Allometric Scaling Is The Best Method For Normalizing Maximal Oxygen Uptake In Young Soccer Players

Abstract

Maximum oxygen uptake (VO2max) has been considered an important marker of health and sports performance. Traditionally VO2max is normalized by body mass (mL.kg-1.min-1), however this approach leads an overestimation of the performance in lighter individuals and an underestimation in those heavier. Determine what method is the most appropriate to normalize VO2max is important to allow comparisons between individuals with different body size. PURPOSE: To investigate the best method of normalization for VO2max in young athletes heterogeneous in body size using separate scaling variables and allometric modeling. METHODS: Seventy-nine young soccer players (age = 15.3±1.5 years, body mass = 68±10 kg, height = 175±8 cm and VO2max = 4136±552 mL.min-1) participated in this study. Scaling variables were body mass, height, body mass index (BMI), interaction between body mass height, body surface area (BSA), rectus femoris cross-section area (CSA), thigh and leg muscle thickness (MT) and muscle volumes (MV) (thigh, leg, and lower limbs). Allometric model was adopted to examine the relationship between body size descriptor and VO2max (Y = aXbε). CSA, MT and MV were measured using ultrasonography and VO2max using a metabolic cart. The variables with a very large correlation with VO2max were considered for normalization. RESULTS: CSA, BMI and thigh and leg MT and MV were discarded as a moderate to large correlation with VO2max mL.min-1 (0.3 < r < 0.7) was found. Body mass, height, BSA, interaction body mass height, and lower limb MV showed a very large correlation (r > 0.7) with VO2max mL.min-1. After normalization by body mass (mL.kg-1.min-1), height (mL.m-1.min-1), BSA (mL.m-2.min-1), lower limbs MV (mL.mL-1.min-1) and interaction body mass height (mL.kgm-1.min-1) a significant correlation among scaling variables and normalized VO2max remained (0.3 < r < 0.8, p<0.05). The allometric scaling of body mass (mL.kg-0.79.min-1), height (mL.m-2.18.min-1), BSA (mL.m-2.37.min-1), lower limbs MV (mL.mL-0.43.min-1) and interaction body mass height (mL.kgm-0.63.min-1) were effective to adjust the effect of body size on VO2max, with no significant correlation among scaling variables and normalized VO2max (p>0.05). CONCLUSION: Allometric scaling is best method to normalize VO2max in young soccer players.