Effects of Exercise Modality on Insulin Resistance and Ectopic Fat in Adolescents with Overweight and Obesity: A Randomized Clinical Trial

Abstract

Objective: To examine whether a combined aerobic exercise and resistance exercise is more effective than either aerobic exercise or resistance exercise alone in improving insulin sensitivity and reducing total adiposity and ectopic fat in adolescents.

Study design: A total of 118 sedentary adolescents with overweight/obesity (body mass index >85th percentile, 12-17 years) were recruited from October 2013 through April 2017 at Children's Hospital of Pittsburgh. Participants were randomized to 1 of the following 6-month exercise groups (3 d/wk, 180 min/wk): aerobic exercise (n = 38), resistance exercise (n = 40), and combined aerobic exercise and resistance exercise (n = 40). The primary outcome was the change in insulin-stimulated glucose disposal by a 3-hour hyperinsulinemic-euglycemic clamp. The secondary outcomes were changes in liver fat by proton magnetic resonance spectroscopy and intermuscular adipose tissue by computed tomography.

Results: Of the 118 participants randomized, 85 participants (72%) completed the study with 90% exercise attendance. Total adiposity reduced similarly in all groups (-2%, P < .05). After adjusting for age and sex, insulin-stimulated glucose disposal increased (P < .05) in all groups, with the increase in the aerobic exercise group being greater than the resistance exercise group (1.7 ± 0.1 vs 0.7 ± 0.1 mg/kg/min, P < .05) but not different from the combined group (1.2 ± 0.1 mg/kg/min). Liver fat was reduced (P < .05) in the aerobic exercise (-0.6%) and combined (-0.6%) groups but not in the resistance exercise group (-0.3%, P > .05). Intermuscular adipose tissue decreased (P < .05) similarly in all groups.

Conclusion: Combined aerobic exercise and resistance exercise and aerobic exercise alone are similarly beneficial in improving insulin sensitivity and reducing ectopic fat in adolescents with obesity.

Trial registration: ClinicalTrials.gov: NCT01938950.

Keywords: childhood obesity; exercise; insulin sensitivity; intermuscular fat; liver fat.

Copyright © 2018 Elsevier Inc. All rights reserved.

Figures

FIGURE 1.

Participant flow diagram. All subjects assigned to each treatment (including those who discontinued the study) were included in intent-to-treat analyses.

FIGURE 2.

A. Improvements in insulin-stimulated glucose disposal within group. Data are shown as predicted means and standard errors (SE) of differences in pre-intervention versus post-intervention values adjusting for age and sex. * Significant pre-intervention versus post-intervention differences within group, P<0.05. † Significant pre-intervention versus post-intervention differences compared with the resistance group, P<0.05. B. Reductions in 2-hr glucose level during a 2-hr oral glucose tolerance test within group. Data are shown as predicted means and standard errors (SE) of differences in pre-intervention versus post-intervention values adjusting for age and sex. * Significant pre-intervention versus post-intervention differences within group, P<0.05.