Cardiac response to progressive cycle exercise in moderately obese adolescent females

Purpose: To assess cardiac responses to exercise and cardiac functional capacity in moderately obese adolescent females. Methods: Thirteen healthy females (mean age 13.6 ± 1.5 years) with a body mass index from 30 to 43 kg per m² underwent maximal cycle testing. Cardiac responses were measured by Doppler echocardiogram, and gas exchange variables were determined with open circuit spirometry. Data were analyzed by independent Student's t-tests. Results: Peak oxygen uptake relative to height^3.0 was significantly greater in the obese (570 ± 90 ml m^-3) compared to the nonobese controls (485 ± 60 ml m^-3). This difference was explained by a higher peak cardiac output (4.50 ± 1.06 L m^-3 vs. 3.81 ± 58 L m^-3) and stroke volume (24 ± 5 ml m^-3 vs. 19 ± 3 ml m^-3) in the obese. Maximal cardiac index was similar in the two groups. There was no evidence of myocardial dysfunction during exercise in either group. Conclusions: Low aerobic fitness in obese adolescents as indicated by depressed peak VO₂ per kg body mass and limited endurance performance does not reflect decreased cardiac functional capacity.