ABSTRACT
In recent years, exercise-induced changes in the anabolic-catabolic hormonal balance and circulating inflammatory cytokines are used frequently by adolescent athletes and their coaches to optimize training (Eliakim and Nemet, 2010). One of the unique features of exercise is that it often leads to simultaneous increase of antagonistic mediators. On one hand, exercise stimulates anabolic components of the growth hormone (GH) → IGF-I (insulin- like growth factor-I) axis. On the other hand, exercise elevates catabolic pro- inflammatory cytokines such as Interlukin-6 (IL-6), IL-1 and tumor necrosis factor-a (Nemet and Eliakim, 2010). The very fine balance between the anabolic and inflammatory/catabolic response to exercise will dictate training effectiveness and the health implications of exercise. If the anabolic response dominates, exercise will probably lead ultimately to increased muscle mass and improved fitness. In contrast, if a greater catabolic response persists for a long duration and/or is combined with inadequate nutrition, this may lead to overtraining.
