The female menstrual cycle is characterized by hormonal fluctuations throughout its different phases that could affect strength, power and endurance capabilities. However, research on its effects on performance in elite athletes is scarce and, in some cases, the findings are contradictory.

In this context, the study “The Female Menstrual Cycles Effect on Strength and Power Parameters in High-Level Female Team Athletes (Marcus S. Dasa et al., 2021)” was developed, whose objectives were:

• To investigate the effect of the female menstrual cycle on strength and power performance in high-level female team athletes.
• To examine whether eumenorrheic (normal menstruation) participants with natural hormonal fluctuations showed improved performance in the follicular versus luteal phase compared to participants using hormonal contraceptives.

Athlete profile and evaluation protocol

A total of 29 female athletes (8 eumenorrheic participants and 21 using hormonal contraceptives), belonging to 6 soccer, handball and volleyball teams from Hordaland County (Norway), completed the study after a 6-week period.

The evaluation protocol was based on several tests:

• Maximal voluntary isometric grip strength of the dominant hand (to measure the maximum voluntary force applied when resistance is insurmountable).
• 20-meter sprint (to determine maximal aerobic power).
• Countermovement jump (to measure lower body power and lower extremity strength).
• Leg press (to measure relative maximal power).

Based on self-report of hormonal contraceptive use, participants were divided into two groups: non-hormonal contraceptive and hormonal contraceptive.

The follicular phase (from the first day of menstruation until the ovulatory phase) and luteal phase (beginning after ovulation and extending until the time of a new menses) were confirmed by hormonal analysis in the non-hormonal contraceptive group to ensure correct group assignment and the validity of the self-reported menstrual phase. In the hormonal contraceptive group, self-reported onset of menses was used for follicular and luteal phase assignment.

Main results

• There were no statistically significant changes for the two different phases of the menstrual cycle, in terms of physical performance for the whole group.
• There were no significant differences between the groups during the menstrual cycle in any of the tests, except for the countermovement jump, which showed slight non-significant weekly variations in the non-hormonal contraceptive group throughout the menstrual cycle.

Final Considerations

As highlighted in previous studies, different hormonal contraceptive methods can exert various effects on performance.¹ And yet, to our knowledge, there is no study investigating the effect of different contraceptive methods on sports performance in top-level competitive athletes. Therefore, this could be an interesting line of research to follow in future studies, by separating the different hormonal contraceptive methods used into groups.

On the other hand, it is worth pointing out some of the possible limitations of the study summarized here: although no statistical differences were observed between the two groups, there was some interindividual variability in both. In addition, the final sample size was small. And although the tests were originally scheduled for the same day throughout the study period to account for circadian variations, due to national team obligations and training/competition schedules that fluctuate in the preseason, some participants were tested outside the marked time. This could have affected the results, as circadian rhythm has been shown to affect performance in strength and power efforts.²

In any case, the main conclusion of the study shows that the menstrual cycle does not alter acute strength and power performance in high-level female team athletes.

However, it is important to note that the results should be interpreted with caution, due to the aforementioned limitations of the study.

Sources

1. Myllyaho, M. M., Ihalainen, J. K., Hackney, A. C., Valtonen, M., Nummela, A., Vaara, E., et al. (2018). Hormonal contraceptive use does not affect strength, endurance, or body composition adaptations to combined strength and endurance training in women. J. Strength Cond. Res. 35, 449–457. doi: 10.1519/jsc.0000000000002713
2. Grgic, J., Lazinica, B., Garofolini, A., Schoenfeld, B. J., Saner, N. J., Mikulic, P. et al. (2019). The effects of time of day-specific resistance training on adaptations in skeletal muscle hypertrophy and muscle strength: a systematic review and meta- analysis. Chronobiol. Int. 36, 449–460. doi: 10.1080/07420528.2019.1567524