Overview of exercise

[Michiko]

Exercise stimulates tissue change and adaptation (eg, increase in muscle mass and strength, cardiovascular endurance), whereas rest and recovery allow such change and adaptation to occur (1). Recovery from exercise is as important as the exercise stimulus. Regular physical activity reduces the likelihood of medical illness, decreases the incidence of the major causes of death, and improves the overall health and quality of life for patients with most medical conditions.
By increasing muscle mass and strength and fostering cardiovascular endurance, exercise improves functional status for sports and activities of daily living and protects against injury. Specific exercise programs are also commonly prescribed to rehabilitate patients after MI, major surgery, and musculoskeletal injury. Preoperative exercise regimens are prescribed before many elective surgical procedures to enhance postoperative recovery (1). Regardless of indication, recommendations for exercise should be based on 2 main principles:

Goals for activity should be specific to the patient, accounting for motivation, needs, physical ability, and psychology, to maximize the likelihood of patient participation and desired outcome.
Activity should be prescribed in a proper dose to achieve a desired effect. An exercise stimulus should be sufficient for the body to adapt to a higher state of function, to maintain a level of function, or to slow the loss of function, but not so great that it causes injury or nonadherence. More exercise or higher-intensity activity is not always better; too little or too much activity may prevent achievement of desired outcomes.

A prescription for exercise should specify intensity (level of exertion), volume (amount of activity in a session), frequency (number of exercise sessions), and progressive overload (either the amount of increase in one or more of these elements per workout or the actual load). The balance of these elements depends on individual tolerance and physiologic principles (ie, as intensity increases, volume and frequency may need to decrease, whereas as volume increases, intensity may need to decrease). Intensity, volume, and frequency can be increased concurrently, but increases are limited because human tolerance to strain is finite. The objective is to discover the appropriate amount of exercise for optimal benefit in the context of the patient’s goals, health status, and current fitness level. Fixed and traditional generic recommendations (eg, 3 sets of 10 to 12 repetitions, running 30 min 3 times/wk) may be suboptimal because they do not address a person’s specific requirements or capability (ie, people with marked deconditioning require a different program than people with the ability to train at higher intensity levels). Variation in the regimen helps avoid overadaptation (staleness) to the same stimulus as well as minor injuries due to repetitive actions.
Achieving long-term adherence is important and challenging. People differ greatly in their motivation and ability to sustain what they may perceive as arduous activity. To improve adherence, training programs typically start at low intensity levels and gradually increase to the target level. Some people require individually supervised exercise (eg, by a personal trainer), others benefit from the support of organized group activity (eg, an exercise class, group bike ride), and some are able to engage in long-term solitary exercise. For people to sustain motivation over the long term, exercise prescriptions should take into account their needs (eg, leg strengthening exercises for someone wheelchair dependent), what is actually required for them to achieve a particular goal (ie, how realistic the goal is), and preferences (the type of fitness program).
Exercise programs should encompass multiple dimensions of fitness, including

Stretching and flexibility
Aerobic capacity (cardiovascular endurance)
Strength (including muscular endurance and muscle size or structure)
Balance