Should You Plan Workouts Around Your Menstrual Cycle? New Study Says It's Not Necessary
- Alastair Hunt
- 1 day ago
- 6 min read
As more women engage in structured strength training, the question often arises: should workouts be adjusted to match menstrual cycle phases for better muscle gains? A new study by Colenso-Semple and colleagues, published in The Journal of Physiology, rigorously tested this idea and found no evidence that muscle protein synthesis or breakdown is influenced by menstrual cycle phase. In simple terms: your cycle may not matter nearly as much as consistency in your training.
As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Links to all studies at bottom of page.
What Was the Hypothesis?
Past research and popular belief have suggested that hormonal changes during the menstrual cycle, particularly rising oestrogen in the follicular phase (before ovulation) and higher progesterone in the luteal phase (after ovulation), could impact how well muscles respond to resistance training. The idea was that the follicular phase might offer a more “anabolic” or muscle-building environment, while the luteal phase might promote more muscle breakdown.
To test this, the researchers looked at both muscle protein synthesis (MPS: how fast your body builds new muscle protein) and myofibrillar protein breakdown (MPB: how fast your body breaks it down) during these two phases.
A Gold-Standard Study Design
The study enrolled 12 healthy women aged 18–30, all with regular menstrual cycles and not using hormonal contraception. Each participant underwent two six-day training blocks: one during the late follicular phase and the other during the mid-luteal phase. In each phase, they trained one leg (via knee extensions) while the other served as a control.
Importantly, the researchers confirmed menstrual phases with hormone tests, ovulation tracking and urinary hormone kits, a best-practice approach rarely seen in prior studies. Muscle biopsies, advanced stable isotope tracing (using deuterium oxide, or D2O), and metabolomic profiling (a broad look at circulating metabolic compounds) added further layers of precision.
What Did They Find?
Resistance training increased muscle protein synthesis, as expected.
However, there was no difference in muscle protein synthesis between the follicular and luteal phases.
Similarly, muscle protein breakdown was unaffected by menstrual cycle phase.
No meaningful shifts in blood metabolites (small molecules that reflect metabolic activity) were found between phases.
In other words, the hormonal fluctuations that naturally occur throughout a normal menstrual cycle did not alter the muscle’s response to strength training in this study.
To put it in numbers, muscle protein synthesis increased by about 14% in the exercised leg compared to the control, regardless of phase. That’s a meaningful boost from exercise, but it happened equally in both the follicular and luteal phases.
The findings suggest that there’s no clear advantage to scheduling strength training around your menstrual cycle, at least when it comes to building muscle. This challenges popular workout plans that advise training more intensively in the follicular phase or avoiding resistance work in the luteal phase due to supposed “catabolic” effects.
The study also underscores the importance of not excluding women from exercise science research due to menstrual-related hormonal changes. Many past studies in sports and exercise science have left out female participants entirely, citing the menstrual cycle as a complicating factor. This work shows that concern may be overstated.
Practical Takeaways
Train Consistently, Not CyclicallyThere's no need to plan your workouts around your menstrual cycle unless you have individual reasons to do so, such as managing symptoms or energy levels.
Hormones Aren’t the Whole StoryAlthough hormones like oestrogen and progesterone fluctuate, their impact on muscle building in real-world training settings appears minimal, at least over short periods.
Listen to Your Body FirstWhile the study found no physiological difference in protein synthesis or breakdown, that doesn’t mean you won’t feel different throughout your cycle. Some women may notice changes in energy, motivation, or discomfort. It’s fine to adjust based on how you feel.
Don’t Skip Strength TrainingIf you’re healthy and not on hormonal contraception, this study supports training in any cycle phase, with no need for complex scheduling to optimise results.
Women Belong in Sports ScienceThis study also makes a broader point: with the right design and methods, we can and should include women in exercise research without fear of hormonal variability “muddying” the data.
Why This Study Stands Out
This is one of the few studies to use such comprehensive methods: repeated hormone measurements, within-subject design (so each woman serves as her own control), and long-term measurement of muscle protein synthesis. Many older studies relied on assumptions about cycle timing or used short, acute measurements that may not reflect real training outcomes.
It also carefully distinguishes between animal models and human physiology. Much of the original belief in oestrogen’s anabolic effects comes from rodent studies with ovariectomised animals (female animals that have undergone surgical removal of their ovaries), a condition that doesn't replicate normal human hormonal patterns.
Final Thoughts
The idea that your menstrual cycle should dictate your strength training plan has been popular in recent years, but this well-designed study shows that there's no muscle-building advantage to training in one phase over another. What matters most is showing up, working hard, and staying consistent. Hormones fluctuate, but your results won’t — as long as your training and recovery are on point.
For anyone wondering whether to delay workouts or switch phases based on their period, the answer seems simple: train when it works for you, not your hormone calendar.
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Alastair
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Related Studies & Resources
The study in review: Colenso-Semple LM, McKendry J, Lim C, Atherton PJ, Wilkinson DJ, Smith K, Phillips SM. Menstrual cycle phase does not influence muscle protein synthesis or whole-body myofibrillar proteolysis in response to resistance exercise. J Physiol. 2025 Mar;603(5):1109-1121. doi: 10.1113/JP287342. Epub 2024 Dec 4. PMID: 39630025; PMCID: PMC11870050.
Other
Kraemer WJ, Fragala MS, Ratamess NA. Evolution of resistance training in women: History and mechanisms for health and performance. Sports Med Health Sci. 2025 Feb 3;7(5):351-365. doi: 10.1016/j.smhs.2025.01.005. PMID: 40936659; PMCID: PMC12421175.
Zhao F, Su W, Sun Y, Wang J, Lu B, Yun H. Optimal resistance training parameters for improving bone mineral density in postmenopausal women: a systematic review and meta-analysis. J Orthop Surg Res. 2025 May 27;20(1):523. doi: 10.1186/s13018-025-05890-1. PMID: 40420105; PMCID: PMC12107943.
Shailendra P, Baldock KL, Li LSK, Bennie JA, Boyle T. Resistance Training and Mortality Risk: A Systematic Review and Meta-Analysis. Am J Prev Med. 2022 Aug;63(2):277-285. doi: 10.1016/j.amepre.2022.03.020. Epub 2022 May 20. PMID: 35599175.
Erickson KI, Voss MW, Prakash RS, Basak C, Szabo A, Chaddock L, Kim JS, Heo S, Alves H, White SM, Wojcicki TR, Mailey E, Vieira VJ, Martin SA, Pence BD, Woods JA, McAuley E, Kramer AF. Exercise training increases size of hippocampus and improves memory. Proc Natl Acad Sci U S A. 2011 Feb 15;108(7):3017-22. doi: 10.1073/pnas.1015950108. Epub 2011 Jan 31. PMID: 21282661; PMCID: PMC3041121.
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