Predicting v o max from Treadmill Performance in American-Style Football Athletes

Crouse, SF, Tolson, H, Lytle, J, Johnson, KA, Martin, SE, Green, JS, Oliver, J, Carbuhn, A, Lambert, B, and Bramhall, JP. Predicting Vomax from treadmill performance in American-style football athletes. J Strength Cond Res 33(4): 1028-1034, 2019 - Prediction equations are often used to estimate Vomax in the general population but are lacking for American-style football (ASF) athletes. We sought to develop a regression model to estimate Vomax from treadmill exercise time in ASF athletes and compare our football Vomax model with 2 published prediction equations (Foster et al., 1984, and Bruce, 1973). American-style football athletes (N = 472, age = 18 ± 1 year, height = 186.1 ± 8.2 cm, and body mass = 101.8 ± 20.4 kg) underwent treadmill exercise to voluntary exhaustion (Bruce protocol). Maximal exercise time was recorded in minutes (Tmin), and Vomax was simultaneously measured (M-Vomax, mlO·kg^-1·min^-1) by an automated gas-analysis system. Athletes were then randomly divided into validation and cross-validation groups (n = 236). Linear regression yielded estimates of Vomax from Tmin as follows: validation Vomax = 4.012 × Tmin - 4.628 (r² = 0.678, p < 0.001, and SEE = 4.07); cross-validation Vomax = 4.025 × Tmin - 4.693 (r² = 0.661, p < 0.001, and SEE = -4.16). These equations had a cross-validation coefficient of 0.813 and a double cross-validation coefficient of 0.823. Differences between the slopes of the 2 equations were not significant (t-test, p = 0.9603). Because validation and cross-validation groups were not statistically different on any variables measured (multivariate analysis of variance, p > 0.05), all athletes were combined to yield our final prediction equation: football Vomax = 4.017 × Tmin - 4.644 (r² = 0.670, p < 0.001, and SEE = 4.11). Repeated-measures analysis of variance demonstrated significant differences (p < 0.001) in estimates of Vomax among Foster (44.1 ± 6.1), Bruce (47.1 ± 5.5), and our football (45.1 ± 5.8) equations. Foster and Bruce Vomax estimates were also significantly different from M-Vomax (diff = -0.975 and 1.995, respectively, p < 0.001). Vomax of ASF athletes can be reasonably estimated by our football prediction equation using maximal treadmill time as the predictor.