Kelly, A. S., Wetzsteon, R. J., Kaiser, D. R., Steinberger, J., Bank, A. J., & Dengel, D. R. (2004).Journal of Pediatrics, 145,731-736.
Sedentary behavior has been suggested as a major factor linking obesity and several comorbidities, including inflammation, insulin resistance, and endothelial dysfunction. Studies of aerobic exercise training have consistently demonstrated improvements in endothelial function. Based on these findings from studies of adults, this study examined the associations of subclinical inflammation, fasting insulin levels (as a marker for insulin resistance), and endothelial function in overweight children and adolescents before and after aerobic exercise. The baseline sample included 25 healthy, overweight children and adolescents (body mass index [BMI] >85th age- and sex-specific percentile). Standardized protocols were used for assessment of vascular (endothelial) function, laboratory measures (C-reactive protein [CRP], insulin, lipid levels, glucose) and body composition, aerobic fitness, and blood pressure at baseline and 8 weeks postintervention. Twenty participants (mean age 11 +/- 0.63 years) were randomly assigned to supervised (stationary cycling) exercise training (four sessions per week at 50% to 60% VO2 peak for 30 minutes, progressing to 70% to 80% VO2 peak for 50 minutes) or to the control group (maintenance of regular patterns of physical activity). A baseline association was observed between CRP and fasting insulin (r = 0.62; p <.001), which remained significant (r = 0.52; p <.05) after adjustment for percent body fat, lipids, fasting glucose, and systolic and diastolic blood pressure. After 8 weeks, significant improvements in fitness (VO2), high-density lipoprotein (HDL) cholesterol, and endothelial function were observed in the exercise group compared with the control group.
The results of this study are consistent with prior research in adults and suggest that early in life, inflammation is associated with fasting insulin levels in overweight individuals and may be involved in the pathogenesis of insulin resistance. This hypothesis awaits confirmation in future research with larger samples of overweight children and adolescents. The observed benefits of exercise on vascular function, cardioprotective HDL cholesterol, and fitness add to the existing evidence and provide nurses and child health professionals with additional rationale for encouraging physical activity and fitness early in life.
Comment by Laura L. Hayman