Peak power in obese and nonobese adolescents: effects of gender and braking force.

Abstract

The aim of this study was to determine the cycling peak power (CPP) of obese compared with nonobese adolescents and to identify possible effects of braking force (BF) and gender on CPP. To adjust for differences in body size, we used ratio standard and allometric model. Obese (26 girls, 18 boys) and nonobese (30 girls, 20 boys) adolescents participated. Fat-free mass (FFM) was determined by dual-energy x-ray absorptiometry (DEXA) in obese and by anthropometric method in nonobese groups. A force-velocity test was used to measure peak power (flywheel inertia included) for BF corresponding to applied load: 25, 50, and 75 g x kg(-1) body mass (BM). The highest peak power was defined as CPP. CPP was independent of BF in nonobese adolescents but dependent in obese adolescents. The optimal braking load is approximately 6.5% FFM. Absolute CPP was higher in obese than nonobese adolescents. Related to BM, CPP was significantly lower in obese than nonobese adolescents, using the standard ratio or the allometric model. These differences disappeared when CPP was related to FFM. Multiple stepwise regression showed that FFM was the most important explanatory variable of the variance of CPP (72%) in obese and nonobese adolescents. No significant difference between obese and nonobese adolescents occurred when Fopt was related to FFM (standard or power function ratios used). There was no gender effect on CPP, and the manner of expressing CPP did not affect the results. However, girls showed a higher FFM-related Fopt than boys, using standard and power function ratios. There was no significant difference between obese and nonobese girls and boys for anaerobic performance (CPP and Fopt) when FFM was taken into account.