Autonomic modulations of heart rate variability and performances in short-distance elite swimmers

Purpose: Endurance exercise is associated with high cardiac vagal tone, but how the cardiac autonomic control correlates with shorter anaerobic performances is unknown. Therefore, the aim of this study was to evaluate how autonomic modulations of heart rate (HR) variability (V) correlate with performances of short- (OBLA) were calculated. Results and conclusion: Vagal indices were highest in the morning where they positively correlated with very short-distance times (higher the index, worse is the 50-m performance). Sympatho/vagal indices were highest after training where they negatively correlated with short-distance times (higher the index, better is the 100-m performance). V_OBLA did not correlate with the performances. Therefore, autonomic HRV indices and not V_OBLA predict short and very short, most anaerobic, performances. Results also suggest that a strong cardiac vagal control has no effect on short performances and is even detrimental to very short performances, and that the capacity to powerfully increase the sympathetic tone during exercise may improve short, but not very short performances.