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The menstrual cycle and exercise: performance, muscle glycogen, and substrate responses
B J Nicklas1, A C Hackney, R L Sharp
1Exercise Biochemistry Laboratory, Iowa State University, Ames 50010.
International Journal of Sports Medicine
|August 1, 1989
Summary
Exercise performance and muscle glycogen stores are enhanced during the late luteal phase (LP) of the menstrual cycle compared to the follicular phase (FP). This suggests athletic performance may be influenced by menstrual cycle phase.
Area of Science:
- Exercise Physiology
- Endocrinology
- Sports Science
Background:
- Menstrual cycle phases influence hormonal profiles, potentially affecting physiological responses to exercise.
- Understanding these fluctuations is crucial for optimizing athletic training and performance.
Purpose of the Study:
- To investigate the impact of the midluteal phase (LP) versus the midfollicular phase (FP) of the menstrual cycle on exercise performance and muscle glycogen metabolism.
- To determine if exercise capacity and muscle glycogen repletion/utilization differ between these two menstrual cycle phases.
Main Methods:
- Six eumenorrheic females underwent exercise tests until exhaustion (EE) at 70% VO2max during both LP and FP.
- Preceding each EE test involved a depletion exercise bout (DE) and 3 days of rest/diet control.
- Muscle biopsies (vastus lateralis) were analyzed for glycogen content post-DE, pre-EE, and post-EE.
Main Results:
- A trend for longer EE duration was observed during the LP (139.2 min) compared to the FP (126 min) (P < 0.07).
- Muscle glycogen repletion following DE was significantly greater during the LP than FP (P = 0.05).
- Glycogen utilization during EE did not significantly differ between the LP and FP (P = 0.17).
Conclusions:
- Exercise performance and muscle glycogen content appear to be enhanced during the LP of the menstrual cycle.
- These findings suggest that athletic performance can be influenced by the phase of the menstrual cycle.