Influences of baseline heart rate variability on repeated sprint performance in young soccer players

AIM: The aim of this study was to assess the influence of the autonomic system on the performance of repeated sprints, involving predominantly neuromuscular power, in young soccer players. METHODS: Twelve young soccer players, selected for the Sicilian Regional Football Representative, mean age 15 years, were recruited. Baseline heart rate variability (HRV) was measured and indices of power spectral analysis (LF, HF, and ratio LF/HF) were calculated to evaluate the sympathovagal balance. The athletes performed 10 maximal 6--sec cycling sprints (RS), interspersed with 30--sec of recovery, to measure the peak power output (PP) represented by the highest power value recorded during a 6--sec sprint, and the mean peak power output (MPP) represented by the average of all highest power values recorded within a repeated--sprint bout. RESULTS: PP was negatively correlated with LF (r = --0.685, P = 0.0141) and LF/HF (r = --0.709, P =0.0098), and positively correlated with HF (r = 0.684, P = 0.0142). MPP was negatively correlated with LF (r = --0.610, P = 0.0350) and LF/HF (r = --0.606, P = 0.0366), and positively correlated with HF (r = 0.731, P = 0.0070). CONCLUSIONS: Our study shows that a baseline parasympathetic predominance in the ANS balance is associated with a better neuromuscular contribution to performance, resulting in higher values of PP and MPP during brief repeated maximal cycling sprints. The assessment of baseline HRV before exercise may be useful to monitor the physical condition of young soccer players and their readiness status to a higher performance