The Relationship Between Menstrual Cycle Characteristics and Neuromuscular Control During Lower-Limb Rehabilitation

James Wilburn

University of Bradford, Bradford, United Kingdom.

Abstract

Background: Women sustain non-contact anterior cruciate ligament (ACL) injuries at two to eight times the rate of men, and they make up a growing share of patients in lower-limb rehabilitation. Ovarian hormones change ligament compliance, corticospinal excitability, and muscle fatigability across the menstrual cycle. Most rehabilitation protocols still ignore this.

Aim: To synthesise the evidence linking menstrual cycle characteristics (phase, cycle regularity, symptom burden and hormonal contraceptive use) to neuromuscular control of the lower limb, and to translate it into a practical, phase-informed rehabilitation framework.

Methods: A narrative evidence synthesis of systematic reviews, meta-analyses and mechanistic studies in eumenorrheic women and hormonal contraceptive users, with emphasis on knee laxity, strength, motor unit behaviour, fatigability, proprioception and landing biomechanics.

Results: At group level, cycle phase has a trivial effect on maximal performance (pooled effect size −0.06 in the early follicular phase across 78 studies). Effects on the control side are larger and more consistent: anterior knee laxity rises around ovulation, knee-extensor fatigability and corticospinal excitability shift between phases, and low-threshold motor unit firing changes without any change in force output. Individual variation is large, so a single phase-based rule for all women is not supported.

Conclusion: Menstrual cycle characteristics should be tracked and used to individualise lower-limb rehabilitation, not to standardise it. We propose a five-step clinical framework: screen, track, monitor, adjust and re-test. It targets neuromuscular control rather than load alone.
the treatment.

Keywords: Menstrual cycle; Neuromuscular control; Anterior cruciate ligament; Knee laxity; Rehabilitation; Oestrogen; Progesterone; Hormonal contraception; Personalised physical therapy

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