ABSTRACT
Adaptation occurs in muscles as a consequence of repeated bouts of exercise over a period of time. The form of adaptation can be structural, in which case there is a modification of the actin and myosin, or functional, in which changes occur with respect to mitochondrial density and cytoplasmic enzyme activity. Muscle fibers generate the power and energy for work to be undertaken. Endurance training is the type of training in which the muscle fibers are recruited at lower levels of exercise intensity for a prolonged period of time. The energy demands for this type of activity are derived mainly from aerobic sources and are likely to tax the slow oxidative (SO) and fast oxidative-glycolytic (FOG) fibers rather than the fast glycolytic (FG) fibers. Sprint training involves repeated bouts of high-intensity efforts interspersed with appropriate recovery periods.
