The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis

The Effects of Menstrual Cycle Phase on Exercise Performance in Eumenorrheic Women: A Systematic Review and Meta-Analysis. Kelly Lee McNulty, Kirsty Jayne Elliott-Sale, and colleagues. Sports Medicine, 2020. DOI: 10.1007/s40279-020-01319-3. PMID: 32661839. https://doi.org/10.1007/s40279-020-01319-3

Study type: Systematic review and meta-analysis. Open access; this note is based on the full text.

Does exercise performance reliably change across the menstrual cycle? The review included 78 studies involving 1,193 women with regular natural cycles. The researchers combined strength and endurance results, although not every study supplied data for every analysis. Performance was slightly lower on average during the early follicular phase, around the beginning of menstruation. The estimated difference was very small, and its uncertainty included no difference. When the analysis was restricted to better-quality studies, the average effect was close to zero. Results also varied considerably between studies.

A small group average cannot predict what will happen to one woman. These comparisons also do not establish which hormonal mechanism caused any difference, or whether a cycle-based training plan would improve results. The paper examines performance across cycle phases. It does not directly test recovery meals, carbohydrate requirements, or protein doses, so nutrition prescriptions cannot be derived from it.

So What Does This Actually Mean for You?

You do not need to assume that your period automatically makes you weaker or less capable of endurance exercise. At the same time, the small average effect is no reason to dismiss a pattern you repeatedly experience yourself. The authors favor an individual approach because a calendar-based rule would conceal substantial variation. For most recreational exercisers, the average difference found here is unlikely to have much practical meaning. For an elite athlete, very small differences may matter, but they still need to be understood in that athlete's own context. The useful distinction is between noticing your own response and treating a predicted cycle phase as a fixed limit on what your body can do.

Where the Evidence Runs Out

Most studies were small and of low or very low quality. Many did not confirm cycle phases adequately using hormone measurements and ovulation testing. The review excluded hormonal-contraceptive users and women with menstrual dysfunction. Better studies need reliable phase verification and repeated, meaningful performance measures before stronger guidance is possible.

Why We Cite This Source

We cite this paper when evaluating claims that menstrual hormones require universal changes to exercise or recovery routines. Its value is in showing the size and uncertainty of measured performance differences, helping readers avoid turning a biological explanation into an unsupported rule.

The Bottom Line in One Paragraph

This analysis found, at most, a very small average performance dip around the start of menstruation, with substantial uncertainty. It supports attention to individual responses rather than a universal cycle schedule. It provides no direct evidence for changing recovery nutrition by phase.

Read the Original Research: DOI https://doi.org/10.1007/s40279-020-01319-3 · PubMed https://pubmed.ncbi.nlm.nih.gov/32661839/ · Journal https://link.springer.com/article/10.1007/s40279-020-01319-3