Prediction Of VO2 Peak Relative To Fat-free Mass In Adolescents

Abstract

VO2Peak is typically expressed relative to total body mass. The unit of expression for VO2Peak (mL/kg/min) is used for assessment in clinical, athletic, and physical education settings. However, expression of VO2Peak relative to fat-free mass (FFM) provides a more accurate assessment of cardiorespiratory function independent of fat mass (FM). PURPOSE: The purpose of this study was to develop prediction models to estimate VO2Peak relative to FFM (mL/kg FFM/min) from both the one-mile run/walk (1MRW) and the Progressive Aerobic Cardiovascular Endurance Run (PACER) in adolescents. METHODS: The sample consisted of 90 adolescents (38 girls, 52 boys; Mean Age = 14.7 ± 1.3 years) recruited from local middle and high schools. Each student completed the 1MRW and PACER, in addition to a maximal treadmill VO2Peak test. FFM was obtained by subtracting FM from total body mass. FM was estimated using percent body fat (%BF) computed using the Slaughter et al. equation via two-site skinfold thickness. Multiple linear and polynomial regressions were used to develop two separate models using 1MRW or PACER to predict VO2Peak (mL/kg FFM/min). Additional predictors examined included Height, Age, Sex, and an Age x Sex interaction term. RESULTS: The developed 1MRW model was VO2Peak (mL/kg FFM/min) = (−14.15 × 1MRW time) + (0.66 × 1MRW time)2 + 125.60 (R = 0.59, R2 = 0.34, SEE = 7.14 mL/kg FFM/min), and the PACER model was VO2Peak (mL/kg FFM/min) = (0.19 × PACER laps) + 45.98 (R = 0.56, R2 = 0.32, SEE = 7.24 mL/kg FFM/min). No other predictor variable entered into the models significantly increased the predictive accuracy. When VO2Peak was expressed relative to total body mass (ml/kg/min) the predictive accuracy increased for both the 1MRW (R = 0.83, R2 = 0.68, SEE = 4.69 mL/kg/min) and PACER (R = 0.79, R2 = 0.64, SEE = 4.98 mL/kg/min) models. CONCLUSION: Both the 1MRW and PACER aerobic capacity prediction models were able to explain approximately one-third of the variance in measured VO2Peak when expressed relative to FFM. Since physical performance is biased toward total body mass and the measurement of FFM using two-site skinfold thickness may have large measurement error, use of the traditional expression of VO2Peak relative to total body mass was more strongly associated with 1MRW and PACER performance than VO2 Peak relative to FFM.