ABSTRACT
Exercise-induced changes in anabolic-catabolic hormonal balance and circulating inflammatory cytokines are used frequently by adolescent athletes and coaches to optimize training (Eliakim and Nemet, 2010). A unique feature of exercise is that it leads often to simultaneous increase of antagonistic mediators. For example, exercise stimulates anabolic components of the growth hormone (GH) → IGF-I (insulin-like growth factor-I) axis, and in the same time, it may elevate catabolic pro-inflammatory cytokines such as Interlukin-6 (IL-6), IL-1 and TNF-α (Nemet and Eliakim, 2010). The balance between the anabolic and inflammatory/catabolic response to exercise will dictate training efficiency and the health implications of exercise. If the anabolic response dominates, exercise will probably lead to increased muscle mass and improved fitness. In contrast, a greater catabolic response, particularly if prolonged and/or combined with inadequate nutrition, may lead to overtraining. While hormonal response to a single exercise bout was determined previously, the effect of prolonged training on the response to a single exercise in adolescent athletes was less studied. This is important because studies on the effect of fitness on hormonal responses to exercise yielded conflicting results (Eliakim and Nemet, 2008). Moreover, it is particularly important in adolescent athletes since puberty is characterized by rapid linear and muscle mass growth, and by spontaneous spurt of anabolic hormones. We previously demonstrated that prolonged training was associated with reduced catabolic response to a single practice in elite adolescent female volleyball players (Eliakim et al., 2013). The aim of the present study was to examine the effects of similar training on the hormonal and inflammatory response to a single volleyball practice in elite male adolescent players.
