Validity Of Resting Heart-rate Variability To Predict VO2max In Professional Football Players

Abstract

Football involves a rapid sequence of sprinting and recovery and therefore a high level of aerobic fitness is necessary for optimal performance. Heart rate variability (HRV) analysis has been suggested as an alternative to exercise testing for predicting aerobic fitness. PURPOSE: To determine if resting HRV can be used to accurately predict VO2max in professional football players. METHODS: 36 NFL football players (age: 25.5 ± 2.3y, mass: 116.1 ± 25.3kg) underwent 5 minutes of ECG data collection while resting in a supine position. A specialized data acquisition system recorded R-R intervals and used proprietary equations to predict VO2max. Subjects then performed an incremental speed 20m shuttle run test while metabolic data were continuously collected and VO2maxwas measured using 5s averaging. Linear and quadratic curve estimation were then used to determine the relationship between HRV-predicted VO2max (dependent variable) and metabolically measured VO2max (independent variable). RESULTS: HRV-predicted VO2max was 52.35 ± 8.99 mL O2 · kg-1 · min-1. Measured VO2max was 51.40 ± 8.37 mL O2 · kg-1 · min-1. Linear regression revealed r = 0.556 (p < 0.001) and quadratic regression revealed r = 0.703 (p < 0.001). CONCLUSIONS: These data suggest that resting HRV has a moderate relationship to measured VO2max in professional football players. The relationship is best modeled as quadratic, such that football players with the lowest and highest HRV-predicted VO2max have the lowest measured VO2max. Discrepancies between measured and predicted VO2max may be a consequence of test effort or actual physiologic mechanisms. Either of these factors could potentially be related to playing position, though a small sample size precluded formal examination of this. These results suggest that HRV may be used to provide an estimate of VO2max in a group of professional football players, but is not likely accurate for predicting VO2max for a given individual player. Future research is necessary to determine the accuracy of HRV-prediction for other specific athletic populations and if protocols combining ECG and EEG measurements provide greater accuracy for predicting VO2max.