Exercise alone reduces insulin resistance in obese children independently of changes in body composition
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Context: The number of obese children with insulin resistance and type 2 diabetes is increasing but the best management strategy is not clear.
Objective: To assess the effect of a structured eight-week exercise training program on insulin resistance and changes in body composition in obese children.
Design: Eight weeks of structured supervised exercise intervention with outcome measures pre- and post- the exercise period.
Subjects: 14 obese children (12.70 +/- 2.32 yr, 8M, 6F) with high fasting insulin levels were enrolled into the study.
Intervention: Eight weeks of supervised circuit-based exercise training, composed of three fully supervised one-hour sessions per week.
Outcome measures: These were assessed pre- and post-training program and included insulin sensitivity (euglycaemic-hyperinsulinaemic clamp studies), fasting insulin and glucose levels, body composition using dual energy X-ray absorptiometry (DEXA) scan, lipid profile and liver function tests.
Results: Insulin sensitivity improved significantly after eight weeks of training (Mlbm 8.20 ± 3.44 to 10.03 ± 4.33 mg/kg/min, P < 0.05). Submaximal exercise heart rate responses were significantly lower following the training (p < 0.05), indicating an improvement in cardiorespiratory fitness. DEXA scans revealed no differences in lean body mass or abdominal fat mass.
Conclusion: An eight-week exercise training program increases insulin sensitivity in obese children, and this improvement occurred in the presence of increased cardiorespiratory fitness but is independent of measurable changes in body composition.