Date of Award

Spring 5-28-2026

Document Type

Open Access Thesis

Department

Kinesiology

First Advisor

Kevin Dames

Abstract

Context: Hormonal fluctuations associated with the menstrual cycle contribute to modifications in joint laxity. Conflicting evidence supports increased ligamentous injury risk and altered postural control in response to these cyclic changes. Objective: To quantify changes in passive joint flexibility and dynamic postural control across the menses and luteal phases of the menstrual cycle. Design: Repeated measures. Setting: Research laboratory. Participants: Thirteen healthy females (20 [1] y, 1.62 [0.06] m, 67.42 [11.75] kg) with a regular menstrual cycle over the last twelve months volunteered. Interventions: Participants performed five static flexibility tests and three single-leg drop landings onto a force plate with their dominant limb. Time to stabilization (TTS) was calculated based on vertical (V) and anterior-posterior (AP) force vectors. Center of pressure (CoP) range and excursion were calculated prior to and following peak vertical force. Testing occurred during menses (days 1-6) and the luteal phase (days 9-12) of the menstrual cycle. Results: V TTS was 0.09s faster on average during menses (p = .022). Otherwise, no differences in flexibility or landing mechanics measures were detected between sessions (all p > 0.05). Yet, ankle, knee, and pelvic flexibility measures each correlated with kinetic and/or kinematic stability features across sessions. Conclusions: Our findings suggest gross flexibility and neuromuscular coordination in drop landing are generally homeostatic in nature but relationships between these measures may be influenced by the menstrual cycle. Regardless of cycle phase, ankle dorsiflexion is strongly linked with drop landing stabilization.

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