Figure 1. Muscle-organ cross talk mediated by myokines. In response to muscle contraction skeletal muscle expresses and releases myokines into the circulation. The myokines mediate effects locally within the muscle in an autocrine or paracrine manner to increase glucose uptake and fat oxidation. When released into the circulation, the myokines act in a hormone-like fashion mediating peripheral effects including increased hepatic glucose production during exercise, lipolysis in adipose tissue and likely have a preventing effect on tumor growth.