Bright Futures at Georgetown University
Bright Futures in Practice: Physical Activity


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The term "physical activity" describes many forms of movement, including activities that involve the large skeletal muscles.1,2 Activities that involve the small skeletal muscles (e.g., playing board games, drawing, writing) are important, but they do not provide the health benefits of activities that involve the large skeletal muscles and require substantial energy expenditure.
Physical activity is defined by its duration, intensity, and frequency:

  • Duration is the amount of time spent participating in a physical activity session.
  • Intensity is the rate of energy expenditure.
  • Frequency is the number of physical activity sessions during a specific time period (e.g., 1 week).

Types of Physical Activity

Aerobic. Light- to vigorous-intensity physical activity that requires more oxygen than sedentary behavior and thus promotes cardiovascular fitness and other health benefits (e.g., jumping rope, biking, swimming, running; playing soccer, basketball, or volleyball).

Anaerobic. Intense physical activity that is short in duration and requires a breakdown of energy sources in the absence of sufficient oxygen. Energy sources are replenished as an individual recovers from the activity. Anaerobic activity (e.g., sprinting during running, swimming, or biking) requires maximal performance during a brief period.

Lifestyle. Physical activity typically performed on a routine basis (e.g., walking, climbing stairs, mowing or raking the yard), which is usually light to moderate in intensity.

Physical activity play. Play activity that requires sub BFPATO_ILP56 stantial energy expenditure (e.g., playing tag, jumping rope).

Play. Activity with flexible rules, usually self-selected, for the purpose of having fun.

Sports. Physical activity that involves competition, scorekeeping, rules, and an outcome that cannot be predetermined. Sports are usually divided into several categories, such as individual (e.g., gymnastics), dual (e.g., tennis), and team (e.g., basketball).

Weight-bearing. Physical activity that requires people to move their own weight. Weight-bearing activity (e.g., jumping rope, walking, gymnastics, playing volleyball) contributes to the growth of healthy bones in children and adolescents.


Exercise consists of activities that are planned and structured, and that maintain or improve one or more of the components of physical fitness.1 "Physical activity" and "exercise" are often used interchangeably. However, "physical activity" suggests a wide variety of activities that promote health and well-being, whereas "exercise" is often associated with fitness maintenance or improvement only. To achieve specific fitness and performance goals, people must focus on the duration, intensity, and frequency of exercise sessions.

Types of Exercise

Calisthenics. Isotonic muscle-fitness exercise that overloads muscles (e.g., pushups, side leg raises, abdominal curl-ups) by forcing the muscles to work at a higher level than usual.

Flexibility (stretching). Exercise designed to stretch muscles and tendons to increase joint flexibility or range of motion (e.g., trying to touch the floor with the hands while the legs are nearly straight, stretching an arm upward while standing and leaning to the opposite side). Specific flexibility exercises need to be done for each part of the body.

Isokinetic. Muscle-fitness exercise in which the speed of movement is usually controlled, allowing maximal force to be exerted throughout the full range of movement.

Isometric. Muscle-fitness exercise in which the amount of force equals the amount of resistance, so that no movement occurs (e.g., pushing against a door frame while standing in a doorway).

Isotonic. Muscle-fitness exercise (e.g., weightlifting) in which the amount of force exerted is constant throughout the range of motion, including muscle shortening (concentric contractions) and muscle lengthening (eccentric contractions).

Muscle-fitness. Exercise designed to build muscle strength and endurance by overloading the muscles; also called progressive resistance exercise (PRE). Common forms of muscle fitness exercise include isokinetic, isometric, and isotonic. Specific exercises need to be done for each major muscle group.


Participating in physical activity is beneficial to people of all ages. Physical activity contributes to fitness, a state in which people's health characteristics and behaviors enhance the quality of their lives.4

Types of Fitness

Physical fitness. A set of physical attributes related to a person's ability to perform physical activity successfully, without undue strain and with a margin of safety.1

Health-related physical fitness. A physiological state of well-being that reduces the risk of hypokinetic disease (i.e., disease resulting from abnormally decreased mobility or abnormally decreased motor function or activity); a basis for participation in sports; and a vigor for the tasks of daily living.5 Components include cardiorespiratory endurance, muscle strength and endurance, flexibility, and body composition.

Skill-related physical fitness. Common components of physical fitness (e.g., agility, balance, coordination, speed, power, reaction time) that enable participation in sports and other physical activities; also called performance or motor fitness.6


  1. Caspersen CJ, Powell KE, Christensen GM. 1985. Physical activity, exercise, and physical fitness: Definitions and distinctions for health-related research. Public Health Reports 100(2):126­131.
  2. Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion; President's Council on Physical Fitness and Sports. 1996. Physical Activity and Health: A Report of the Surgeon General. Washington, DC: Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion; President's Council on Physical Fitness and Sports.
  3. Pellegrini AD, Smith PK. 1998. Physical activity play: The nature and function of a neglected aspect of playing. Child Development 69(3):577­598.
  4. Franks BD, Howley ET. 1998. Fitness Leader's Handbook (2nd ed.). Champaign, IL: Human Kinetics.
  5. Anschel MH, Freedson P, Hamill J, Haywood K, Horvat M, Plowman SA. 1991. Dictionary of the Sport and Exercise Sciences. Champaign, IL: Human Kinetics.
  6. Corbin CB, Lindsey R, Welk G, Corbin W, Welk K. 2000. Concepts of Physical Fitness: Active Lifestyles for Wellness (10th ed.). Dubuque, IA: McGraw-Hill Higher Education.

Suggested Reading

Bouchard C, Shepard RJ, Stephens T, eds. 1994. Physical Activity, Fitness, and Health: International Proceedings and Consensus Statement. Champaign, IL: Human Kinetics.

Pate RR, Pratt M, Blair SN, Haskell WL, Macera CA, et al. 1995. Physical activity and public health: A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. Journal of the American Medical Association 273(5):402­407.


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