Exercise Alone Reduces Insulin Resistance in Obese Children Independently of Changes in Body Composition

Liverpool John Moores University, Liverpool, England, United Kingdom
Journal of Clinical Endocrinology & Metabolism (Impact Factor: 6.21). 11/2007; 92(11):4230-5. DOI: 10.1210/jc.2007-0779
Source: PubMed


The number of obese children with insulin resistance and type 2 diabetes is increasing, but the best management strategy is not clear.
The objective of this study was to assess the effect of a structured 8-wk exercise training program on insulin resistance and changes in body composition in obese children.
The study was 8 wk of structured supervised exercise intervention with outcome measures before and after the exercise period.
Fourteen obese children (12.70 +/- 2.32 yr; eight male, six female) with high fasting insulin levels were enrolled into the study. Intervention: Intervention consisted of 8 wk of supervised circuit-based exercise training, composed of three fully supervised 1-h sessions per week.
Outcome measures were assessed pretraining program and posttraining program and included insulin sensitivity (euglycemic-hyperinsulinemic clamp studies), fasting insulin and glucose levels, body composition using dual energy x-ray absorptiometry scan, lipid profile, and liver function tests.
Insulin sensitivity improved significantly after 8 wk of training (M(lbm) 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. Dual energy x-ray absorptiometry scans revealed no differences in lean body mass or abdominal fat mass.
An 8-wk 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.

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    • "Previously, Treuth et al. [46] have demonstrated that although modest changes were observed, a 5-month resistance training (3 times/week, 20 min/session, >50% of 1-repetition maximum) did not significantly alter fasting insulin (−4.1%) or fasting glucose levels (−4.0%) in obese girls aged 7–10 years (Table 3). Conversely, using the clamp technique, Bell et al. [47] reported that an 8-week period of combined exercise training (3 times/week, 60 min/session) without weight loss was associated with a significant improvement in insulin sensitivity (22.2%), determined within 48 hours after the last training session in obese youth. The improvement in insulin sensitivity was correlated with the improved cardiorespiratory fitness levels but not with body composition changes, suggesting that fitness level is of importance to reduce or prevent insulin resistance in obese children and adolescents. "
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    ABSTRACT: Despite considerable efforts to tackle childhood obesity, it is recognized as one of the biggest health problems globally. Childhood obesity is a leading cause of many comorbid conditions such as metabolic syndrome and insulin resistance as well as type 2 diabetes. A strong body of evidence suggests that regular exercise without calorie restriction or weight loss is associated with reduced insulin resistance as well as improved insulin sensitivity in overweight and obese adults. However, despite the well-known benefits associated with regular exercise alone, the independent role of exercise training without calorie restriction on insulin resistance is still uncertain in youth. Some studies observed that both the aerobic and resistance type of exercise training without calorie restriction resulted in meaningful changes in insulin sensitivity, suggesting that exercise alone is an effective therapeutic strategy for reducing insulin resistance in overweight and obese youth. However, only few studies are available on the optimal dose of exercise training without calorie restriction or preferred exercise modality for reducing insulin resistance, which warrants further investigations in the pediatric population.
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    • "To date, we are aware of two studies [37,38] wherein the effect of combined resistance and aerobic exercise on insulin sensitivity was examined in obese youth. In a nonrandomized controlled trial, Bell et al. [37] examined the effects of circuit training (3 times/wk, 60 min/session) on insulin sensitivity using the hyperinsulinemic euglycemic clamp technique in a mixed sample of obese boys and girls (n=14). "
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    ABSTRACT: As with the dramatic increases in childhood obesity over the past decades, the incidence of type 2 diabetes has increased among children and adolescents in the United States. Insulin resistance is a common feature of childhood obesity and increases the risk of type 2 diabetes, metabolic syndrome, and atherogenic lipoprotein profile in obese youth. Although cross-sectional studies report beneficial effects of physical activity or cardiorespiratory fitness on insulin sensitivity, the role of regular exercise alone (e.g., no calorie restriction) as a strategy to reduce the risk of type 2 diabetes is unclear in obese children and adolescents. In this mini review, we examined the independent effects of various exercise on glucose tolerance and insulin sensitivity in obese youth.
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    • "In the present study, we have observed a possible beneficial decrease in insulin, and similarly with previous observations, with positive changes in body size. However, some studies have evidenced that exercise alone can have a positive impact on insulin resistance risk in obese youth, without changes in body composition [42], probably exercise-induced improvements in insulin metabolism [43]. Exercise-related increases in insulin action is a result of several adaptative mechanisms in muscular, adipose, liver and endothelial tissues [44]. "
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    ABSTRACT: Multidisciplinary intervention is an alternative for the treatment of children and adolescent obese. However, the influence of age and menarcheal status in the pattern of metabolic response of obese girls has not been investigated. The following study examined the effects of a 12-week multidisciplinary intervention on metabolic health in overweight girls and the contribution of age and menarcheal status on the resulting changes. Eighty-eight overweight girls (10 - 16 years) were considered initially for this study and randomly assigned (intervention group: n = 58; control group: n = 30). Forty-six girls completed the intervention program and 16 girls completed the follow-up for the control group. The 12-week intervention included aerobic exercises (three times per week) and nutritional intervention. Anthropometrical measures (body mass, body mass index and waist circumference), menarcheal status and metabolic profiles including glucose, insulin, triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) were assessed in the beginning and after of intervention. Additionally, were calculated homeostatic model assessment-insulin resistance (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI). After 12-week, girls decreased significantly the body mass (76.6 ± 14.7 to 75.7 ± 14.6 kg) body mass index (30.1 ± 4.0 to 29.4 ± 4.0 kg/m2) and waist circumference (98.9 ± 10.9 to 96.5 ± 11.4 cm). There were differences in HDL-C (43.1 ± 8.2 to 50.3 ± 9.4 mg/dl), TG (120.9 ± 64.3 to 93.3 ± 47.9 mg/dl) and insulin (16.9 ± 7.6 to 15.6 ± 9.8 mg/dl). Relative contribution of age was significant only for within-subject variability in waist circumference. The multidisciplinary based on aerobic training intervention used in this study produced substantial benefits on metabolic health indicators in overweight girls. The changes observed were not related to inter-individual variability in age and maturity status.
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