LAUSR

BACKGROUND Hydrogen gas (H2 ) has entered the world of experimental therapeutics approximately four and a half decades ago. Over the years, this simple molecule appears to drive more and more scientific attention perhaps due to a dualism of H2 affirmative features demonstrated in numerous in vitro, animal and human studies on one side, and stillpuzzling mechanism(s) of its biological activity on the other. Up to this point, H2 was scrutinized for more than 170 different disease models and pathologies, and many research groups across the world have lately started to dynamically investigate its conceivable performance-enhancing potential. METHODS We outlined here the studies indexed in leading research databases (PubMed, Web of Science, SCOPUS, JSTORE) that explored the effects of hydrogen on exercise performance, and also addressed important restraints, open questions, and windows of opportunities for forthcoming research and possible H2 enactment in exercise physiology. About two dozen trials have been identified in this domain, with most published during the past 5 years, while drinking hydrogen-rich water recognized as the most convenient method to deliver H2 in both animal and human studies. RESULTS Either administered as an inhalational gas, enteral hydrogen-rich water, or intravenous hydrogen-rich saline, H2 seems to favorably affect various exercise performance outcomes and biomarkers of exercise-associated fatigue, inflammation, and oxidative stress. Not all studies have shown corroborative effects, and it appears that the gold-standard protocol for applying H2 in the field of exercise science does not exist at the moment, with studies markedly differ in the dose of H2 administered, the duration of a treatment, and the source of hydrogen. CONCLUSION H2 is a newfangled and rather effective performance-enhancing agent yet its promising ergogenic potency has to be further validated and characterized in more well-controlled, appropriately sampled and long-term mechanistic trials. Also, appropriate regulation of hydrogen utilization in sport as an exotic medical gas may require distinctive legislative actions of relevant regulatory agencies in the future.