THE INFLUENCE OF MENSTRUAL CYCLE PHASES ON MAXIMAL VOLUNTARY ISOMETRIC CONTRACTION AND RATING OF PERCEIVED EXERTION IN EUMENORRHEIC WOMEN

https://youtu.be/xsx9ydBdyl8 INTRODUCTION: Females experience cyclical hormonal changes across menstrual cycle phases (MCPs), driven by variations in sex hormone levels. These hormonal changes influence thermoregulation, perceived exertion, and neuromuscular control, contributing to physiological and performance fluctuations across MCPs. This study investigated the relationship between MCPs and differences in maximal voluntary isometric contractions (MVICs), neuromuscular responses, and ratings of perceived exertion (RPE). The hypothesis was that during the late follicular phase, MVIC would be highest because testosterone levels in females are generally highest then. Additionally, it was hypothesized that RPE would be highest during the luteal phase, as progesterone is typically elevated during this phase. METHODS: Nine eumenorrheic females (27.8±7.2 years old), who were not using hormonal birth control contraceptives were enrolled for a total of 2 months, allowing for two complete MCPs to be completed. Data collection began during the menstruation phase of each participant’s cycle to ensure consistency. During each lab visit, the participants performed a dynamic warm-up followed by 3, 6-second MVICs for knee extension and flexion, at 60 degrees using a Biodex dynamometer, and the participants rested 15 seconds between sets. Upon completion, the participants rated their RPE using a 0–10 scale. RESULTS: The results from the three separate mixed factorial ANOVAs were not statistically significant. The MVIC when the participants performed knee extension was not significant (F(3,2336.22)=2.34, p=0.10, η2p=0.23). The MVIC when the participants performed knee flexion was not significant (F(3,640.85)=2.08, p=0.13, η2p=0.21). Psychological responses to exertion measured by RPE was not statistically significant (F(3, 0.31)=0.14, p=0.93, η2p=0.02). CONCLUSIONS: Studying performance across MCPs is essential for advancing female-specific exercise science and developing phase-based training strategies. Based on these findings, it is still important to continue understanding the MCP’s physiological responses and fluctuations. Future studies should recruit a larger number of participants to gain more insight, and data could be grouped based on age, birth control contraceptive method, and dosage. The results of this study underscore how training status, hormonal fluctuations, and perceptual responses interact to influence female performance. For clinical exercise physiologists, these findings are especially relevant, as they can help guide exercise prescriptions and training programs that account for hormonal variations. By integrating physiological assessment, femtech technology, and applied exercise science, this research establishes a foundation for future exploration of phase-specific training adaptations and aids in designing programs that better support women’s health and athletic potential.