Uncovering a hidden modulator for women in sports: An exploratory study of menstrual pain and brain connectivity

BackgroundThe menstrual cycle (MC), the use of combined oral contraceptives (COCs), and the presence of menstrual pain have long been overlooked factors in female athletes' health. The influence of hormonal fluctuations and pain may not only alter perceived performance and trainability but could also induce changes in brain network connectivity.ObjectivesThis study aimed to investigate whether resting-state functional connectivity (rsFC) differs between phases across the MC and COC cycle, as well as between naturally cycling (NC) subjects and COC users. A secondary goal was to explore associations between menstrual pain as a covariate and rsFC.DesignObservational, longitudinal study.MethodsNC women (n = 24) and COC users (n = 17) underwent a resting-state EEG recording during the early follicular phase (EFP) and pre-ovulatory phase (POV), and the active pill phase (pill phase) and inactive phase (pause), respectively. Mean characteristic path length (mCPL), clustering coefficient (CC), and mean debiased weighted phase lag index (mdWPLI) were computed for 37 participants (NC = 21; COC = 16). Phase and group differences were examined using mixed MANOVA, while mixed MANCOVA assessed the influence of menstrual pain as a covariate.ResultsNo significant differences between MC or COC phases, as well as between groups, were found. Including menstrual pain as a covariate revealed significant phase*pain interactions for mCPL and CC, as well as significant group*pain interactions in mdWPLI. Post-hoc tests revealed a significant increase in mCPL from the pause to the pill phase.ConclusionThe preliminary findings suggest that menstrual pain may influence baseline brain network states, which may have potential implications for performance and injury risk in female athletes. Therefore, considering menstrual pain is crucial in both research and applied sports contexts.