Menstrual cycle effects on foot and ankle musculoeskeletal biomechanics: A systematic review and meta-analysis

Hormonal fluctuations throughout the menstrual cycle are associated with a higher prevalence of musculoskeletal injuries in women; however, their impact at the foot and ankle level remains underexplored. The aim of this systematic review and meta-analysis was to examine the potential biomechanical effect of the ovulatory phase on foot and ankle structure compared to other phases of the menstrual cycle, given its possible association with injury occurrence. A systematic search was conducted in PubMed, Scopus, Web Of Science, and Embase (last 10 years), following PRISMA guidelines. Cohort studies, non-randomized trials, and case-control studies were included. Quality assessment was performed using the JBI critical appraisal tool. A quantitative synthesis (meta-analysis) was performed for homogeneous variables (muscle stiffness). Fifteen studies were selected. The systematic review demonstrated increase in foot length, reduction in fascial thickness, and greater longitudinal arch collapse during the ovulatory phase. Tone and stiffness of the tibialis anterior and peroneus longus muscles were greater during the menstrual phase. During ovulation, lower stiffness was observed during active contraction and increased tibialis anterior activation. Greater postural sway and oscillation were recorded during ovulation in complex static tasks, and, along with the menstrual phase, in dynamic balance tests. The meta-analysis indicated a tendency towards lower tibialis anterior stiffness during the follicular phase compared to the ovulatory phase. The ovulatory phase appears to be associated with an interaction of structural alterations (ligament laxity and arch collapse) and neuromuscular changes (reduced muscle stiffness and inefficient motor control) that, together, could constitute a risk factor for local pathologies such as plantar fasciitis and chronic ankle instability. • Estrogen peaks during the cycle increase ligamentous laxity. • Adjusting training intensity to the cycle may prevent injuries in athletes. • Plantar fascia laxity and foot length are greater during ovulation. • Postural stability and balance change throughout the menstrual cycle.