Exercise performance and magnetic resonance imaging-determined thigh muscle volume in children

This study examined the relationships between thigh muscle volume (TMV) and aerobic and anaerobic performance in children. A total of 32 children, 16 boys and 16 girls, aged 9.9 (0.3) years completed a treadmill running test to exhaustion for the determination of peak oxygen uptake (peak VO2) and a Wingate Anaerobic Test (WAnT) for the determination of peak power (PP) and mean power (MP). The volume of the right thigh muscle was determined using magnetic resonance imaging. TMV was not significantly different in boys and girls [2.39 (0.29) l vs 2.18 (0.38) l, P > 0.05]. Peak VO2 and MP were significantly higher in boys than girls (P < 0.01) whether expressed in absolute, mass-related or allometrically scaled terms. Absolute PP was not significantly different in boys and girls but mass-related and allometrically scaled values were higher in boys (P < 0.01). TMV was correlated with absolute peak VO2, PP and MP in both sexes (r = 0.52-0.89, P < 0.01). In boys, mass-related PP was correlated with TMV (r = 0.53, P < 0.01), and in girls mass-related peak VO2 was correlated with TMV (r = -0.61, P < 0.01). However, in neither sex were allometrically scaled peak VO2, PP or MP correlated with TMV (P > 0.05). There were no significant differences between boys and girls in terms of peak VO2, PP or MP when expressed in a ratio to TMV or allometrically scaled TMV. In conclusion, this study has demonstrated that, when body size is appropriately accounted for using allometric scaling, TMV is unrelated to indices of aerobic and anaerobic power in 10-year-old children. Furthermore, there appear to be no qualitative differences in the muscle function of boys and girls in respect of aerobic and anaerobic function.