The influence of the menstrual cycle on sleep and recovery-stress states in female swim athletes during a 10-day training camp

Recovery is essential for athletes to adapt, maintain performance, and prevent overtraining. Hormonal fluctuations during the menstrual cycle can influence recovery, sleep, and performance, particularly during the luteal phase, characterized by elevated progesterone levels. However, current evidence remains inconsistent. This study examined the influence of menstrual cycle phase and menstrual symptoms on sleep and recovery-stress states in nine eumenorrheic female swimmers during a 10-day training camp. Athletes were monitored with actigraphy and assessed twice daily using the Short Recovery and Stress Scale (SRSS). Menstrual cycle phases were determined via the backward-counting method, and symptom frequency was assessed using the Menstrual Symptom index (MSi). Moreover, a pre- and post-camp 4 × 50 m broken swim protocol was conducted to assess performance improvements achieved during the training camp. The mid-luteal phase was associated with lower recovery and higher stress states. No significant differences were found in subjective or objective sleep parameters across phases. Additionally, all athletes exhibited performance improvements from pre- to post-test. Although sleep parameters were unaffected, the findings suggest that menstrual cycle phases may influence recovery and adaptation. Incorporating menstrual health into recovery strategies could support more individualized training planning.