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Definition: exercise from Britannica Concise Encyclopedia

Training of the body to improve health and fitness. Different types have different purposes, including aerobics for heart and respiratory function and weight loss, weight-bearing exercise for bone strength, weight training for muscle strength, and stretching for flexibility. Specific exercises are used in physical medicine and rehabilitation. Benefits include lower blood pressure, higher HDL cholesterol, improved disease resistance, and better general well-being.

Event: exercise

Keywords: exercise

Summary Article: Exercise
From Encyclopedia of Human Development

Exercise is commonly associated with aerobic activity or sustained activity over a period of time that utilizes and strengthens the cardiovascular and pulmonary systems. Aerobic exercise involves repetitive movement of large muscle groups and increased respiration rate. Anaerobic exercise, in contrast, generally involves short duration movements of smaller muscle groups and strength-training exercise, helping to increase muscle mass and build and maintain healthy bones. In the following discussion, the terms physical exercise and physical activity will be used interchangeably to refer to the effects of both aerobic and anaerobic exercise.


The Centers for Disease Control and Prevention (CDC) and the American College of Sports Medicine (ACSM) have provided exercise recommendations for all age groups. Current recommendations focus on healthy, active lifestyles rather than the previous recommendations focusing only on cardiovascular fitness. This is due to recent evidence suggesting that moderate amounts of exercise may contribute to improvements in health and that vigorous exercise is not essential for health enhancement. The CDC recommends that adults engage in at least 30 minutes of moderate intensity exercise (e.g., walking briskly, swimming, or dancing) at least 5 days a week or vigorous activity (e.g., jogging, swimming laps, or high impact aerobics) 3 days a week for 20 minutes. In addition, the CDC recommends that older adults engage in moderate intensity exercise for 30 minutes, 3 to 5 days per week, and also recommends strength training 3 days per week to help increase muscle tone and prevent falls. To further encourage people to increase their activity levels and to recognize their current level of activity, many different activities are provided by the CDC as examples of moderate activity, such as gardening, heavy cleaning, walking, and jogging. The guidelines recommend daily physical activity for adolescents, with moderate to vigorous exercise for at least 20 minutes, 3 days a week. The recommendation for children is 30 to 60 minutes of physical activity or accumulated play on all or most days of the week.


In the United States, less than 40% of adults achieve the recommended amounts of exercise and 25% of adults are not at all active. Participation in regular exercise decreases with age and is more common among men than women. One third of older adults age 65 and older are completely sedentary and engage in no regular exercise. People who exercise regularly are more likely to have higher income, more education, and are more likely to be Caucasian.

Exercise patterns are similar for adolescents and younger adults. Nearly 50% of individuals aged 12 to 21 do not engage in regular vigorous exercise. Exercise activity decreases with age from childhood through adolescence. Exercise levels are greater among young men than young women.

Children and Young Adults

Among children, regular physical exercise has many physical, social, and psychological benefits. During the years of physical growth, regular exercise helps to build strong, healthy bones and protects against the development of osteoporosis. Regular exercise also builds more lean muscle while helping prevent obesity.

Among young adults and children, there is a relationship between engaging in regular physical activity and engaging in other healthy behaviors, such as maintaining a healthy diet. Young adults who are inactive tend to eat fewer fruits and vegetables. In addition, young adults who engage in regular exercise may be less likely to engage in risky behaviors, such as using alcohol and drugs, and may be more likely to stay in school. Research has suggested that regular exercise may lead to an increased capacity for learning in children and adolescents, which may, in turn, improve academic performance.

Regular physical exercise also has been found to promote social interaction and psychological well-being, in particular self-esteem. Physical activity in the form of sports participation provides an opportunity for young adults and children to learn about and experience teamwork, self-discipline, leadership, and socialization.

Interventions have been developed to promote regular physical exercise among children and young adults in an effort to help build healthy habits that will last through adulthood. Factors that predict future physical activity among children and adolescents include male gender, intent to be active, a preference for activity, healthy diet, previous physical activity, access to programs or facilities, and time spent outdoors.


Regular exercise in adulthood helps to prevent chronic illness and premature death and also helps moderate the effects of stress on the body. Stress is associated with the release of hormones such as adrenaline and cortisol. In the case of an acute stressor, the release of these hormones is adaptive, mobilizing the body for action. However, if the stress is chronic in nature, the hormone response may not be adaptive and can contribute to health problems, including immune dysfunction. Stress also may increase cardiovascular reactivity, as reflected by exaggerated blood pressure and heart rate response following the onset of a stressor, and delayed recovery time following the stressor before heart rate and blood pressure return to resting levels.

Regular physical activity may be an effective tool for stress management and can help to reduce the effects of chronic stress on the body by aiding in the regulation of adrenaline and cortisol, regulating immune system functioning, and reducing cardiovascular reactivity. Regular physical exercise may increase immune activation, thus helping to prevent illnesses, both acute and chronic. Research has suggested that the release of endogenous opioids, or natural pain inhibitors, during exercise also may help to modulate immune activity. Among individuals with chronic conditions, such as hypertension or type II diabetes, regular exercise may decrease the need for medication to control the condition.

Regular physical exercise may reduce symptoms of depression or anxiety disorders in adults. Research has shown that regular physical exercise is associated with as much symptom relief as medication or combination of medication and psychological treatment. In addition, depressed individuals who maintain regular exercise show a decreased chance of relapse as compared with medication or combined treatment. Regular physical exercise can also improve self-efficacy, which may improve mood as well. Regular physical exercise in a group setting provides additional social support and may increase the likelihood that the exercise program will be maintained.

Due to the large number of benefits of exercise, many research studies have explored various intervention strategies designed to increase exercise adherence. Cognitive-behavioral strategies have been used, including contingency contracting, self-monitoring, and goal setting, but have met with only limited success. Other strategies that have been utilized include techniques to maintain behavioral change, such as reminder phone calls, and relapse prevention techniques, such as increasing awareness of obstacles and developing adaptive coping techniques. One reason that intervention strategies have had only limited success may be that they need to be individualized to promote and maintain exercise according to the respondent's stage of change.

Older Adults

Among older adults, regular exercise helps to maintain healthy bone mass and reduce the risk of fractures and the risk of falling. Exercise may also improve the ability of older adults to live and function independently and may allow older adults to maintain cognitive skills that otherwise show decline with age. Older adults who engage in regular physical activity may show better performance on measures of executive functioning, verbal fluency, and memory, for example. In addition, imaging studies show that aerobic exercise may protect against age-related brain atrophy, particularly atrophy in the prefrontal cortex.


Health benefits of regular physical exercise include a decreased risk of premature mortality and a decreased risk of developing chronic medical conditions, including type II diabetes, heart disease, high blood pressure, and colon cancer. Regular exercise helps build and maintain healthy bones, muscles, and joints. Exercise also aids older adults in increasing strength, preventing osteoporosis, and reducing risks of falling.

Another benefit of exercise across age groups is the prevention and treatment of obesity. The consequences of obesity for physical health include increased mortality and increased risk of chronic illnesses such as cardiovascular disease, type II diabetes, osteoarthritis, and asthma. Consequences of obesity for psychological health include depression and social stigmatization. Obesity rates are rising across the country in both children and adults. Nearly 61% of adults are either overweight or obese, with a body mass index (BMI, or weight in kg/(height in m)2) greater than or equal to 30. Rates of obesity have nearly tripled for children over the past 30 years, from about 5% to about 15%. The demographic pattern of obesity and overweight is consistent with that of regular exercise, as obesity is more common among individuals with lower socioeconomic status (SES) and exercise is more common among higher SES levels. Therefore, one important benefit of regular exercise is to help promote and maintain healthy weight.


Regular physical exercise is associated with various physical and psychological benefits among all age groups. Physical benefits include building and maintaining healthy bones and muscles, promoting healthy cardiovascular and pulmonary functioning, regulating body weight, and preventing chronic illness and premature mortality. Regular physical exercise is also associated with reduced feelings of depression and anxiety, improved capacity for coping with stress, and enhanced psychological well-being.

Further Readings and References
  • Bouchard, C., Shephard, R. J., & Stephens, T. (Eds.). (1994). Physical activity, fitness, and health: International proceedings and consensus statement. Champaign, IL: Human Kinetics.
  • Dubbert, P. M. Physical activity and exercise: Recent advances and current challenges. Journal of Consulting and Clinical Psychology 70 (3) : 526-536.
  • MacKinnon, L. T. (1992). Exercise and immunity. Champaign, IL: Human Kinetics.
  • Sallis, J. F.; Prochaska, J. J.; Taylor, W. C. A review of correlates of physical activity of children and adolescents. Medicine and Science in Sports and Exercise 32 : 963-975.
  • U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion. (nd(n.d.).). Physical activity for everyone. Available from
  • U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion. (1996). Physical activity and health: A report of the Surgeon General. Atlanta, GA: Author.
  • Fondow, Meghan D. M.
    Emery, Charles F.
    Copyright © 2006 by Sage Publications, Inc.

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