A new study reveals that while your menstrual cycle influences the function of your heart’s autonomic nervous system, your physical fitness, motivation, and overall mood remain significantly stable throughout the month.
Research: Effects of the menstrual cycle on the autonomic nervous system, muscle strength, and mood states. Image credit: Pormezz/Shutterstock.com
recent scientific report This study investigated the influence of menstrual cycle stage on autonomic cardiac function, neuromuscular performance, and psychological status in naturally menstruating women.
Menstrual cycle and physiology
The menstrual cycle (MC) is a recurring physiological process characterized by periodic fluctuations in pituitary hormones such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), and steroid sex hormones such as estrogen and progesterone. These hormonal changes define different phases of the cycle and drive a cascade of coordinated physiological adaptations.
Fluctuations in hormone levels control multiple systems, particularly the autonomic nervous system (ANS), neuromuscular performance, and mood. Although the MC stage is recognized as a factor influencing athletic performance and health status, existing evidence remains inconsistent and is often hampered by the underrepresentation of women in sports science research.
Hormonal fluctuations across the MC are thought to alter ANS activity as assessed by heart rate variability (HRV). HRV serves as a non-invasive indicator of physiological stress, recovery, and adaptation and reflects the dynamic interaction between parasympathetic and sympathetic branches. Although metrics such as root mean square sequential difference (RMSSD), high frequency power (HF), and standard deviation of beat-to-beat instantaneous variation (SD1) have been well validated, most studies have focused on male populations and the influence of MC phase on HRV is not well characterized.
Neuromuscular performance, including force production, can also vary across the MC and can be enhanced by estrogen or weakened by progesterone. However, research results are mixed, with reports ranging from noticeable changes in performance to negligible fluctuations in strength and function across the cycle.
Importantly, the combined control of HRV and muscle strength across the MC has not been systematically investigated. This lack of integrative analysis is a significant research gap and impedes the development of individualized training and performance strategies for female athletes.
Evaluation of the impact of the MC phase on cardiac and physiological measurements
The current observational study utilized a within-participant repeated measures design to assess physiological and neuromuscular changes across three menstrual cycle phases: menstruation (Mens), estimated late follicular phase (Foll-late), and estimated mid-luteal phase (Lut-mid). After a 1-month screening period that included menstrual diary tracking and urine LH testing, 15 healthy, recreationally active, naturally menstruating women with a mean age of 24.3 years were enrolled.
Eligibility criteria included participation in 2–4 physical activity sessions per week, regular MC (21–35 days), no use of hormonal contraception for at least 6 months, and low risk of menstrual disorders (LEAF-Q score <8). Participants using copper intrauterine devices (IUDs) were included. However, patients were excluded if they had anovulation (confirmed by urine LH test), lower extremity injury, or started hormonal contraception during the study.
Each participant participated in a familiarization session and three experimental sessions, each scheduled simultaneously with a separate MC phase. At each session, participants completed a Profile of Mood States (POMS) questionnaire, followed by a 5-min resting HRV recording, a standardized warm-up, and three maximal voluntary isometric contractions (MVC) of the knee extensors.
Menstrual cycle stage was determined by a combination of menstrual diaries and urinary ovulation tests. Mens (days 1-4, low estrogen and progesterone), Presumptive Foll-late (days 11-13, high estrogen, low progesterone), and Presumptive Lut-mid (days 21-23, elevated estrogen and progesterone). The testing schedule was individualized to each participant’s cycle characteristics. Hormone concentrations were not directly measured.
Mid-luteal phase is associated with decreased vagal nerve activity
Participants’ mean LEAF-Q score was 2.7 ± 1.8, suggesting minimal risk of reduced energy availability and low likelihood of MC failure. The average cycle length was 29.1 days, and menstruation lasted an average of 5.1 days. Participants were randomly assigned to start at different menstrual periods.
Menstrual phase had a significant effect on the vagal-mediated HRV index, which was significantly lower during mid-luteal phase estimation than during the menstrual and late follicular phases. One participant’s HRV data was excluded due to poor signal quality, so 14 participants were included in the HRV analysis.
Although a phase effect was observed in SD2, post hoc comparisons were not significant. These findings indicate a decrease in cardiac vagal control during the presumptive mid-luteal phase. Supports HRV as a sensitive marker of autonomic fluctuations across the menstrual cycle.
No significant differences were found in maximal voluntary contraction (MVC), rate of force development (RFD), electromyographic (EMG) activity, or neuromuscular efficiency (NME) across the MC phase. Psychological outcomes, including motivation, total mood disorder (TMD), and most POMS subscales, also did not show significant phase-related changes. An exception was observed for the POMS depression subscale score. Scores were elevated in the late follicular phase compared with the mid-luteal phase. Although TMD scores were not significantly different between phases, some variability was observed.
Vitality was positively correlated with EMG activity during the early force development phase of contraction, whereas normalized frequency-domain HRV index was correlated with rate of force development (RFD). Specifically, higher LFnu values were associated with greater RFD, and higher HFnu values were associated with lower RFD.
No significant correlations were found between HRV index and psychological measures. No significant association was found between HRV index and maximal muscle strength, EMG, or NME. These results emphasize selected physiological and psychological correlates that primarily link autonomic and neuromuscular responses to specific psychological states, rather than broad intervariable associations.
Researchers also reported substantial inter- and intra-individual variability, suggesting that physiological and psychological responses to menstrual cycle stages may vary widely between women.
Most performance metrics remained stable throughout
The current study demonstrated that in healthy, naturally menstruating, active women, HRV indices fluctuate across the menstrual cycle, with a significant decrease in vagal-mediated HRV during the estimated mid-luteal phase.
These results indicate that, although hormone concentrations were not directly measured, autonomic cardiac function changes with each stage of the menstrual cycle, consistent with hormone-related autonomic changes. Conversely, muscle strength, overall mood, and motivation were consistent throughout the cycle, with the exception of higher scores on the POMS depression subscale during the late follicular phase, indicating that these aspects of performance and well-being may be less influenced by the MC phase.
This finding is especially true for naturally menstruating women who are healthy, recreationally active, have regular menstrual cycles, and are at low risk for menstrual abnormalities. Therefore, these are not necessarily generalizable to women with menstrual disorders, lack of energy, use of hormonal contraceptives, or different athletic populations.
Because estrogen and progesterone concentrations were not directly measured, this result should be interpreted as evidence of menstrual cycle phase differences in autonomic regulation rather than as evidence that specific hormonal changes caused the observed HRV fluctuations.
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Reference magazines:
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Serrano, H. M., Gounod, N., and Lavier, G. (2026). The effects of the menstrual cycle on the autonomic nervous system, muscle strength, and mood states. scientific report. Doi: https://doi.org/10.1038/s41598-026-56802-0. https://www.nature.com/articles/s41598-026-56802-0
