Menstrual Cycle and Athletic Performance

Despite its growing presence in the world of sport (fortunately), women remain underrepresented in sports-performance research compared with men. In fact, despite the fact that there are numerous physiological and anatomical characteristics that differentiate men from women, scientific studies are still predominantly focused on men, which means that training or recovery strategies that have not been tested in this population are often used in women.

One of the characteristics that most differentiates men and women is their hormonal status, and specifically the menstrual cycle. While men have a more "stable" hormonal status over time, women have variations throughout the menstrual cycle in hormones that can have (a priori) important consequences on performance, such as estrogens (which are an anabolic stimulus, i.e. the creation/repair of muscle tissue, as well as increasing the antioxidant response and the stabilization of the membrane of muscle fibers, which could reduce muscle damage) or progesterone (which seems to exert opposite actions to estrogen, i.e., muscle catabolism). ¹ In fact, the variations in these hormones throughout the menstrual cycle mean that we can differentiate three phases in general: the follicular phase, where there are low levels of estrogen and progesterone, and which begins with menstrual bleeding; the ovulatory phase, where high levels of estrogen and low levels of progesterone are found; and the luteal phase, where high levels of both estrogen and progesterone are found (Figure 1).

Given the potential influence of estrogen and progesterone on processes such as muscle anabolism, it has been proposed that throughout the menstrual cycle there could be variations in sports performance or in the adaptations produced with training. For example, a priori it could be thought that greater muscle adaptations will occur during the ovulatory phase, when estrogen levels are increased, while lower performance levels would occur during the early follicular phase, when estrogen levels are lower. But what does science say about it?

There are numerous studies that have tried to determine the possible variations in performance between the different menstrual phases. Therefore, one of the most efficient ways to summarize the evidence is to turn to systematic reviews: research articles that analyze the results of all the articles published so far on a certain topic. In this sense, a recent systematic review published in the prestigious journal Sports Medicine has tried to compare the sports performance of women during the early follicular phase (taken as the reference phase) with respect to other phases of the menstrual cycle. To do this, the authors searched for all studies that had analysed these differences in eumenorrheic women (i.e. women with a normal, unaltered menstrual cycle) and who also did not take contraceptives, to prevent these factors from affecting the results. ² Finally, 76 studies with more than 1000 participants met these criteria. When analysing these studies, the results showed great heterogeneity between studies, although in general no significant differences in performance (either strength or endurance) were observed between the different phases of the menstrual cycle. Another recent systematic review tried to carry out a similar analysis, but in this case focusing only on elite athletes, in whom even small variations in performance can be very important. ³ In this case, the authors found only 7 studies (including 314 elite athletes) that met the inclusion criteria, and again the results were similar: no clear differences in sports performance were observed between the different phases of the menstrual cycle.

Figure 1. Simplified diagram of the phases of the menstrual cycle.

Conclusions

Knowledge about the effects of the menstrual cycle on athletic performance remains limited, partly due to the scant research conducted on female athletes compared to the number of studies conducted on men. In addition, many of these studies have certain limitations, such as determining the phases of the menstrual cycle based on questionnaires rather than hormonal measurements. However, based on the existing evidence, the menstrual cycle does not consistently affect performance, although this may be due in part to the high variability between individuals and the variety of methodological designs used in the studies. Given these results, there is no evidence to support universal decisions about how to train or when to compete based on the phase of the menstrual cycle an athlete is in. However, it is always advisable to monitor the menstrual cycle of athletes to detect possible situations (e.g., stress, energy deficit, over-training) that are causing abnormalities in it.

AUTHOR

Pedro Valenzuela
Researcher in the Physiology Unit of the University of Alcalá and in the Performance Control Unit at the Sports Medicine Center (AEPSAD, CAR of Madrid).
Web: www.fissac.com

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References

1. Lowe DA, Baltgalvis KA, Greising SM. Mechanisms behind Estrogens’ Beneficial Effect on Muscle Strength in Females. Exerc Sport Sci Rev. 2010;38(2):61-67. doi:10.1097/JES.0b013e3181d496bc.Mechanisms
2. McNulty KL, Elliott-Sale KJ, Dolan E, et al. The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis. Sport Med. 2020;50(10):1813-1827. doi:10.1007/s40279-020-01319-3
3. Meignié A, Duclos M, Carling C, et al. The Effects of Menstrual Cycle Phase on Elite Athlete Performance: A Critical and Systematic Review. Front Physiol. 2021;12(May). doi:10.3389/fphys.2021.654585