Farwa Baber, Jana Jaklová Dytrtová, Michal Jakl, Noor Ul An Babar
Current evidence does not support a uniform menstrual phase effect on biomarkers of exercise-induced muscle damage or inflammation. Menstrual status should be treated as a biologically relevant design and interpretation variable, not as a deterministic explanation for biomarker variation. Future studies require cycle-aware designs combining prospective tracking, ovulation confirmation, estradiol and progesterone assessment, standardized exercise stimuli, biomarker-specific sampling, and repeated-measures analyses.
BACKGROUND: Menstrual cycle fluctuations in estradiol and progesterone may influence post-exercise biomarkers of muscle damage, inflammation, and recovery, but interpretation is limited by heterogeneous protocols, inconsistent phase verification, and poorly aligned sampling.
OBJECTIVE: To critically synthesize evidence on whether menstrual cycle phase modulates exercise-induced muscle damage, inflammatory, immune-cell, or recovery-related biomarker responses in naturally menstruating women not using hormonal contraception.
METHODS: PubMed, Scopus, and Web of Science were searched to June 21, 2026. Eligible studies assessed biomarkers or recovery outcomes after acute exercise or sport-related exposure across at least two menstrual cycle phases. Phase verification, exercise models, biomarker selection, sampling schedules, and methodological quality were synthesized narratively.
RESULTS: Eighteen studies were included. Exercise stimulus and sampling time were more consistent determinants of biomarker responses than menstrual phase labels alone. CK and IL-6 showed clear exercise-related, time-dependent responses, whereas phase-related differences were inconsistent across exercise models, endocrine contrasts, and verification methods. Emerging outcomes, including hepcidin, hs-CRP, oxidative-stress markers, immune-cell subsets, salivary IL-6, DOMS, and neuromuscular recovery, broadened the field but remained too heterogeneous for conclusions. Incomplete endocrine verification, non-equivalent phase definitions, small samples, and mismatched sampling limited interpretation.
CONCLUSION: Current evidence does not support a uniform menstrual phase effect on biomarkers of exercise-induced muscle damage or inflammation. Menstrual status should be treated as a biologically relevant design and interpretation variable, not as a deterministic explanation for biomarker variation. Future studies require cycle-aware designs combining prospective tracking, ovulation confirmation, estradiol and progesterone assessment, standardized exercise stimuli, biomarker-specific sampling, and repeated-measures analyses.