Effects on Resting Energy Expenditure, Aerobic and Musculoskeletal Fitness: The HEARTY Exercise Trial

Abstract

There is a need to test the effectiveness of lifestyle interventions to combat the epidemic of obesity in adolescents. We examined the effects of aerobic exercise, resistance exercise and their combination on resting energy expenditure (REE), aerobic and musculoskeletal fitness in obese adolescents in a randomized trial. Participants were inactive, overweight or obese adolescents (n=304) aged 14-18 yr who volunteered for the HEARTY (Healthy Eating Aerobic and Resistance Training in Youth) trial. After a 4-week diet and exercise run-in, participants were randomized into 4 groups for 22 weeks: diet + aerobic exercise (A), diet + resistance exercise (R), diet + aerobic + resistance exercise (A+R), or diet-only control (C). All tests were conducted at baseline and after 6 months. REE and aerobic fitness (VO2peak) were tested using indirect calorimetry at rest and during a maximal treadmill test respectively. Musculoskeletal fitness was assessed using CSEP-CPAFLA protocols for grip strength, push-up, sit & reach, curl-up and vertical jump tests. VO2peak increased significantly in A (30.6 ± 0.6 to 33.4 ± 0.7 mlO2/kg/min, p=0.002 vs. C and p=0.026 vs. R) and nonsignificantly in A+R (30.6 ± 0.6 to 32.2 ± 0.6 mlO2/kg/min, p=0.076 vs. C). There were significant (p<0.05) within-group improvements in maximal treadmill workload and abdominal curl-ups in all 3 exercise groups but not in C. Changes in REE did not differ among groups. Only aerobic training increased peak oxygen consumption. Aerobic, resistance or combined exercise increased abdominal muscular endurance but not resting energy expenditure in obese adolescents.