	There is an emerging understanding of skeletal muscle as a secretory organ, and of myokines as mediators of physical fitness through the practice of regular physical exercise (aerobic exercise and strength training), as well as new awareness of the anti-inflammatory and thus disease prevention aspects of exercise. Different muscle fiber types -slow twitch muscle fibers, oxidative muscle fibers, intermediate twitch muscle fibers, and fast twitch muscle fibers - release different clusters of myokines during contraction. This implies that variation of exercise types, particularly aerobic training/endurance training and muscle contraction against resistance (strength training) may offer differing myokine-induced benefits.