Physical Activity and Exercise

Hasan Husni, M.D., Mariana Lazo, M.D., Rita Rastogi Kalyani, M.D., M.H.S.


  • Physical activity: bodily movements produced by the contraction of skeletal muscle that require energy expenditure beyond resting energy expenditure
  • Exercise: planned, structured, and repetitive physical activity performed to improve or to maintain physical fitness, physical performance, or health
  • Physical fitness: includes cardiorespiratory fitness, muscular fitness, and flexibility
  • Intensity of exercise: refers to the level of effort or physiological demand required to perform the activity
  • Metabolic equivalent (MET): unit to describe the energy expended during physical activity. It indexes the intensity of exercise. E.g. sitting at rest (1.0 MET), brisk walking 2.5– 4 mph or water aerobics (3.0- 5.9 MET), jogging/running >4 mph or bicycling >10mph (≥6 MET). Often expressed as MET per minute or MET per hour
  • Maximum heart rate = 220 - age, preferably determined by graded exercise testing (GXT)
  • Classification of physical intensity: light (35-49% of maximum heart rate or 1.1 to 2.9 METs); moderate (50-69% of maximum heart rate or 3.0 to 5.9 METs); vigorous or high (70 - 85% of maximum heart rate or ≥6 METs).
  • Classification of physical activity: Inactive or sedentary (waking behaviors/basic daily activity with low energy expenditure), insufficiently active (less than 150 min moderate-intensity or 75 min vigorous-intensity per week), active (150 – 300 min moderate-intensity physical activity per week), highly active (> 300 min moderate-intensity physical activity per week)
  • Typically, a person doing moderate-intensity activity can speak, but cannot sing during the activity, and a person doing vigorous-intensity activity cannot say more than a few words without pausing for a breath.
  • Aerobic exercise: repeated and continuous movement of the body’s large muscle groups for a sustained period of time (e.g. walking, bicycling, jogging, and swimming). Increases cardiorespiratory fitness. Also called endurance activity or cardio activity.
  • Resistance exercise: activities that use muscular strength to move a weight or work against a resistive load (e.g. weight lifting, push-ups, use of elastic bands). Increases muscular mass, strength and bone mineral density.

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Last updated: June 7, 2021