Insulin resistance and cytokines in adolescence: Are weight status and exercise possible moderators?

Increased adiposity has been strongly associated with insulin resistance in youth (Roemmich et al., 2002). Cytokines released by the adipose tissue, such as adiponectin, resistin, interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), appear to link adiposity with insulin resistance in adults (Fernandez-Real and Ricart, 2003). While adiponectin has a negative association with insulin resistance, resistin, TNF-α, and IL-6 appear to have a positive association (Esposito et al., 2003; Fernandez-Real and Ricart, 2003; Silha et al., 2003). Similar relationships may be expected in youth (Huang et al., 2004). Moreover, these relationships may be exacerbated in overweight youth because of the excess of adiposity (Moon et al., 2004). Since these cytokines appear to respond to chronic and acute exercise (Nemet et al., 2002; Esposito et al., 2003), physical activity or aerobic power might modify the association between these cytokines and insulin resistance. This study determined if cytokines (adiponectin, resistin, IL-6 and TNF-α) associated with adiposity are also correlated with insulin resistance in adolescence, and if these relationships are modified by weight status, vigorous physical activity (VPA), or aerobic power.