A NEW VIEW OF PHYSICAL ACTIVITY:

This report brings together, for the first time, what has been learned about physical activity and health from decades of research. Among its major findings:

• People who are usually inactive can improve their health and well-being by becoming even moderately active on a regular basis.
• Physical activity need not be strenuous to achieve health benefits.
• Greater health benefits can be achieved by increasing the amount (duration, frequency, or intensity) of physical activity.

THE BENEFITS OF REGULAR PHYSICAL ACTIVITY:

Regular physical activity that is performed on most days of the week reduces the risk of developing or dying from some of the leading causes of illness and death in the United States. Regular physical activity improves health in the following ways:

• Reduces the risk of dying prematurely.
• Reduces the risk of dying from heart disease.
• Reduces the risk of developing diabetes.
• Reduces the risk of developing high blood pressure.
• Helps reduce blood pressure in people who already have high blood pressure.
• Reduces the risk of developing colon cancer.
• Reduces feelings of depression and anxiety.
• Helps control weight.
• Helps build and maintain healthy bones, muscles, and joints.
• Helps older adults become stronger and better able to move about without falling.
• Promotes psychological well-being.

A MAJOR PUBLIC HEALTH CONCERN:

Given the numerous health benefits of physical activity, the hazards of being inactive are clear. Physical inactivity is a serious, nationwide problem. Its scope poses a public health challenge for reducing the national burden of unnecessary illness and premature death.

WHAT IS A MODERATE AMOUNT OF PHYSICAL ACTIVITY?

As the examples listed in the box show, a moderate amount of physical activity* can be achieved in a variety of ways. People can select activities that they enjoy and that fit into their daily lives. Because amount of activity is a function of duration, intensity, and frequency, the same amount of activity can be obtained in longer sessions of moderately intense activities (such as brisk walking) as in shorter sessions of more strenuous activities (such as running):

EXAMPLES OF MODERATE AMOUNTS OF ACTIVITY:

Less Vigorous, More Time

• Washing and waxing a car for 45-60 minutes
• Washing windows or floors for 45-60 minutes
• Playing volleyball for 45 minutes
• Playing touch football for 30-45 minutes
• Gardening for 30-45 minutes
• Wheeling self in wheelchair for 30-40 minutes
• Walking 1 3/4 miles in 35 minutes (20 min/mile)
• Basketball (shooting baskets) for 30 minutes
• Bicycling 5 miles in 30 minutes
• Dancing fast (social) for 30 minutes
• Pushing a stroller 1 1/2 miles in 30 minutes
• Raking leaves for 30 minutes
• Walking 2 miles in 30 minutes (15 min/mile)
• Water aerobics for 30 minutes
• Swimming laps for 20 minutes
• Wheelchair basketball for 20 minutes
• Basketball (playing a game) for 15-20 minutes
• Bicycling 4 miles in 15 minutes
• Jumping rope for 15 minutes
• Running 1 1/2 miles in 15 minutes (10 min/mile)
• Shoveling snow for 15 minutes
• Stairwalking for 15 minutes

More Vigorous, Less Time

* A moderate amount of physical activity is roughly equivalent to physical activity that uses approximately 150 Calories (kcal) of energy per day, or 1,000 Calories per week.

+ Some activities can be performed at various intensities; the suggested durations correspond to expected intensity of effort.

PRECAUTIONS FOR A HEALTHY START:

To avoid soreness and injury, individuals contemplating an increase in physical activity should start out slowly and gradually build up to the desired amount to give the body time to adjust. People with chronic health problems, such as heart disease, diabetes, or obesity, or who are at high risk for these problems should first consult a physician before beginning a new program of physical activity. Also, men over age 40 and women over age 50 who plan to begin a new vigorous physical activity program should consult a physician first to be sure they do not have heart disease or other health problems.

STATUS OF THE NATION - A NEED FOR CHANGE:

Adults:

• More than 60 percent of adults do not achieve the recommended amount of regular physical activity. In fact, 25 percent of all adults are not active at all.
• Inactivity increases with age and is more common among women than men and among those with lower income and less education than among those with higher income or education

Adolescents and Young Adults:

Nearly half of young people aged 12-21 are not vigorously active on a regular basis.

• Physical activity declines dramatically with age during adolescence.
• Female adolescents are much less physically active than male adolescents.

High School Students:

• In high school, enrollment in daily physical education classes dropped from 42 percent in 1991 to 25 percent in 1995.
• Only 19 percent of all high school students are physically active for 20 minutes or more in physical education classes every day during the school week.

IDEAS FOR IMPROVEMENT:

This report identifies promising ways to help people include more physical activity in their daily lives.

• Well-designed programs in schools to increase physical activity in physical education classes have been shown to be effective.
• Carefully planned counseling by health care providers and worksite activity programs can increase individuals' physical activity levels.
• Promising approaches being tried in some communities around the nation include opening school buildings and shopping malls for walking before or after regular hours, as well as building bicycle and walking paths separated from automobile traffic. Revising building codes to require accessible stairwells is another idea that has been suggested

SPECIAL MESSAGES FOR SPECIAL POPULATIONS:

Older Adults

No one is too old to enjoy the benefits of regular physical activity. Of special interest to older adults is evidence that muscle-strengthening exercises can reduce the risk of falling and fracturing bones and can improve the ability to live independently.

Parents

Parents can help their children maintain a physically active lifestyle by providing encouragement and opportunities for physical activity. Family events can include opportunities for everyone in the family to be active.

Teenagers

Regular physical activity improves strength, builds lean muscle, and decreases body fat. It can build stronger bones to last a lifetime.

Dieters

Regular physical activity burns Calories and preserves lean muscle mass. It is a key component of any weight loss effort and is important for controlling weight.

People with High Blood Pressure

Regular physical activity helps lower blood pressure.

People Feeling Anxious, Depressed, or Moody

Regular physical activity improves mood, helps relieve depression, and increases feelings of well-being.

People with Arthritis

Regular physical activity can help control joint swelling and pain. Physical activity of the type and amount recommended for health has not been shown to cause arthritis.

People with Disabilities

Regular physical activity can help people with chronic, disabling conditions improve their stamina and muscle strength and can improve psychological well-being and quality of life by increasing the ability to perform activities of daily life.

THE EFFECTS OF PHYSICAL ACTIVITY ON HEALTH AND DISEASE

Overall Mortality

• Higher levels of regular physical activity are associated with lower mortality rates for both older and younger adults.
• Even those who are moderately active on a regular basis have lower mortality rates than those who are least active.

Cardiovascular Diseases

• Regular physical activity or cardiorespiratory fitness decreases the risk of cardiovascular disease mortality in general and of coronary heart disease mortality in particular. Existing data are not conclusive regarding a relationship between physical activity and stroke.
• The level of decreased risk of coronary heart disease attributable to regular physical activity is similar to that of other lifestyle factors, such as keeping free from cigarette smoking.
• Regular physical activity prevents or delays the development of high blood pressure, and exercise reduces blood pressure in people with hypertension.

Cancer

• Regular physical activity is associated with a decreased risk of colon cancer.
• There is no association between physical activity and rectal cancer. Data are too sparse to draw conclusions regarding a relationship between physical activity and endometrial, ovarian, or testicular cancers.
• Despite numerous studies on the subject, existing data are inconsistent regarding an association between physical activity and breast or prostate cancers.

Non-Insulin-Dependent Diabetes Mellitus

• Regular physical activity lowers the risk of developing non-insulin-dependent diabetes mellitus.

Osteoarthritis

• Regular physical activity is necessary for maintaining normal muscle strength, joint structure, and joint function. In the range recommended for health, physical activity is not associated with joint damage or development of osteoarthritis and may be beneficial for many people with arthritis.
• Competitive athletics may be associated with the development of osteoarthritis later in life, but sports-related injuries are the likely cause.

Osteoporosis

• Weight-bearing physical activity is essential for normal skeletal development during childhood and adolescence and for achieving and maintaining peak bone mass in young adults.
• It is unclear whether resistance- or endurance-type physical activity can reduce the accelerated rate of bone loss in postmenopausal women in the absence of estrogen replacement therapy.

Falling

• There is promising evidence that strength training and other forms of exercise in older adults preserve the ability to maintain independent living status and reduce the risk of falling.

Obesity

• Low levels of activity, resulting in fewer kilocalories used than consumed, contribute to the high prevalence of obesity in the United States.
• Physical activity may favorably affect body fat distribution.

Mental Health

• Physical activity appears to relieve symptoms of depression and anxiety and improve mood.
• Regular physical activity may reduce the risk of developing depression, although further research is required on this topic.

Health-Related Quality of Life

• Physical activity appears to improve health-related quality of life by enhancing psychological well-being and by improving physical functioning in persons compromised by poor health.

Adverse Effects

• Most musculoskeletal injuries related to physical activity are believed to be preventable by gradually working up to a desired level of activity and by avoiding excessive amounts of activity.
• Serious cardiovascular events can occur with physical exertion, but the net effect of regular physical activity is a lower risk of mortality from cardiovascular disease.

PATTERNS AND TRENDS IN PHYSICAL ACTIVITY

Adults

• Approximately 15 percent of U.S. adults engage regularly (3 times a week for at least 20 minutes) in vigorous physical activity during leisure time.
• Approximately 22 percent of adults engage regularly (5 times a week for at least 30 minutes) in sustained physical activity of any intensity during leisure time.
• About 25 percent of adults report no physical activity at all in their leisure time.
• Physical inactivity is more prevalent among women than men, among blacks and Hispanics than whites, among older than younger adults, and among the less affluent than the more affluent.
• The most popular leisure-time physical activities among adults are walking and gardening or yard work.

Adolescents and Young Adults

• Only about one-half of U.S. young people (ages 12-21 years) regularly participate in vigorous physical activity. One-fourth report no vigorous physical activity.
• Approximately one-fourth of young people walk or bicycle (i.e., engage in light to moderate activity) nearly every day.
• About 14 percent of young people report no recent vigorous or light to moderate physical activity. This indicator of inactivity is higher among females than males and among black females than white females.
• Males are more likely than females to participate in vigorous physical activity, strengthening activities, and walking or bicycling.
• Participation in all types of physical activity declines strikingly as age or grade in school increases.
• Among high school students, enrollment in physical education remained unchanged during the first half of the 1990s. However, daily attendance in physical education declined from approximately 42 percent to 25 percent.
• The percentage of high school students who were enrolled in physical education and who reported being physically active for at least 20 minutes in physical education classes declined from approximately 81 percent to 70 percent during the first half of this decade.
• Only 19 percent of all high school students report being physically active for 20 minutes or more in daily physical education classes.

CONCLUSION

Despite common knowledge that exercise is healthful, more than 60 percent of American adults are not regularly active, and 25 percent of the adult population are not active at all. Moreover, although many people have enthusiastically embarked on vigorous exercise programs at one time or another, most do not sustain their participation. Clearly, the processes of developing and maintaining healthier habits are as important to study as the health effects of these habits.

The effort to understand how to promote more active lifestyles is of great importance to the health of this nation. Although the study of physical activity determinants and interventions is at an early stage, effective programs to increase physical activity have been carried out in a variety of settings, such as schools, physicians' offices, and worksites. Determining the most effective and cost-effective intervention approaches is a challenge for the future. Fortunately, the United States has skilled leadership and institutions to support efforts to encourage and assist Americans to become more physically active. Schools, community agencies, parks, recreational facilities, and health clubs are available in most communities and can be more effectively used in these efforts.

School-based interventions for youth are particularly promising, not only for their potential scope - almost all young people between the ages of 6 and 16 years attend school - but also for their potential impact. Nearly half of young people 12-21 years of age are not vigorously active; moreover, physical activity sharply declines during adolescence. Childhood and adolescence may thus be pivotal times for preventing sedentary behavior among adults by maintaining the habit of physical activity throughout the school years. School-based interventions have been shown to be successful in increasing physical activity levels. With evidence that success in this arena is possible, every effort should be made to encourage schools to require daily physical education in each grade and to promote physical activities that can be enjoyed throughout life.

Outside the school, physical activity programs and initiatives face the challenge of a highly technological society that makes it increasingly convenient to remain sedentary and that discourages physical activity in both obvious and subtle ways. To increase physical activity in the general population, it may be necessary to go beyond traditional efforts. This report highlights some concepts from community initiatives that are being implemented around the country. It is hoped that these examples will spark new public policies and programs in other places as well. Special efforts will also be required to meet the needs of special populations, such as people with disabilities, racial and ethnic minorities, people with low income, and the elderly. Much more information about these important groups will be necessary to develop a truly comprehensive national initiative for better health through physical activity. Challenges for the future include identifying key determinants of physically active lifestyles among the diverse populations that characterize the United States (including special populations, women, and young people) and using this information to design and disseminate effective programs.