EFFECT OF MENTOR-LED VIGOROUS AEROBIC EXERCISE PROGRAM ON BODY COMPOSITION, PEAK VO2, AND INSULIN SENSITIVITY IN OVERWEIGHT AND OBESE ADOLESCENTS

In the past few decades obesity rates in the US have reached epidemic proportions in both adults and children. Nearly one-third of American adults are obese, and since 1980, the obesity rates for children 6-11 years and 12-19 have nearly tripled (Centers for Disease Control and Prevention, 2012). Obesity in adults and children is associated with abnormal lipid profiles, insulin resistance and low cardiorespiratory endurance (CRE). The link between disease risk and low CRE has been well established in adults and to a lesser extent in children and adolescents. The PURPOSE of this study was to evaluate the effect of a mentor-led vigorous aerobic exercise program on insulin resistance, body composition, and peak VO2 in overweight and obese adolescents. METHODS Subjects (n=23) for the study were randomly assigned to two groups. Eleven participants were assigned exercise mentors and exercised approximately three times per week for 45 to 60 minutes each session. An additional 12 adolescents were randomly assigned to a control group. Body composition, Peak VO2, and HOMA-IR levels were assessed at pre-, post-, and follow-up testing. A 2 (control vs. experimental) x 3 (pre-, post-, follow-up) repeated measures analyzes of variance (ANOVA) was used to analyze the data using the MANOVA procedure in JMP®. RESULTS No significant intervention effect was observed for body composition measures. Significant effects were observed in Peak VO2max (p = 0.0066) and total treadmill time (p = 0.0116). In the experimental group, effect size, measured by Cohen's d, showed a high effect size (d = 0.88) for Peak VO2max from pre to post test and a moderate decrease in effect size (d = -0.44) from post to follow-up. Similar findings were shown with total treadmill time with a small positive effect size from pre to post (d = 0.29) and a small decrease from post to follow-up (d = -0.33). No significant between group differences were found in HOMA-IR. However, the intervention group's HOMA-IR, improved between baseline and post testing period. The current findings show that independent of weight loss and change in body composition, positive changes in fitness were significantly different from the control group, and the fitness improvements were maintained throughout the duration of the study. Insulin resistance improved for the experimental group from baseline to post testing and was maintained over the 12 week non-intervention follow-up period. CONCLUSION A mentor-led exercise intervention does have potential to be effective at increasing health outcomes independent of weight loss, which can be sustainable after the cessation of the program