RESUMO
BACKGROUND: 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 LF/HF ratio) were calculated to evaluate the sympathovagal balance. The athletes performed 10 maximal 6-second cycling sprints (RS), interspersed with 30 seconds of recovery, to measure the peak power output (PP) represented by the highest power value recorded during a 6-second 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 (ρ=-0.685, P=0.0141) and LF/HF (ρ=-0.709, P=0.0098), and positively correlated with HF (ρ=0.684, P=0.0142). MPP was negatively correlated with LF (ρ=-0.610, P=0.0350) and LF/HF (ρ=-0.606, P=0.0366), and positively correlated with HF (ρ=0.731, P=0.0070). CONCLUSIONS: Our study shows that a baseline parasympathetic predominance in the autonomic nervous system 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 for to monitor the physical condition of young soccer players and their readiness status to a higher performance.
