Exercise

Physical Activity and Good Physical Health

Participation in regular physical activity— at least 30 minutes of moderate activity on at least five days per week, or 20 minutes of vigorous physical activity at least three times per week—is critical to sustaining good health. Youth should strive for at least one hour of exercise a day. Regular physical activity has beneficial effects on most (if not all) organ systems, and consequently it helps to prevent a broad range of health problems and diseases. People of all ages, both male and female, derive substantial health benefits from physical activity.

Regular physical activity reduces the risk of developing or dying from some of the leading causes of illness in the United States. Regular physical activity improves health in the following ways:

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

Regular physical activity is 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. Regular physical activity leads to cardiovascular fitness, which decreases the risk of cardiovascular disease mortality in general and coronary artery disease mortality in particular. High blood pressure is a major underlying cause of cardiovascular complications and mortality. Regular physical activity can prevent or delay the development of high blood pressure, and reduces blood pressure in persons with hypertension.

Regular physical activity is also important for maintaining muscle strength, joint structure, joint functioning, and bone health. 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. Among post-menopausal women, exercise, especially muscle strengthening (resistance) activity, may protect against the rapid decline in bone mass. However, data on the effects of exercise on post-menopausal bone loss are not clear-cut and the timing of the intervention (e.g., stage of menopausal transition) can influence the response. Regardless, physical activity including muscle-strengthening exercise appears to protect against falling and fractures among the elderly, probably by increasing muscle strength and balance.In addition, physical activity may be beneficial for many people with arthritis.

Regular physical activity can help improve the lives of young people beyond its effects on physical health. Although research has not been conducted to conclusively demonstrate a direct link between physical activity and improved academic performance, such a link might be expected. Studies have found participation in physical activity increases adolescents’ self-esteem and reduces anxiety and stress. Through its effects on mental health, physical activity may help increase students’ capacity for learning. One study found that spending more time in physical education did not have harmful effects on the standardized academic achievement test scores of elementary school students; in fact, there was some evidence that participation in a two-year health-related physical education program had several significant favorable effects on academic achievement.

Participation in physical activity and sports can promote social well-being, as well as good physical and mental health, among young people. Research has shown that students who participate in interscholastic sports are less likely to be regular and heavy smokers or use drugs, and are more likely to stay in school and have good conduct and high academic achievement. Sports and physical activity programs can introduce young people to skills such as teamwork, self-discipline, sportsmanship, leadership, and socialization. Lack of recreational activity, on the other hand, may contribute to making young people more vulnerable to gangs, drugs, or violence.

Physical Activity and Good Mental Health

Regular physical activity reduces morbidity and mortality from mental health disorders. Mental health disorders pose a significant public health burden in the United States and they are a major cause of hospitalization and disability. Mental health disorders cost approximately $148 billion per year. Potentially, increasing physical activity levels in Americans could substantially reduce medical expenditures for mental health conditions.

In adults with affective disorders, physical activity has a beneficial effect on symptoms of depression and anxiety. Animal research suggests that exercise may stimulate the growth of new brain cells that enhance memory and learning—two functions hampered by depression. Clinical studies have demonstrated the feasibility and efficacy of exercise as a treatment for depression in older men and women. Currently, National Institute of Mental Health (NIMH) investigators are conducting research comparing the effectiveness of home-based and supervised aerobic exercise to the use of antidepressants in relieving depression in these groups, and reducing relapse rates. Other NIMH researchers are studying whether greater exercise levels result in more symptom improvement. Regular physical activity also appears to enhance well-being.

The preventive effects of physical activity on mental disorders are less well studied. Some studies suggest physical activity prevents depressive illness. Future research will clarify the extent to which physical activity may actually protect against the development of depression.

Regular physical activity may also reduce risk of cognitive decline in older adults, though more research is needed to clarify the mechanism of this possible effect. Among people who suffer from mental illness, physical activity appears to improve the ability to perform activities of daily living.

Physical Activity (Along with a Nutritious Diet) is Key to Maintaining Energy Balance and a Healthy Weight

Regular physical activity along with a nutritious diet is key to maintaining a healthy weight. In order to maintain a healthy weight, there must be a balance between calories consumed and calories expended through metabolic and physical activity. Although overweight and obesity are caused by many factors, in most individuals, weight gain results from a combination of excess calorie consumption and inadequate physical activity.

Even though a large portion of a person’s total caloric requirement is used for basal metabolism and processing food, an individual’s various physical activities may account for as much as 15 to 40 percent of the calories he or she burns each day. While vigorous exercise uses calories at a higher rate, any physical activity will burn calories. For example, a 140-pound person can burn 175 calories in 30 minutes of moderate bicycling, and 322 calories in 30 minutes of moderate jogging. The same person can also burn 105 calories by vacuuming or raking leaves for the same amount of time.

The Epidemic of Overweight and Obesity