Aerobic exercise training improves insulin sensitivity without changes in body weight, body fat, adiponectin, and inflammatory markers in overweight and obese girls

The aim of this study was to examine the effect of aerobic exercise training on insulin sensitivity in overweight and obese girls. Nineteen overweight and obese girls (mean ± SD: age, 13.1 ± 1.8 years; body mass index, 26.8 ± 3.9 kg/m²) volunteered for this study. Body composition (dual-energy x-ray absorptiometry), insulin sensitivity (oral glucose tolerance test and homeostasis model assessment estimate of insulin resistance; n = 15), adiponectin, C-reactive protein (CRP), interleukin (IL) 6, insulin-like growth factor-1, soluble intercellular adhesion molecule-1 and soluble vascular cell adhesion molecule-1 serum levels, and blood lipids and lipoproteins were assessed before and after 12 weeks of aerobic training. Cardiorespiratory fitness increased by 18.8% (P < .05) as a result of training. The area under the insulin concentration curve (insulin area under the curve) decreased by 23.3% (12 781.7 ± 7454.2 vs 9799.0 ± 4918.6 μU·min/mL before and after intervention, respectively; P = .03). Insulin sensitivity was improved without changes in body weight (preintervention, 67.9 ± 14.5 kg; postintervention, 68.3 ± 14.0 kg) or percent body fat (preintervention, 41.4% ± 4.8%; postintervention, 40.7% ± 5.2%). The lower limb fat-free mass increased by 6.2% (P < .01) as a result of training, and changes in lower limb fat-free mass were correlated with changes in the insulin area under the curve (r = -.68; P < .01). Serum adiponectin, IL-6, and CRP concentrations did not change (preintervention vs postintervention: adiponectin, 9.57 ± 3.01 vs 9.08 ± 2.32 μg/mL; IL-6, 1.67 ± 1.29 vs 1.65 ± 1.25 pg/mL, CRP, 3.21 ± 2.48 vs 2.73 ± 1.88 mg/L) whereas insulin-like growth factor-1 was lower after training (preintervention, 453.8 ± 159.3 ng/mL; postintervention, 403.2 ± 155.1 ng/mL; P < .05). In conclusion, 12 weeks of aerobic training improved insulin sensitivity in overweight and obese girls without change in body weight, percent body fat, and circulating concentrations of adiponectin, IL-6, CRP, and other inflammatory markers. These findings suggest that increased physical activity may ameliorate the metabolic abnormalities associated with obesity in children with a mechanism other than the parameters cited earlier.