O007 Menstrual cycle phase classification methods and the relationship with sleep, mood, and performance in elite female athletes

Abstract Introduction Female athletes are often excluded from sports-science research due to hormonal variations across the menstrual cycle. Effects of menstrual cycle phase on outcomes are inconclusive likely due to between-study variation in phase classification. We aimed to test if the relationship between menstrual cycle phase and sleep, mood, and performance differed depending on whether a continuous, 2-phase, 3-phase, or 4-phase approach was used to classify cycle phase. Methods Elite Australian Rules footballers reporting a regular menstrual cycle and not on contraception (N=18, M-age=24.9±5.1) were recruited. Over two weeks, they completed continuous sleep/wake monitoring via actigraphy and sleep diaries, daily self-reported sleep quality, mood, and performance ratings, and five sessions of cognitive (vigilant attention) and physical (ecological kicking task) performance testing. Using baseline self-report data, menstrual cycle phase for each day of the study was inferred using a continuous (percentage through the cycle), 2-phase (follicular, luteal), 3-phase (menses, mid-late follicular, luteal), and 4-phase (menses, mid-late follicular, early-mid luteal, pre-menses) model. Results No outcome was consistently predicted by all phase-models. Objective sleep efficiency was lower in menses according to the 3- and 4-phase models. Subjective mood and performance were higher in the mid-late follicular according to the 3-phase model. Discussion The relationships between menstrual cycle phase and sleep, mood, and performance depend on how menstrual cycle phases are classified. Discordant findings highlight the importance of methodological differences in athlete menstrual cycle research. The effects of the menstrual cycle phase need to be further studied using consistent and standardised classifications across studies.