Autonomic Cardiac Regulation in Response to Exercise and Molecular Hydrogen Administration in Well-Trained Athletes

Exercise induces considerable changes in the autonomic nervous system (ANS). The main objective of this chapter was to determine whether H2 administration through the hydrogen rich water (HRW) can affect ANS activity during two experimental exercise protocols in well-trained athletes. Both experiments were designed as randomized, double-blind, placebo-controlled crossover trials. Study A (12 fin-swimmers) assessed ANS responses before and during a simulated competitive day, and Study B (12 soccer players) assessed heart rate (HR) responses following a repeated sprint ability protocol (15 × 30 m). The heart rate variability method was performed to determine ANS activity for 5 min in standing and supine position using the DiANS PF8 system, and HR recovery was evaluated using the HR monitor at 1 and 3 min post exercise. Study A showed that three days of HRW administration induced a significant decline in vagal activity and HR stimulation in elite fin-swimmers solely in the standing position during the pre-competition phase of the simulated competition day. Study B showed that acute HRW administration can improve HR recovery of team sport athletes performing maximal repeated sprints that may translate to improved performance during training and competition. Therefore, it appears that H2 may be considered a promising dietary supplement in the future.