Effects of Melatonin Supplementation on Professional Football Player Performance: A Systematic Review

Background: to know the existing documentation related to exogenous melatonin in the performance of professional soccer players. Methods: critical and systematic review. Data were obtained by looking up the following bibliographic data bases: Web of Science, MEDLINE (via PubMed), Embase, Cochrane Library and Scopus. The used terms were "Soccer Athlete", "Melatonin" and "Soccer Performance", using as a filter: "Humans". The search update was in May 2023. Results: having applied the inclusion and exclusion criteria, 8 articles were selected out of 59 retrieved references. The dose of melatonin administered in the studies ranged between 5 and 8 mg. The outcomes showed a decrease in oxidative stress, muscle damage and inflammatory markers in the melatonin-treated group. Conclusions: Exogenously administered melatonin seems to attenuate some of the effects derived from physical exercise such as oxidative stress, inflammation and muscle damage in professional soccer players, and since it has no potential adverse effects, it could be interesting to apply it in this population. However, the direct effects of melatonin supplementation on physical performance have not been demonstrated, so more research is needed on the intervention period, effective dose and larger participant populations.