Allometric modelling of peak oxygen uptake in male soccer players of 8-18 years of age

Background: Peak oxygen uptake (VO2peak) is routinely scaled as mL O-2 per kilogram body mass despite theoretical and statistical limitations of using ratios.Aim: To examine the contribution of maturity status and body size descriptors to ageassociated inter-individual variability in VO2peak and to present static allometric models to normalize VO2peak in male youth soccer players.Subjects and methods: Total body and estimates of total and regional lean mass were measured with dual energy X-ray absorptiometry in a cross-sectional sample of Portuguese male soccer players. The sample was divided into three age groups for analysis: 8-12 years, 13-15 years and 16-18 years. VO2peak was estimated using an incremental maximal exercise test on a motorized treadmill. Static allometric models were used to normalize VO2peak.Results: The independent variables with the best statistical fit explained 72% in the younger group (lean body mass: k = 1.07), 52% in mid-adolescent players (lean body mass: k = 0.93) and 31% in the older group (body mass: k = 0.51) of variance in VO2peak. The inclusion of the exponential term pubertal status marginally increased the explained variance in VO2peak (adjusted R-2 = 36-75%) and provided statistical adjustments to the size descriptors coefficients.Conclusion: The allometric coefficients and exponents evidenced the varying inter-relationship among size descriptors and maturity status with aerobic fitness from early to late-adolescence. Lean body mass, lean lower limbs mass and body mass combined with pubertal status explain most of the inter-individual variability in VO2peak among youth soccer players.