Related Experiment Video
Updated: Jun 16, 2026
Muscle Imbalances: Testing and Training Functional Eccentric Hamstring Strength in Athletic Populations
Published on: May 1, 2018
The effect of menstrual-cycle phase on hamstring extensibility and muscle stiffness
David R Bell1, Megan P Myrick, J Troy Blackburn
1Dept of Exercise and Sport Science, University of North Carolina at Chapel Hill, USA.
Context:
Preventing noncontact ACL injuries has been a major focus of athletic trainers and researchers. One factor that may influence female noncontact ACL injury is the fluctuating concentrations of hormones in the body.
Objective:
To determine whether muscle properties change across the menstrual cycle.
Design:
Repeated measures. Testing was performed within 3 d after the onset of menses and ovulation. Repeated-measures ANOVAs were used to determine changes in variables across the menstrual cycle, and Pearson correlations were used to determine relationships between variables.
Participants:
8 women with normal menstrual cycles.
Main Outcome Measures:
Active hamstring stiffness and hamstring extensibility.
Results:
Hamstring extensibility (P = .003) increased at the ovulation testing session but hamstring muscle stiffness (P = .66) did not.
Conclusions:
The results indicate that hamstring muscle stiffness did not change across the menstrual cycle and hamstring extensibility increased at ovulation, when estrogen concentration increases.
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