The recovery process across the menstrual cycle in recreational female athletes: a prospective cohort study.

Purpose: The relationship between post-exercise inflammation and menstrual cycle (MC) phases in female athletes is poorly understood. This study assessed recovery, measured via high-sensitivity C-reactive protein (hs-CRP), after game days in recreational female athletes and whether it differed by MC phase. Methods: Nineteen participants provided demographic and MC data and underwent point-of-care blood testing for hs-CRP on game day (GD) - 1, + 1, + 2, and + 3 on two occasions (n = 119 data collection days). Four MC phases were estimated using ovulation tests and self-reported bleed data. Random-effects regression models examined associations between GD and hs-CRP, and possible interactions between GD and MC. Backwards stepwise regression included the covariates; age, sport type, fatigue level, minutes played, MC symptoms, and BMI. Results: Compared to baseline (GD-1), hs-CRP was 25.0% (95% confidence interval:12.49,37.45) higher on GD + 1, 10.83% (- 1.66,23.31) higher on GD + 2 and returned to baseline by GD + 3 (- 3.20%(- 15.78,9.39)). Results were robust in adjusted models. A significant interaction between gameday and MC phase on hs-CRP revealed a 62.9% larger GD + 1 peak (40.31, 85.66) than GD-1 during the late luteal (LL) phase. Conclusion: Hs-CRP peaked on GD + 1, remained elevated on GD + 2, returned to baseline by GD + 3, with evidence suggesting inflammation was higher on GD + 1 in the LL phase. Supplementary Information: The online version contains supplementary material available at 10.1007/s11332-025-01552-1.