Strength and power throughout the menstrual cycle
Date
2020
Authors
Miller, Amber D., author
Tracy, Brian, advisor
Braun, Barry, committee member
Cox-York, Kimberly, committee member
Journal Title
Journal ISSN
Volume Title
Abstract
Purpose: The purpose was to determine if maximal muscle performance varies across the menstrual cycle because historically this measurement has been left out of research and women report feeling differences between phases. Strength and ballistic force production were measured in normally cycling eumenorrheic women and in women on hormonal birth control. We expected greater performance during the follicular vs. luteal phase because of fluctuating hormones, specifically estrogen, for the normally cycling women and more constant values for women on birth control because of the lack of fluctuating hormones due to effects of birth control. Methods: Participants were physically active women between 18-40 years who were either 1) eumenorrheic and not taking hormonal birth control (N=13), or 2) taking birth control (N=10). Ovulation was determined via body temperature and LH strips, and along with menses, was tracked for one full cycle prior to strength testing as well as during their two months of strength testing. Identical assessments were performed on four visits in the luteal and follicular phases over two consecutive months of menstrual cycles. Tests included leg and arm strength, ballistic force production, and vertical jump. Results: Comparisons were made between the luteal and follicular phases within subjects and between the normally cycling and hormonal birth control groups. No significant differences were found in for strength or ballistic functional measures between menstrual phases or between the groups (p=>0.05). Conclusions: Meaningful differences between phases would suggest that hormonal fluctuations affect muscle performance. We found no difference in muscle function between follicular and luteal phases. This suggests that the hormonal variation during the menstrual cycle is insufficient to alter maximal neuromuscular output. One possibility is that the relatively low number of participants hampered the ability to detect differences. If there are no differences between phases, the female athlete does not need to adjust their training and competition schedules.