The effects of the menstrual cycle on physical and psychological parameters in female athletes.

Hormonal fluctuations across the menstrual cycle may influence physical performance and psychological well-being in female athletes. However, current evidence remains heterogeneous, partly due to inconsistent cycle phase determination and task-dependent outcome measures. This study aimed to describe phase-dependent changes in physical and psychological parameters across six hormonally validated menstrual cycle phases and to examine associations between these domains. Eighteen eumenorrheic female athletes from various sports (age 18-30 years; 23.6 ± 3.8 years) were assessed across six menstrual cycle phases. Dynamic maximal strength in the half squat, isometric handgrip strength, and psychological variables including POMS subscales, motivation, sleep quality, and perceived exertion were measured. Significant phase effects were observed for half-squat performance, isometric handgrip strength, and several POMS subscales. Main effect p values ranged from p = .029 to p < .001, with partial eta-squared effect sizes between η²p = .13 and 0.98. Half-squat performance peaked in the late follicular phase and at ovulation and was lowest in the late luteal phase. Handgrip strength reached its highest values during the late luteal phase. Psychological measures showed increased fatigue and depression scores and reduced vigor in the late luteal phase. No phase effects were found for motivation, sleep quality, or perceived exertion (p = .424-0.698). At the individual level, half-squat performance was negatively associated with POMS depression scores (r = - .60, p = .009). All other correlations were non-significant, with r values ranging from - 0.44 to - 0.47 and p values between 0.052 and 0.849. A pattern-oriented and individually adaptive training approach is recommended, including the development of menstrual cycle literacy among athletes and support staff. A monitoring strategy using a small number of informative strength and well-being markers, combined with regular feedback, may help adjust training loads to individual menstrual cycle patterns.