The Impact of Menstrual Cycle Phase and Hormonal Contraception on the Risk of Anterior Cruciate Ligament (ACL) Injury and on Physical Performance and Motor Abilities in Women — A Narrative Review
Abstract
Background: Female athletes sustain anterior cruciate ligament (ACL) injuries two to eight times more often than males in comparable sports, and cyclical fluctuations of ovarian hormones are among the most frequently invoked female-specific explanations. The same hormones are also assumed to shape endurance, strength and motor abilities across the cycle. Aim: To synthesise and critically appraise evidence from the last decades on how menstrual cycle phase and hormonal contraceptive (HC) use influence ACL injury risk, knee joint laxity and neuromuscular control, and on how they influence aerobic capacity, strength, power and motor abilities in women. Methods: A narrative review of peer-reviewed original studies, systematic reviews and meta-analyses identified in PubMed, Scopus, Web of Science and Google Scholar was performed. Results: ACL injury risk is highest in the pre-ovulatory and ovulatory phases, when peak oestrogen coincides with increased anterior knee laxity and general joint laxity, whereas the luteal phase appears least associated with injury. Evidence on laxity is nevertheless inconsistent, and increased passive laxity does not translate uniformly into altered biomechanics. Oral contraceptives may modestly lower ACL injury risk in case-control data, but rigorous cohort designs suggest this reflects bias rather than a true protective effect. For performance, group-level effects of cycle phase on strength, power and endurance are trivial and inconsistent, although perceived performance and symptom burden fluctuate markedly. HC use exerts, at most, trivial group-level effects on performance. Conclusions: Cycle phase and HC modify passive stability and perceived function more than objective performance. Prevention and training should rely on individualised menstrual tracking, neuromuscular training and multidimensional screening rather than uniform phase-based protocols or routine contraceptive prescription.