The effect of hydrotherapy recovery on central fatigue: A preliminary examination using transcranial magnetic stimulation

Insufficient recovery between successive bouts of exercise may lead to subsequent fatigue and consequently a reduction in athletic performance. Several post exercise recovery strategies, including various forms of hydrotherapy, have been implemented in an attempt to minimise the effects of fatigue. A limited but growing body of evidence supports the benefits of hydrotherapy, however, central nervous system (CNS) fatigue and hydrotherapy recovery has yet to be fully examined. The aim of this studywas to investigate the effectiveness of hydrotherapy recovery interventions on central fatigue following repeated cycling performance. Trained male recreational cyclists (8 m; 22–35 years of age) participated in a randomised cross-over design of three recovery interventions (coldwater immersion (CWI), contrastwater therapy (CWT), and passive rest) following exhaustive 30 min cycling exercise conducted over five days. CNS excitability was assessed using transcranial magnetic stimulation, cycling performance through a time to fatigue (TTF) test, blood markers for muscle inflammation and damage, and visual analogue scale for perception of fatigue. All conditions showed a progressive decline in TTF performance (from day 1 to day 5) with CWI and CWT showing significant decreases (p = 0.04) on days three (9.7 and 8.1% respectively), four (14.9 and 12.9% respectively), and five (17.7 and 13.5% respectively). However, for the passive recovery condition, a significant mean decrease (p = 0.04) in performance was observed from days 2 (13.2%) to 5 (30.8%). Similarly CNS excitability showed a progressive decline with CWI and CWT with an initial significant decrease of 10.2% and 11.8% respectively (p = 0.04). However, CNS excitability did not significantly change for either condition from days three to five (p = 0.14). CNS excitability for the passive recovery condition showed a significant decline ranging from 25.1% on day two to 30.5% on day five, when compared to day one (p = 0.04). Further, CNS excitability was associated with performance (r = 0.83) and perceptions of fatigue (r = 0.75).The results demonstrate that the hydrotherapies used in this study attenuated the decrement in cycling performance and CNS excitability and aided to minimise central fatigue, compared to the passive condition.