The response of circulating omentin-1 concentration to 16-week exercise training in male children with obesity

OBJECTIVES: The purpose of the present study was to investigate the effects of the 16-week exercise training program on serum omentin-1 in relation to change in insulin resistance in obese male children. METHODS: Thirty-two obese male children, aged 9-12 years, were randomly assigned into Exercise Group (ExG; n = 16) and Control Group (CG; n = 16). ExG participated in a 16-week exercise training program which combined various forms of aerobic activities and resistance training. Body composition, body mass index (BMI), waist circumference (WC), fasting glucose and insulin, homeostasis model assessment estimate of insulin resistance (HOMA2-IR), blood lipids and serum omentin-1 were assessed before and after 16 weeks of training. RESULTS: Exercise training significantly decreased body mass (7.5%), BMI (7.6%), WC (4.3%), body fat % (15%), fasting insulin (18.5%), total cholesterol (TC) (5.4%), low-density lipoprotein cholesterol (LDL-C) (17%) and triglyceride (TG) (7.4%) compared to CG. Between-groups comparison showed a considerable exercise-induced upregulation in omentin-1 (ES = 89; P < 0.05) levels. Furthermore, in ExG serum omentin-1 levels were significantly increased from 24.5 ± 8.4 to 35.9 ± 9.3 ng/ml (45%; P < 0.001) after the training program, which was accompanied with significantly decreased fasting insulin (P < 0.001). The changes in omentin-1 concentrations correlated with the changes in BMI (r = -0.67, P < 0.001), WC (r = -0.62, P = 0.002), body fat % (r = -0.50, P = 0.004), insulin (r = -0.65, P = 0.001), HOMA2-IR (r = -0.60, P = 0.004), TC (r = -0.53, P = 0.004) and LDL-C (r = -0.51, P = 0.004) in ExG. BMI (β = -0.50, P = 0.009) and fasting insulin (β = -0.54, P = 0.006) changes were found to be independent predictors of omentin-1 increment in multiple regression analysis. CONCLUSION: Exercise training resulted in a significant increase in serum omentin-1 concentrations in children with obesity. The findings suggest that exercise-induced changes in omentin-1 may be associated with the beneficial effects of exercise on reduced insulin and weight lost.