Menstrual Cycle and Women's Performance

Background and rationale: Female physiology changes across menstrual cycle phases, which may influence neuromuscular performance, perceived symptoms, and selected tissue/mechanical properties. Current evidence is heterogeneous, partly due to methodological differences in cycle-phase identification and measurement protocols. This study aims to provide standardized data from repeated within-subject assessments across the menstrual cycle. Objectives: Primary objective is to evaluate associations between menstrual cycle phase and selected performance-related outcomes in physically active women. Secondary objectives are to explore phase-related differences in musculoskeletal parameters, body composition outputs, and self-reported symptoms. Study design: Prospective, repeated-measures observational study. Each participant is measured repeatedly across predefined menstrual cycle phases. Participants: Women from the general population, 18-35 years, with occasional to recreational physical activity level. Procedures: Screening and eligibility confirmation according to protocol criteria. Menstrual cycle tracking via mobile application for approximately 2 months. Three laboratory visits timed to predefined cycle phases. At each visit, non-invasive assessments are performed, including: lower-limb strength/performance testing, assessment of muscle and tendon mechanical properties, body composition measurement, recording of subjectively perceived menstrual-related symptoms. Outcomes: Main outcomes include phase-specific differences/associations in selected performance and musculoskeletal variables; additional outcomes include symptom profiles and selected body-composition variables. Duration and setting: Individual participation lasts approximately 2 months including cycle tracking and 3 lab visits (approximately 60-90 minutes per visit). Study procedures are conducted at FTVS UK (Prague). Ethics and data protection: Participation is voluntary, and participants may withdraw at any time without giving a reason. Data are processed in compliance with applicable data-protection regulations (including GDPR), pseudonymized for analysis, and reported in aggregate/anonymized form. The study is conducted according to institutional ethics approval and the Declaration of Helsinki.