LONGITUDINAL ANALYSIS OF SCALING VO2 FOR DIFFERENCES IN BODY-SIZE DURING PUBERTY - THE MUSCATINE STUDY

Purpose: The purpose of this study was to determine an appropriate met hod to ''normalize'' oxygen uptake (V) over dot O-2) for body size in children and adolescents. Methods: We examined allometric scaling fact ors for a cohort of 126 children (mean age at baseline = 10.3 yr) part icipating in a 5-yr follow-up study. Each year for 5 yr we measured pe ak (V) over dot O-2, submaximal (V) over dot O-2, body mass, height, b ody composition, and sexual maturation. We sorted the 5-yr data set by si sui maturation and gender and then used the generalized estimating equation method to estimate regression parameters that described the influence of log transformed body mass on log transformed (V) over dot O-2. All analyses were repeated using log transformed far-free body m ass (FFM) in lieu of icg transformed body mass. Results: Models using FFM appeared better at eliminating the effect of body size on (V) over dot O-2. In bays a univariate model with a FFM exponent of 0.91 and i n girls a univariate model with a FFM exponent of 0.87 satisfactorily normalized peak (V) over dot O-2 However we could not identify a commo n body size exponent for both boys and girls. Conclusions: Results sup port the use of allometric scaling of (V) over dot O-2 as a function o f FFM for maturing boys and girls but indicate that the effects of mat uration on the relationship between (V) over dot O-2 and body size dif fer between boys and girls.