Short term power output in relation to growth and maturation

Objective-To examine short term power output during growth and maturation u sing a multilevel modelling approach. Methods-Body mass, stature, and triceps and subscapular skinfold thicknesse s of boys and girls, aged 12.2 (0.4) years (mean (SD)) at the onset of the study, were measured at age 12, 13, and 17 years. Sexual maturation, classi fied according to Tanner's stage of pubic hair development, was assessed on the first two occasions and assumed to be stage 5 at: 17 years. Peak power (PP) and mean power (MP) were assessed on each occasion using the Wingate anaerobic test. Results-Initial models, founded on 417 determinations of short term power o utput, identified body mass, stature, and age as significant explanatory va riables of both PP and MP. The values for girls were significantly lower th an those for boys, and a significant age by sex interaction described a pro gressive divergence in the MF of boys and girls. The introduction of sum of two skinfold thicknesses produced a model with an improvement in fit as in dicated by a significant change in log likelihood. The stature term was neg ated and the body mass term increased. The age and sex terms were reduced b ut remained significant. The age by sex interaction term remained a signifi cant explanatory variable for MP. Maturity effects were non-significant add itional explanatory variables in all models of power output. Conclusion-The values of PP and MP for boys are higher than those for girls , and, for MP, sex differences increase with age. Body mass and skinfold th icknesses are significant influences on both PP and MP, but age exerts a po sitive but non-linear effect on power output independent of body size and f atness.