The effects of hormone changes over the menstrual cycle on elite athlete performance: meta-analysis and suggested standardised protocol.

Abstract

Abstract: Fluctuations in endogenous sex hormones across the menstrual cycle (MC) have been hypothesised to have physiological changes that could influence athletic performance. Due to the marginal nature of elite sport, even subtle physiological changes can meaningfully influence performance outcomes in elite female athletes. This systematic review and meta-analysis evaluated the effects of the menstrual cycle phase (MCP) on maximal oxygen uptake (VO2 max) in elite female athletes. Bibliographic databases were searched for studies that confirmed the MCP through serum or plasma hormone analysis and that involved elite or well-trained athletes. Meta-analyses compared VO2 max between early follicular (EF) and mid-luteal (ML) phases. Across five studies, no statistically significant differences were found in VO2 max between phases, although small, non-significant decreases in performance were observed in the EF phase. Despite null results, biological plausibility and athlete-reported experiences suggest that minor or individual-specific effects of MCP on performance may exist. Future research should use standardised protocols, larger cohorts and individualised sport-specific outcomes to better understand how MC dynamics influence an elite female athlete's performance. A suggested standardised protocol for conducting future research in this area was developed.

Lay summary: Elite female athletes train and compete at the highest levels of sport, where even small changes in performance can make a difference between winning and losing. One possible under-researched influence on performance is the menstrual cycle (MC). During this monthly cycle, there are natural changes in hormone levels. We looked at all the published research to explore whether different MC stages affect sports performance in elite female athletes. No substantial evidence was found that endurance changes significantly across the cycle. However, a slight trend showed that performance might be negatively impacted during menstruation, when hormone levels are low. While these results suggest that the MC might not have a major impact overall, small changes could still matter in elite sport. More research with larger groups and better testing methods is needed to fully understand how the MC might affect an individual athlete's performance.