Exercise and Insulin Resistance in Youth: A Meta-Analysis

Abstract

BACKGROUND AND OBJECTIVES: The prevalence of obesity and diabetes is increasing among children, adolescents, and adults. Although estimates of the efficacy of exercise training on fasting insulin and insulin resistance have been provided, for adults similar estimates have not been provided for youth. This systematic review and meta-analysis provides a quantitative estimate of the effectiveness of exercise training on fasting insulin and insulin resistance in children and adolescents.METHODS: Potential sources were limited to peer-reviewed articles published before June 25, 2013, and gathered from the PubMed, SPORTDiscus, Physical Education Index, and Web of Science online databases. Analysis was limited to randomized controlled trials by using combinations of the terms adolescent, child, pediatric, youth, exercise training, physical activity, diabetes, insulin, randomized trial, and randomized controlled trial. The authors assessed 546 sources, of which 4.4% (24 studies) were eligible for inclusion. Thirty-two effects were used to estimate the effect of exercise training on fasting insulin, with 15 effects measuring the effect on insulin resistance. Estimated effects were independently calculated by multiple authors, and conflicts were resolved before calculating the overall effect. RESULTS:Based on the cumulative results from these studies, a small to moderate effect was found for exercise training on fasting insulin and improving insulin resistance in youth (Hedges' d effect size = 0.48 [95% confidence interval: 0.22-0.74], P , .001 and 0.31 [95% confidence interval: 0.06-0.56], P , .05, respectively). CONCLUSIONS:These results support the use of exercise training in the prevention and treatment of type 2 diabetes. Pediatrics 2014;133:e163-e174 Mr Fedewa conceptualized and designed the study, conducted the initial analysis, and drafted the initial manuscript; Dr Gist coded and analyzed effects and reviewed and revised the initial manuscript; Dr Evans assisted with conceptualizing and designing the study and reviewed and revised the initial manuscript; Dr Dishman assisted with conceptualizing and designing the study, performed additional statistical analysis, and critically reviewed and revised the initial manuscript; and all authors approved the final manuscript as submitted. The global prevalence of pediatric type 2 diabetes mellitus (T2DM) has paralleled the rise in obesity, increasing steadily since the late 1970s. 1 This endocrine disorder is caused by a combination of peripheral insulin resistance (IR) in muscle and adipose tissue and inadequate insulin secretion from the pancreas, eventually resulting in a relative insulin deficiency. 2 Early dysfunction in b-cell activity and cellular IR appear long before manifestation of the signs and symptoms of T2DM. 3 Deterioration of peripheral insulin sensitivity and b-cell dysfunction can be observed as the disease progresses in youth at risk for developing metabolic syndrome and T2DM. 4 Puberty is marked by a decrease in physical activity 5 and an incr...

Physical activity attenuates the mid-adolescent peak in insulin resistance but by late adolescence the effect is lost: a longitudinal study with annual measures from 9–16 years (EarlyBird 66)

“…Unfortunately, the authors did not report age-specific associations, so it was unclear whether the strength of the association changed across the age range. A recent review of exercise-training trials did show that the impact on IR was slightly lower (though the difference was not statistically significant) at the later stages of puberty [9].…”

“…However, other reviews have shown that activity interventions (especially those of at least moderateintensity activity) consistently reduce IR and improve metabolic health, even when body fat is unchanged [8,9]. Together, these findings suggest that physical activity might improve IR and metabolic health via two mechanisms-one through the lowering of body fat, one independent of body fat.…”

ENDOCRINOLOGY AND ADOLESCENCE: Aerobic exercise reduces insulin resistance markers in obese youth: a meta-analysis of randomized controlled trials

“…In addition, two recent qualitative reviews have highlighted the influence of exercise on improving both adiposity and cardiometabolic risk (8,9), but both of them concluded that the role of physical activity alone in reducing the risk of type 2 diabetes and insulin resistance remained unclear. However, a recent meta-analysis has found a smallto-moderate improvement in fasting insulin levels and insulin resistance in children and adolescents with exercise training (10).…”

Insulin and BMI as Predictors of Adult Type 2 Diabetes Mellitus

“…[29][30][31] This is despite a lack of longitudinal data linking childhood insulin levels with later T2DM. 18 In this study we investigated the association between fasting insulin levels in childhood and later T2DM, alongside measures of BMI in childhood, in a longitudinal cohort of Finnish individuals.…”