidity, and mortality (Brownell and Rodin 1994). This is also true in young women who are dieting for body image, with the additional problem that weight cycling may promote the onset of atherosclerosis (Montani et al. 2006).
The most exciting part of this chapter deals with the extra benefits that you obtain with improved fitness, benefits that exceed the effects of activity. This material, although not new, is finally coming to the attention of public health and fitness professionals. In our estimation, these extra benefits provide the most convincing case for activity and fitness and their relationship to weight control and health.
Finally, we outline activity, food choices (diet), and a lifelong approach to rational weight control.
Some types of exercise are better than others for weight control. As you know, we gradually shift from fat to carbohydrate metabolism as exercise becomes more vigorous. If you want to burn excess fat, consider light to moderate exercise (see table 13.2). Because you cannot sustain extremely vigorous activity for long, total caloric expenditure may not be great. In addition, fat utilization increases over time, with more fat being burned after 30 minutes of exercise. You can continue light to moderate activity for hours without undue fatigue, thereby allowing significant fat metabolism and caloric expenditure.
Incidentally, while we are on the subject of fat metabolism, the best time to exercise for weight control may be in the morning, before breakfast, when you are more likely to burn fat after an overnight fast. So, if you are interested in fat metabolism and weight control, try morning exercise. If that approach doesn't suit your biological clock, don't despair. Exercise always burns calories, so it always contributes to weight control.
Perhaps the best idea is to find an active hobby or sport and make it an essential part of your life. Try woodworking, racquetball, golf, or dancing. Get a canoe or cross-country skis, or start a garden. Dig out the tennis racket and try it. Go ice-skating in winter or roller-skating any time of year. You'll enrich your life and lower your weight at the same time. Of course, you'll look better too!
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Activity improves cognitive health
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function?
Is it possible that a somatopsychic effect exists in which the health of the body (soma) affects the health of our brain (psychic), thus influencing learning and cognitive function? In his book Spark: The Revolutionary New Science of Exercise and the Brain, John Ratey summarizes the positive affect that physical activity has on brain function (Ratey and Hagerman 2008). Current research has even demonstrated that physical activity can stimulate neurogenesis (the growth of new brain cells) while also increasing the number of neural connections (Bekinschtein et al. 2011). A growing body of knowledge shows that youth and adolescents who participate in regular moderate and vigorous physical activity do better at school in terms of academic achievement, attendance, attention, memorization, and integration. They also exhibit fewer disciplinary problems and incidences of attention-deficit/hyperactivity disorder (ADHD) (Gaskill, Miller, and Wambold 2012, Trudeau and Shephard 2008).
These studies make a strong case for increasing physical activity in schools rather than the current trend to reduce recess, cut physical education, and spend more time sitting in the classroom. The understanding that physical activity was related to brain health is not new. Ancient philosophers believed that bodily activity improved brain fitness.Plato, Hippocrates, and many others stressed the mind-body connection throughout their writings, yet it is only recently that both empirical evidence and mechanistic studies are beginning to document the basis for the body-mind connection. Let's take a look at some of the opinions and evidence.
In a study of 482 2nd- through 12th-grade students, we (Gaskill, Miller, and Wambold 2012) evaluated physical activity compared to both grade point average and standardized tests scores. The most active fourth of the students averaged nearly a full grade point higher and did significantly better on standardized tests than the quartile of least active students. The academic achievement gap increased with grade level. By high school, the GPA gap was nearly 1.5 grade points (3.52 for the most active versus 2.14 for the least active). Students in the Naperville, Illinois school district are all required to participate in nearly an hour of daily physical activity, which substantially raises their heart rates. They also placed 1st in the world in science testing and 6th in math. Additionally, their rates of overweight and obesity are less than 10 percent, nearly half of the rate of nearby communities and one-third of the national average (Ratey and Hagerman 2008).
During the last 5 years, more than 100 studies have documented the effect of physical activity or fitness on academic performance (Singh et al. 2012). In a number of studies, up to an hour of physical activity time replaced academic classroom time. In every study, academic performance measures either increased or at least did not decrease, even when time was taken from academic time for physical activity. In addition, attendance improved, and disciplinary referrals and attention deficit were reduced. What is generally not mentioned in these studies are all of the other benefits of physical activity: reduced obesity rates, decreased risk of chronic disease, improved self-efficacy, and all of the other benefits discussed in this book. In animal studies, and using new imaging techniques in humans, scientists have shown that increased physical activity helps our brains to grow new neurons and to increase the connections between neurons (Bekinschtein et al. 2011). This brain growth, termed neurogenesis, was previously believed not to occur in adults. Data suggest that coordinative and sustained aerobic exercise dramatically improve brain function. This is particularly true for youth, but adults and the elderly can also both improve cognition and slow the rates of decline.
The stimulus for neurogenesis and the associated improved memory, integration of information, and attention span that leads to higher cognitive function and academic achievement is the result of a number of hormones and brain chemicals that are increased or decreased by the exercise stimulus. Contracting muscles release growth factors such as vascular endothelial growth factor (VEGF) and fibroblast growth factor (FGF-2) and help stimulate blood vessel growth in both the body and the brain. Vascular diameter is enlarged by nitric oxide, increasing blood flow and decreasing hardening of the arteries, even in the brain. Exercise stimulates insulin-like growth factor, thus better regulating insulin while also improving synaptic plasticity in the brain. As blood glucose decreases as a result of exercise, both exercise and lower blood glucose stimulate brain-derived neurotropic factor, which has been termed “Miracle Grow for the brain” by Dr. Ratey (Ratey and Hagerman 2008). Exercise also stimulates a number of neurotransmitters and neurotrophin to stimulate and encourage growth of the hippocampus area of the brain. These effects elevate our mood and reduce our chances for dementia. So, there really is a body-brain connection. Current research shows that an active lifestyle has many positive outcomes in our brains.
In the fall of 2011, the American College of Sports Medicine held the first conference dedicated to how physical activity affects cognition and learning. More than 400 scientists, teachers, administrators, doctors, and politicians attended. The exciting news is that many schools and communities are adapting new policies that encourage or require physical activity on a regular basis for school youth. Those schools are seeing improvements in learning, behavior, attendance, and graduation, as well as decreases in attention-deficit/hyperactivity disorder (ADHD). The following box lists best practices learned at this conference, along with some great resources that parents and school officials can use in order to change their schools.
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How built and economic environments effect health behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades.
Environment and Behavior
Our social, economic, built, and even weather environments have changed dramatically over the past three to five decades. Consider that in 1960, nearly 70 percent of adult Americans worked in occupations that required physical labor. Today that number is less than 30 percent. This shift in just the economic environment has resulted in an average daily decrease of 400 to 700 kilocalories of energy expenditure, or the equivalent of walking about 4 to 7 miles (6.5-11 km). It is little wonder that the current guidelines for healthy physical activity levels recommend that we accumulate at least 10,000 steps (about 5 mi, or 8 km) a day to reduce likelihood of chronic disease.
As chapter 12 discusses, simple math suggests that storing only 10 kilocalories a day for a year will result in about a pound of stored fat. This means that the reduction of 400 to 700 kilocalories a day in physical activity would result in weight gains of 40 to 70 pounds (18-32 kg) a year if nutritional intake were constant. Luckily, our physiological systems have some ability to adapt to prevent these great weight shifts. However, too little exercise combined with too much food inevitably results in weight gains.
It is not only our economic environment, but also the built environment that conspires to limit our physical movement. Start to pay attention to the multitude of devices that save you a few kilocalories of effort each time you push a button: your TV remote, automatic car windows, and garage door openers. Consider also the many automatic energy savers that we use without even being aware of it: automatic door openers at many buildings, drive-through windows, escalators, elevators, moving walkways, information obtained by searching the Internet instead of going to the library, and many more. At work, we often use e-mail or the phone to contact colleagues who may be next door or just down the hall rather than walking down to their offices.
The built environment can also be blamed for much more loss of physical activity. Consider how the automobile has replaced walking or biking for many short trips. In 1970, it was estimated that walking and biking accounted for about 52 percent of trips shorter than 2 miles (3 km) for shopping and visiting. That percentage had dropped to under 10 percent in 1995 (Purcher and Leferve 1996), and it is now estimated to be less than 6 percent (CDC 2009). As the next chapter discusses, adding purposeful activity to your daily life is one of the most effective methods to increase your physical activity. Although both are getting older, the authors of this book continue to walk and use their bikes for most activities around town.
Of course, the built environment can be blamed for much of the reliance on the automobile. Many suburbs do not have nearby stores that are easy to walk to. Sidewalks may not exist, or may be inconsistent, making walking difficult or unsafe. People often live far from work, and mass transit may not be available. We all need to evaluate our environment to determine what is possible. You may discover that many opportunities exist. Walking a mile from home to catch a bus that then drops you off a mile from work might be just the purposeful activity to get you going. Walking to a neighborhood store for daily supplies rather than frequently driving to the bigger box store might help you get moving, which will make you feel more energetic. You might consider walking or biking rather than driving to visit friends who live nearby.
The social environment also affects our physical activity. Cultures tend to adapt to social norms. When we see the majority of people driving, sitting, watching television, or using computers, we begin to accept that as normal. As the average waistline gets bigger, our image of normal adapts. Students in our Health and Human Performance class in Missoula conducted a survey, asking other students at the university to view images of people (33% normal weight, 33% overweight, and 33% obese) and rate them as normal, overweight, or obese. The majority of students rated both normal and overweight people as normal and most obese people as either normal or overweight, with few ratings of obese. In our freshman class, where all students complete a body-composition lab, we ask everyone to anonymously self-rate themselves prior to both underwater and skinfold measurement and then, again anonymously, to report their percentage of body fat. Eighty percent of overweight students believed they were normal weight, while 24 percent and 43 percent of obese students rated themselves as normal or overweight, respectively. We obviously have a skewed image of a healthy body composition.
The social environment goes much further than just image. Someone who associates with sedentary friends is likely to be sedentary. Youth emulate their peers and their parents. In a project to measure physical activity in Missoula schools, we used accelerometers for a week to measure physical activity of more than 800 2nd- through 12th-grade students. Physical activity decreased dramatically from elementary school to middle school. Seniors in high school were doing almost no vigorous physical activity. Only one-third were meeting health guidelines for adult physical activity, and fewer than 15 percent were meeting youth guidelines. They had adopted the American culture by the time they finished high school. Of course, this should be no surprise, since they are only doing what they see their peers and role models doing. In order to break this cycle, it is necessary to understand the stages of behavior change.
Sallis studied the most common reasons that adults cite for not adopting more physically active lifestyles (Sallis and Hovell 1990, Sallis et al. 1992). His lists include the following:
- Not enough time to exercise
- Find exercise inconvenient
- Lack self-motivation
- Do not find exercise enjoyable
- Find exercise boring
- Lack confidence in ability to be physically active (low self-efficacy)
- Fear of being injured of have been injured recently
- Lack self-management skills such as goal setting, progress monitoring, or a reward process
- Lack encouragement, support, or companionship from family and friends
- Do not have parks, sidewalks, bicycle trails, or safe pleasant paths convenient to the home or office
Each of us can come up with additional reasons as to why we might not be physically active. Understanding the common barriers to physical activity and your personal beliefs and barriers will help you to develop strategies to become more active. You can start by taking the barriers to being physically active quiz (form 5.1). Once you identify your personal barriers, you can use the strategies provided to begin your personal plan toward an active life. What keeps you from being more active?
Physical activity is the positive approach to weight control
Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action.
Weight control is a lifelong journey. The best time to start is when you are young; the next best time is today. Physical activity is the positive approach to weight control. When you decide to do something about your weight, you are committing to a course of action. No other approach is so physiologically sound, so definite, so enjoyable. Action is more psychologically rewarding than avoidance. When you take a walk after dinner, you relax, improve your digestion, enhance your vitality, and burn fat and calories. After the walk, you feel better both physically and emotionally. Problems loom large when you sit and brood, but how quickly they shrink when you undertake a plan of action!
Dieting carries negative connotations of avoidance, deprivation, and punishment. It creates false hopes, contributes to stress, ruins the disposition, causes fatigue, and often leads to increases in body weight and fat. The ups and downs of frequent dieting (weight cycling, or yo-yo dieting) increase the risk of psychopathology, dissatisfaction with life, binge eating, morbidity, and mortality (Brownell and Rodin 1994). This is also true in young women who are dieting for body image, with the additional problem that weight cycling may promote the onset of atherosclerosis (Montani et al. 2006).
The most exciting part of this chapter deals with the extra benefits that you obtain with improved fitness, benefits that exceed the effects of activity. This material, although not new, is finally coming to the attention of public health and fitness professionals. In our estimation, these extra benefits provide the most convincing case for activity and fitness and their relationship to weight control and health.
Finally, we outline activity, food choices (diet), and a lifelong approach to rational weight control.
Some types of exercise are better than others for weight control. As you know, we gradually shift from fat to carbohydrate metabolism as exercise becomes more vigorous. If you want to burn excess fat, consider light to moderate exercise (see table 13.2). Because you cannot sustain extremely vigorous activity for long, total caloric expenditure may not be great. In addition, fat utilization increases over time, with more fat being burned after 30 minutes of exercise. You can continue light to moderate activity for hours without undue fatigue, thereby allowing significant fat metabolism and caloric expenditure.
Incidentally, while we are on the subject of fat metabolism, the best time to exercise for weight control may be in the morning, before breakfast, when you are more likely to burn fat after an overnight fast. So, if you are interested in fat metabolism and weight control, try morning exercise. If that approach doesn't suit your biological clock, don't despair. Exercise always burns calories, so it always contributes to weight control.
Perhaps the best idea is to find an active hobby or sport and make it an essential part of your life. Try woodworking, racquetball, golf, or dancing. Get a canoe or cross-country skis, or start a garden. Dig out the tennis racket and try it. Go ice-skating in winter or roller-skating any time of year. You'll enrich your life and lower your weight at the same time. Of course, you'll look better too!
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