Longitudinal study of ontogenetic allometry of oxygen uptake in boys and girls grouped by maturity status.

The utility of removing the confounding effect of body mass on oxygen uptake by simply dividing the measured values by mass has been questioned: Allometric transformation or calculation of covariance analysis have been proposed as more appropriate alternatives. This study hypothesized that scaling factors for individual youths differ with maturity status. Peak oxygen uptake (peak VO2) during exercise on a bicycle ergometer, stature and body mass were measured at annual intervals in 47 active boys and 31 active girls from 11 to 14 years of age. All subjects attended sport schools during the study. The children were classified into two maturity categories, early and average (for the sake of sample size and consistency between sexes), and late on the basis of individual stature velocities in boys and age at menarche in girls. Individual data for peak VO2 were normalized for differences in body mass by double logarithmic transformation and regression analysis (ontogenetic allometry). Individual allometric coefficients (mean +/- SD) for boys showing a good fit were, respectively, 0.799 +/- 0.239 and 0.536 +/- 0.141 in early and average maturing boys combined and in late maturing boys. Logarithmic transforms of VO2 and mass were highly related (r > 0.90) in 10 of 16 early and average maturers, and in 18 of 31 late maturers. Corresponding individual allometric coefficients in girls were more variable, and the logarithmic transforms of VO2 and mass were not highly related (r < 0.70). Similar results were obtained for the relationships between the logarithmic transforms of VO2 and stature. The evidence thus suggests that in boys scaling VO2 for body mass varies with maturity status of the individual, and that there is considerable inter-individual variation in scaling coefficients during early and mid-adolescence. The increase in peak VO2 in active girls 11-14 years is not related to the increase in body mass or stature in the majority.