COMPARISON OF SERUM CYTOKINE LEVELS IN MEN WHO ARE OBESE OR MEN WHO ARE LEAN: EFFECTS OF NONLINEAR PERIODIZED RESISTANCE TRAINING AND OBESITY

This study examined the capacity of nonlinear resistance training (NRT) to alter some cytokines and markers of insulin resistance in men who are obese. An additional aim was to compare these variables between men who are obese and men who are lean. Age- and fitness-matched men who are obese were randomly allocated to NRT (n = 12) and control (CON, n = 10) groups. An age- and fitness-matched control group of lean men (n = 11) were also recruited for baseline comparison. The NRT (12 weeks, 3 d.wk(-1), 5-11 exercises) performed at different intensities (40-95% of 1 repetition maximum) with flexible periodization. Serum insulin, glucose, interleukin (IL)-6, IL-10, IL-17A, and IL-20 levels were measured at baseline and after training. Men who were obese had significantly lower IL-20 and higher glucose, insulin, insulin resistance (homeostasis model assessment, HOMA-IR), IL10, and IL-6 than lean participants at baseline (all, p <= 0.05). There were significant negative correlations between IL-10 with anthropometric markers and HOMA-IR at baseline, whereas these variables were inversely correlated with IL-20. After training, V(over dot)o(2) peak and 1 repetition maximum for bench press and knee extension of the NRT increased significantly compared with CON, which was accompanied by significant reductions in anthropometric markers, insulin and HOMA-IR. IL-6 and IL-17A did not change significantly in response to training, but IL-10 and IL-20 increased significantly compared with baseline. An inverse relationship between the percent IL-20 increase and the percent waist circumference decrease suggests that adipocytes, or other metabolic factors such as glucose, may exert a lowering-effect on IL-20.