A two-year examination of the relation between internal and external load and heart rate variability in Australian Rules Football

Abstract

ABSTRACT The relationship between heart rate variability (HRV) and training load in team-sport is unknown. We therefore assessed relations between completed training-load in the previous 1-, 3- and 7-days and waking HRV in professional Australian Rules Football. Linear-mixed models analysed changes in HRV, considering training load from the previous 1-, 3- and 7-days. Total Distance (TD), distance >14.4 km ‧ h−1 (HSR) and >24.9 km ‧ h−1 (Sprint-Distance), duration >85% max heart rate and Rating of Perceived Exertion were included as independent variables. Sub-group analysis of season-phase and years of professional experience was also conducted. Increased three-day Sprint-Distance reduced HRV in the first 8-weeks of pre-season (−13.1 ms, p = 0.03) and across the data collection period (−3.75 ms, p = 0.01). In first-year players, higher previous-day (−63.3 ms, p=0.04) and seven-day TD (−38.2 ms, p = 0.02) reduced HRV, whilst higher seven-day HSR increased HRV (34.5 ms, p = 0.01). In players with five-to-seven years of professional experience, higher three-day (−14.4 ms, p = 0.02) and seven-day TD (−15.7 ms, p = 0.01) reduced HRV, while higher three-day HSR increased HRV (12.5 ms, p = 0.04). In players with greater than eight years of professional experience, higher previous-day Sprint-Distance reduced HRV (−13.1 ms, p < 0.008). Completed training load across the previous 7-days influences HRV, but the relation between variables is complex and influenced by professional experience and season-phase.