Physiology and Benefits of Exercise

   What is exercise?

   1. Exercise is an activity that results in contraction of skeletal muscle. The term is usually
   used in reference to any activity that improves physical fitness. Although muscle contraction
   is the common element of all forms of exercise, many other organs and systems are affected,
   for example, the heart and lungs.

   Basic physiology of exercise

   2. Contraction of skeletal muscles, the muscles under conscious control, is the primary
   physiological event during exercise. Because skeletal muscles can actively contract, but are
   not designed to actively lengthen, they are arranged as opposing pairs. As one muscle
   shortens, another is stretched. An example of such a pair of muscles can be observed in the
   upper arm, where the biceps and triceps have opposite actions.

   Anaerobic exercise

   3. This type of exercise involves heavy work by a limited number of muscles, for example
   during weight lifting. These types of activities are maintained only for short intervals, and
   the supply of oxygen is insufficient for aerobic metabolism, resulting in a substantial oxygen
   debt. This exercise increases strength and muscle mass, but is of limited benefit to
   cardiovascular health.

   Aerobic exercise

   4. This type of exercise uses oxygen to keep large muscle groups moving continuously at an
   intensity that can be maintained for at least 20 minutes. This form of exercise uses several
   major muscle groups throughout the body, resulting in greater demands on the cardiovascular
   and respiratory systems to supply oxygen to the working muscles.

   Benefits of exercise

   5. Regular exercise reduces the risk of death due to heart disease and stroke, aids in
   reducing weight, strengthens bones, and enhances immune function. The psychological benefits
   are also broad. It is clear that regular exercise, along with a generally healthy lifestyle,
   is beneficial.