If there was a magic potion that you could take to increase your energy and help you manage weight, decrease stress, feel better, and decrease the risk of heart disease, cancer, and diabetes, would you be interested? The beneﬁts of regular physical activity include these and many more. It is perhaps our cheapest preventive medicine. To live a wellness lifestyle, you must be physically active. While moderate levels of activity produce improvements in health, physical ﬁtness requires higher-intensity activity and produces greater beneﬁts. Physical ﬁtness is an important component of wellness, because what affects the body ultimately affects the mind. Physical ﬁtness enables you to function at the peak of your capacity physically and mentally—to enjoy life more fully—to be all that you can be.
You want to become more physically ﬁt. How do you begin? We will discusse the beneﬁts of physical activity and how much activity is needed to maintain health. It reviews basic principles of developing physical ﬁtness, gives guidelines for health beneﬁts, and details methods of assessing the healthelated physical ﬁtness components. This enables you to measure your current ﬁtness levels, set goals, and develop a plan for working toward those goals. It will provide you with the information you need to begin a ﬁtness program so that you can reap the beneﬁts for life!
IMPORTANCE OF EXERCISE
The natural peak of ﬁtness occurs at physiological maturity, in the late teens to early twenties. After this, life becomes a slide down the aging curve for sedentary individuals, who gradually lose 1 to 3 percent per year of their cardiorespiratory endurance, muscle mass, ﬂexibility, and so on. If you have observed friends who are older, you have seen that many of them are beginning to show physical deterioration due to lack of exercise: decreasing energy levels, increasing body fat, loss of muscle tone. Our bodies were designed for physical activity, but few occupations provide enough to maintain health or ﬁtness. Homemakers, ofﬁce workers, and students have busy, stressful lives and may feel tired at the end of the day, but they often lack the physical activity vital to tone muscles, stimulate the heart and lungs, or produce a training effect. This has resulted in an epidemic of hypokinetic diseases related to an inactive lifestyle, such as obesity, coronary heart disease, cancer, osteoporosis, and diabetes. Older adults are sometimes erroneously told to “slow down” and “take it easy,” resulting in increasing weakness and accelerated physical decline. Unfortunately, too many people feel that they don’t have time for exercise and are satisﬁed with minimal exertion in their lives. Approximately 250,000 premature deaths per year in the United States can be attributed to lack of exercise. According to Dr. Steven Blair, epidemiologist for the Cooper Institute for Aerobics Research, a sedentary lifestyle is as much a risk factor for disease as are smoking, obesity, and high blood pressure, but inactivity is more prevalent. Inactivity also contributes to the problem of obesity in our country. Over 60 percent of American adults are overweight, and nearly a third are obese. In the last 10 years, adults have shown an average weight gain of nearly 8 pounds per person. Our nation’s children are fatter, too, and about half are not physically active enough for aerobic beneﬁt; this increases their risk of heart disease. Consuming too many calories and not getting enough exercise are to blame. The problem is compounded by the abundance of laborsaving devices, such as remote controls, computers,and riding lawn mowers. Children’s playtime often consists of watching television; surﬁng the Internet; or sports lessons where sitting, standing, or watching consumes a major portion of the time. To make matters worse, although childhood is the best time to develop a lifelong habit of physical activity, many physical education programs face elimination because they are considered a frill when educational budgets are crunched. In a world ﬁlled with labor-saving devices, it is more important than ever to build exercise into our lives for optimal health and well-being.
For young people, levels of physical activity decline sharply through adolescence. Many college students show early signs of hypokinetic disease. If you are concerned about slowly gaining weight from pizza, shakes, and fries, a good ﬁtness program can reverse the trend. If normal daily activities leave you feeling worn out, you can boost your energy with regular exercise 3 to 5 days a week. Because routine activities such as sitting in class, watching TV, and walking across campus seldom require the physical effort needed to develop ﬁtness, we must plan for daily vigorous exercise. The old saying “Use it or lose it” has never been more true.
PHYSICAL ACTIVITY AND HEALTH
We know that many people can improve their health and the quality of their lives with lifelong physical activity, yet about 60 percent of adult Americans are not regularly active and nearly 90 percent need more physical activity to improve their health. Almost half our young people are not vigorously active. To encourage Americans to get moving and reverse the increasing toll of health-care costs related to chronic diseases, the American College of Sports Medicine and the American Heart Association issued a joint recommendation for the quantity of physical activity needed by healthy adults to improve and maintain health:
- To promote and maintain health, all healthy adults ages 18 to 65 should maintain an active lifestyle.
- Include moderately intense aerobic exercise 30 minutes a day, 5 days a week, or vigorously intense aerobic exercise 20 minutes a day, 3 days a week.
- The 30 minutes of moderate-intensity exercise can be accumulated in bouts of 10 minutes or more. Examples of moderate-intensity exercise are given in Figure 3-1. Combinations of moderate- and vigorous-intensity exercise can be done, such as 30 minutes of brisk walking 2 days during the week and 20 minutes of jogging another 2 days.
- Also do 8–10 strength-training exercises, 8–12 repetitions of each, twice a week on nonconsecutive days. This can include lifting weights, calisthenics, elastic bands, etc., using major muscle groups.
- “More is better.” Because greater amounts of physical activity (longer duration or greater intensity) can provide additional health beneﬁts, people who wish to further improve their ﬁtness, reduce risk for chronic disease, or prevent weight gain may beneﬁt by exceeding the minimum recommended amounts of exercise.
- Aerobic activity is needed in addition to the routine light-intensity activities of daily life, such as shopping, mopping, or taking out the trash. However, moderate to vigorous activities performed for more than 10 minutes, such as shoveling snow or walking to work, can count toward the goal.
If you are in the contemplation stage of change, weighing the beneﬁts and costs of an exercise program can help you move to the next stage. If lack of time is a concern, note that a minimum of 1 hour of exercise (20 minutes 3 days) out of 168 hours in your week pays big health dividends:
- Reduces risk of premature death.
- Reduces risk of dying from coronary heart disease and developing high blood pressure, cancer, and diabetes.
- Helps reduce body fat and control weight.
- Helps reduce blood pressure in some people who already have high blood pressure.
- Helps build and maintain healthy bones, muscles,and joints.
- Reduces the risk of developing metabolic syndrome, a deadly combination of three or more of abdominal obesity, insulin resistance, elevated triglicerides, low HDL, and elevated blood pressure.
- Prevents cognitive decline in older individuals and may improve cognitive performance in people of all ages.
- Reduces anxiety and depression and improves mood.
- Promotes psychological well-being.
A landmark study conducted at the Institute for Aerobics Research in Dallas by Steven Blair et al. provides evidence that physical ﬁtness is associated with longevity. In this 8-year study, physical ﬁtness was quantiﬁed by using an exercise tolerance test on a treadmill. The subjects were categorized into physical ﬁtness levels based on the treadmill test. The greatest reduction in risk of death occurred between the low and medium levels of ﬁtness. Therefore, a modest improvement in ﬁtness among the most unﬁt can bring about substantial health beneﬁts.
Healthy People 2010 also contains exercise objectives, which include the following:
- To reduce to 20 percent the proportion of adults who engage in no leisure-time physical activity.
- To increase to 30 percent the proportion of adults who engage regularly in moderate physical activity for at least 30 minutes or more.
Accomplishing these objectives would greatly reduce premature mortality rates. Then, perhaps, these individuals will enjoy a new active lifestyle and begin to see and feel the health beneﬁts of exercise. Eventually, they may invest additional time and energy, increasing the potential to acquire greater benefits from increased levels of activity.
Moderate Physical Activity for Health Promotion
There are differences in the intensity and duration of physical activity needed for health, for physical ﬁtness, and for performance, such as in athletics. What is involved in adopting a moderately active lifestyle?
First, realize that physical activity does not have to be punishing to be beneﬁcial. The emphasis should be on activity of moderate intensity. This would be equivalent to walking approximately 2 miles at a pace of 15 minutes per mile. You don’t have to be soaked with sweat for improvements in health to occur.
Second, exercise does not have to be done all at one time. We know that 20 minutes or more of vigorous exercise is recommended for high-level ﬁtness (full cardiorespiratory beneﬁt), but all activity is beneﬁcial to our health. Something is better than nothing. Incorporate bits of activity every day whenever and wherever you can. For example: Ride your bike to mail a letter; play racquetball, walk, swim, or run at noon; take a walk after dinner; walk to the grocery when you need only a few items. Look for opportunities to add daily activity— get up earlier, use TV commercial time, when working out a problem, when visiting a friend, and so on.
The Activity Pyramid
The Activity Pyramid, like the Food Guide Pyramid, is a guide to help you choose activities to improve your health and ﬁtness level. The activities at the base of the pyramid, such as walking the dog and using the stairs more often, can be built into your everyday life. If you are currently sedentary, this is the place to start. If you are already moderately active, begin a formal exercise program (the second level of the pyramid) at least three times per week. Aerobic exercise is the most beneﬁcial in promoting health beneﬁts and cardiorespiratory ﬁtness. Vigorous recreational sports also promote cardiorespiratory ﬁtness. Extra healthful beneﬁts can be achieved at the third level, which recommends strength exercises at least twice per week to build balanced ﬁtness, especially if you already do aerobic exercise regularly. The fourth level adds ﬂexibility and leisure activities two or three times per week. The top of the pyramid suggests what to do least, including sitting and watching TV.
You are faced with a tremendous challenge. Because you are our nation’s future homemakers, parents, and leaders, the responsibility for the health and well-being of the next generation rests in your hands.You can make an enormous impact on the activity patterns of your children, family, friends, and neighbors by setting a good example. So go to it: Get up off the sofa, turn off the TV, and accept the challenge to enjoy exercise daily.
Encourage your friends and neighbors to get out and work in the garden, walk around the block, mow the lawn, walk the dog, participate in recreational sports (bowling, tennis, golf, softball), and go dancing. Anyone can begin the journey toward wellness with a single step and begin reaping health beneﬁts immediately.
While moderate activity can improve health, physical ﬁtness requires more vigorous exercise to cause long-term beneﬁcial physiological changes. Speciﬁc activity examples are given in Figure 3-1. Next, we look at the components of physical ﬁtness and basic principles of ﬁtness development.
WHAT IS PHYSICAL FITNESS?
Physical ﬁtness is the ability of the body to function at optimal efﬁciency. The ﬁt individual is able to complete the normal routine for the day and still have ample reserve energy to meet the other demands of daily life—recreational sports and other leisure activities—and to handle life’s emergency situations. Physical ﬁtness involves skill-related and health-related components, which are listed below. The skill-related components of ﬁtness are important to athletic success and are not crucial for health. The ﬁve health-related components of ﬁtness are important for health and performance of daily functional activities.
|Reaction time||Body composition|
Probably the most important ﬁtness component is cardiorespiratory endurance (CRE), the ability of the heart, blood vessels, and lungs to deliver oxygen and essential nutrients to the working muscles and remove waste products during vigorous physical activity. Your life depends on the efﬁcient functioning of your cardiorespiratory system. Research shows that vigorous exercise is needed to keep your heart healthy and prevent heart disease. Good CRE is also needed if you want to enjoy running, swimming, cycling, and other vigorous activities to live at the peak of health and enjoy a full life. For more information on CRE.
Muscular strength is the ability of a muscle to exert one maximal force against resistance. Short-duration, highintensity efforts such as moving furniture, lifting a heavy suitcase, and lifting a 100-pound weight one time are examples. Strength is important in sports whether you are hitting a tennis ball, running, jumping, or throwing. Weight training (Chapter 6) is the best way to enhance strength and provides health beneﬁts needed across the life span.
Muscular endurance is the ability of a muscle to exert repeated force against resistance or to sustain muscular contraction. It is characterized by activities of long duration but low intensity, such as doing repetitions of push-ups or sit-ups. Muscular endurance is essential in everyday activities such as housework, yard work, and recreational sports. Muscular strength and endurance tend to decline with age along with activity levels, making it difﬁcult to perform daily activities such as getting in and out of a car and standing up from the ﬂoor. This loss can be delayed and muscular ﬁtness can be maintained by participating in a resistance training program.
Flexibility is movement of a joint through a full range of motion. Flexibility is essential to smooth, efﬁcient movement and may help prevent muscle strains. It is speciﬁc to each joint; you may have ﬂexible shoulders but tight hip ﬂexors or vice versa. Can you sit and touch your toes without bending your knees? This requires hamstring ﬂexibility. You need arm and shoulder ﬂexibility to scratch your back. Women usually have more joint ﬂexibility than men because men have bulkier skeletal muscles. Older adults may have trouble performing routine tasks such as turning to watch trafﬁc while driving and dressing when clothes fasten at the back because ﬂexibility diminishes with age. This loss can be countered if stretching is part of your lifetime exercise program. Chapter 5 has more information about ﬂexibility.
Body composition is the amount of body fat in proportion to fat-free weight. The ratio between body fat and fat-free weight is a better gauge of fatness than is body weight alone. There are various ways to measure body composition, and all are superior to the height/weight chart method. For instance, a height/weight chart may label a 6-foot, 210-pound football player as overweight, when in reality he has only 10 percent body fat, as measured with skinfold calipers. On the other hand, a sedentary person may look okay, but when body composition is analyzed, it is calculated to be 30 percent body fat.
Have your body composition analyzed by a professional. Obesity is both unhealthy and uncomfortable and is associated with increased risk for heart disease, diabetes, high blood pressure, cancer, and joint and lower back problems.
PHYSICAL FITNESS AND WELLNESS
Becoming physically ﬁt is a positive health habit that has a major impact on all dimensions of wellness. It is one area where you can assume control of your lifestyle.
PRINCIPLES OF FITNESS DEVELOPMENT
When a person begins an exercise program, the body adapts over time to the demands placed on it. The beneﬁcial long-term changes that occur with regular exercise depend on several factors. To put together an effective exercise program, it is important to understand several principles of ﬁtness development, including overload, speciﬁcity, reversibility, and individual differences.
Progressive overload is a gradual increase in physical activity, working a muscle group or body system beyond accustomed levels. Overload is perhaps the most important factor in developing physical ﬁtness. When the amount of exercise is gradually increased, the muscle group or system, such as the cardiorespiratory system, gradually adapts, resulting in improved physiological functioning. In addition, a decrease in the severity and a delay in the onset of fatigue occur. If there is insufﬁcient overload, there is no ﬁtness improvement, but too much overload can cause injury. The key to gradual overload is to increase slowly.
To progress in cardiorespiratory exercise, gradually increase the frequency of workouts, starting with three and progressing to ﬁve workouts per week, adding one workout each week. Second, increase time. Start with workouts of 20 minutes (or less, if your ﬁtness is very low), and lengthen the workouts by no more than 10 percent per week. For example, if the conditioning bout is 20 minutes, the next week’s workout can be 22 minutes. Third, increase the workout intensity by no more than 10 percent per week.
The old saying “No pain, no gain!” is inappropriate advice for ﬁtness exercisers. To increase your level of ﬁtness and minimize the risk of overuse injury, follow the prescription factors in the correct order and listen to your body. Don’t rush to get into shape in a few weeks.Exercise is for a lifetime.
The principle of speciﬁcity means that only the muscles or body systems being exercised will show beneﬁcial changes. To improve the cardiorespiratory system, exercise the heart and lungs through aerobic activities; to improve ﬂexibility, do stretching exercises; and to improve muscular strength, lift weights. You cannot strengthen the muscles of the arms by jogging or increase cardiorespiratory ﬁtness by doing yoga. This principle also helps explain why you are “wiped out” after swimming 10 minutes even though you can run for 30 minutes.
The principle of reversibility states that changes occurring with exercise are reversible and that if a person stops exercising, the body will decondition and adapt to the decreased activity level. Rate of ﬁtness loss varies, but if a person stops exercising, a gradual loss of ﬁtness begins within 48 hours. All ﬁtness improvements can be lost within 2 to 4 months. If a person must decrease activity, the greatest beneﬁts can be retained by maintaining intensity while decreasing the frequency or time of exercise. For example, if a person is traveling for 2 weeks and doesn’t have time for the regular 30-minute run,5 days a week, dropping to 20 minutes or 3 days a week at the usual target heart rate (THR) will help maintain training effect beneﬁts.
The principle of individual differences states that people vary in their ability to develop ﬁtness components.Some people ﬁnd that it is relatively easy to buildstrength, but they have to work hard to maintain their desired body composition. Others ﬁnd that it is easier to increase their cardiorespiratory endurance than their ﬂexibility. We differ in our genetic endowment, and there are limits on our ability to improve any particular ﬁtness component. Some have estimated that maximal oxygen uptake can be improved by only about 15 to 30 percent with aerobic exercise. Even that amount of increase can make a tremendous difference in quality of life. Within our genetic endowment, we have potential for improvement. You don’t have to be an Olympic athlete to gain the health beneﬁts of physical activity.
Cross training involves participating in two or more types of exercise in one session or in alternate sessions for balanced ﬁtness. An easy way to start is to vary activities; for example, you could add one swimming session and two weight training days to a three-times-per-week jogging program and stretch daily. Or within one exercise bout you may spend a few minutes warming up on a treadmill, lift weights, do stationary cycling for 20 minutes, and ﬁnish with stretching. See Table 3-2 for cross-training activities. Cross training provides several advantages for the health/ﬁtness exerciser:
- It adds variety to your exercise sessions, preventing boredom and making it easier to stick to an exercise program.
- It provides a greater variety of ﬁtness beneﬁts than does any single activity alone. For example, weight training improves muscular strength and endurance but does little for cardiorespiratory endurance or ﬂexibility. Running increases cardiorespiratory endurance but does little for upper-body strength. Cross training can be used to develop all ﬁve ﬁtness components.
- It reduces the risk of injury because the bones, joints, and muscles are not subjected to the same repetitive stresses of one activity, which leads to overuse injuries (e.g., shin splints from excessive impact).
- Changing activities utilizes muscles differently, promoting muscle symmetry, a balance of strength, and ﬂexibility in opposing muscle groups. Using only one activity tends to cause some muscles to grow strong and their opposing muscles to grow disproportionately weak.
- You may continue to train while allowing an injury to heal by using activities that do not stress the injured area.
- It develops balanced ﬁtness, because optimal performance in any activity usually requires more than one ﬁtness component. For example, a distance runner may beneﬁt from greater strength and anaerobic ﬁtness to run uphill or sprint to the ﬁnish line.