Oxygen uptakes adjusted for body composition in normal-weight and obese adolescents

Objective: To test whether resting oxygen uptake (VO2), submaxinial VO2, and maximal VO2 (VO2max) differs between obese adolescents (n = 18; BMI > 30) and a matched normal-weight control group after adjustment for differences in fat-free mass (FFM) and fat mass (FM). Research Methods and Procedures: FFM and FM were assessed by DXA. Resting VO2, submaximal VO2, and VO2max, were measured by indirect calorimetry. Results: There was no difference in resting VO2 between groups after adjusting for FFM and FM. Submaximal VO2 did not differ between groups after adjusting for body weight. Percentage VO2max and NET VO2 (VO2max - resting VO2) were significantly higher in the obese group during submaxinial exercise, however not after adjusting for body weight. VO2max was not significantly different between groups after adjusting for FFM. Discussion: When body compositions are appropriately controlled for, resting VO2 submaximal VO2, and VO2max do not differ between obese and normal-weight adolescents. These data suggested that the higher relative VO2 observed in obese adolescent subjects is due to their higher FM and not to an impaired VO2max even though they may be less physically active.