Effects of Menstrual Cycle Phases on Athletic Performance and Related Physiological Outcomes. A Systematic Review of Studies Using High Methodological Standards.

Abstract

Whether different menstrual cycle (MC) phases are associated with differences in athletic performance is a constant scientific debate. Phase verification without actual sex hormone determination and heterogenous cohorts complicate the analysis. Therefore, this review only includes studies in which 17ß-oestradiol, progesterone, and luteinizing hormone we measured. The aim was to assess the prevalence of these methodological standards and determine the representativeness of elite athletes. Further, the associations between MC phase and athletic performance were analyzed. Four databases were searched for studies investigating athletic performance and performance-related outcomes in ≥2 phases in eumenorrheic females. 19 studies (total n = 279, 25.6 ± 3.6 years, mean sample size n = 13.9 ± 7) were included, with elite athletes underrepresented. Most compared three phases, particularly the early follicular (EF) phase was used. 58 % reported significant phase effects on at least one performance-related outcome, although the direction and magnitude varied between studies. The EF was identified as unfavorable for VO_2max by one, and for peak power by two studies. Submaximal ventilation was reduced during the EF. Maximum and explosive strength remained largely unaffected. Neuromuscular coordination was improved during ovulation. A medium to high risk of bias was identified in the randomization and reported outcomes. Despite focusing on studies with high methodological standards, the heterogeneity of phases and populations studied complicate a systematic analysis. The prevalence of serum hormone analysis in elite sports appeared to be poor. The risk of bias suggests to critically approach conclusions about the presence or absence of MC effects.