Inflammation, insulin, and endothelial function in overweight children and adolescents: the role of exercise

OBJECTIVES: To assess subclinical inflammation, fasting insulin, and endothelial function before and after exercise in overweight children and adolescents. STUDY DESIGN: Twenty-five children (body mass index [BMI] >85th percentile) were assessed for brachial artery flow-mediated dilation (FMD), nitroglycerin-induced dilation, C-reactive protein (CRP), lipids, glucose, insulin, oral glucose tolerance, body composition, aerobic fitness (peak oxygen uptake [VO 2 peak]), and blood pressure. Twenty of these persons were equally and randomly assigned to either 8 weeks of stationary cycling or to a non-exercising control group. RESULTS: A baseline correlation was found between CRP and fasting insulin (r = 0.62; P < .001), which remained significant after adjusting for baseline variables (r = 0.53; P < .05). After 8 weeks, significant improvements were observed in the exercise group compared with the control group for VO 2 peak (exercise group = 21.8 +/- 2.1 to 23.2 +/- 1.5 mL/kg/minute vs control group = 23.4 +/- 1.6 to 20.9 +/- 2.2 mL/kg/minute; P < .05), high-density lipoprotein (HDL) cholesterol (exercise group = 1.02 +/- 0.03 to 1.10 +/- 0.04 mmol/L vs control group = 1.08 +/- 0.07 to 0.99 +/- 0.09 mmol/L; P < .05), and FMD area under the curve (AUC) (exercise group = 746 +/- 66 to 919 +/- 94 %*sec vs control group = 731 +/- 102 to 515 +/- 73 %*sec; P < .05). CONCLUSIONS: In overweight children and adolescents, CRP is independently associated with fasting insulin. Eight weeks of aerobic exercise improves fitness, HDL cholesterol, and endothelial function in this group.