There’s a wealth of information out there about the menstrual cycle (MC) and hormones, which is fantastic! However, just because information is available doesn’t always mean it’s accurate or applies to everyone. This is especially true when discussing the menstrual cycle, where there's significant variation from one individual to another.
What’s exciting about the growing research on this topic—and on female athletes in general—is that it allows us to challenge our preconceived beliefs and biases. We can re-examine what we think is true and re-evaluate how we should approach training.
A hot topic that keeps resurfacing is the idea of adjusting (or periodizing) training based on the phases of the menstrual cycle, known as phase-based training or cycle syncing. It’s based on the premise that sex hormones impact a female's ability to build muscle, exert force, and recover from training. Many well-intentioned professionals may be trying to implement this concept to support female athletes. However, here’s the issue: the evidence for this approach just isn’t there yet. We need to critically evaluate what we’re actually trying to achieve.
I would argue that maybe we are asking the wrong question. Maybe the focus shouldn’t be on periodizing training around the menstrual cycle, but rather: How can we help athletes who experience symptoms during their menstrual cycle feel better so they can continue training, playing, and performing consistently?
Let me explain why:
1. The Evidence is Missing or Conflicting
Periodizing based on the menstrual cycle is based on the idea that sex hormones influence a female's ability to gain muscle (muscle hypertrophy) and generate power/speed. The theory suggests that during the follicular phase, when estrogen is high, muscle building and power generation are enhanced (1). Conversely, during the luteal phase, when estrogen is lower and progesterone is higher, we are more catabolic—meaning more prone to breaking down muscle (1). While this may be true to some extent, estrogen and progesterone aren’t the only hormones affecting muscle hypertrophy and performance (1).
More importantly, the evidence on whether hormone fluctuations truly impact physical performance is highly conflicting. Some studies suggest it does, while others say it doesn’t. This is largely a result of low-quality research studies, as well as a lack of consistency in how to track and evaluate the different MC phases (1). Without conclusive data, we can’t confidently say that periodizing training around the menstrual cycle is necessary or beneficial. We also need to consider any potential downsides to phase-based training. Could we be underloading/undertraining athletes? For example, if you reduce the load during the luteal phase, which can vary from 13 to 25 days depending on the individual’s MC length and time of ovulation, you could be undertraining for two weeks every month. Researchers also argue that if hormone fluctuations are truly impacting physical performance, it’s typically only for a couple of days each cycle, not throughout the entire luteal phase (1).
This approach could be right for some individuals, but based on the evidence, it’s not something we should be applying broadly to all female athletes, particularly in the absence of symptoms and for athletes on hormonal contraceptives (1).
2. Athlete Symptoms Impact Performance
What we do know is that how an athlete feels affects their performance (2). Many athletes have a perceived decrease in performance during the late luteal/menstrual phase (2). During this part of the MC, an inflammatory response is triggered by the drop in hormones, causing symptoms such as bloating, cramps, fatigue, etc. (PMS), and these symptoms can impact an athlete's ability to train and perform (2). Athletes can also be preoccupied with worrying about leaking while having their period (2).
That’s where the focus needs to be—on helping athletes manage these symptoms so they can continue training and performing consistently. This requires an individualized approach, as every athlete’s experience with their cycle is different. For some athletes, adjusting training load and volume during this time of their MC could be helpful, but there are also other areas of their health that can be addressed that may have more benefit. It’s highly individual.
3. Hormonal Contraceptives Change the Picture
If an athlete is using hormonal contraceptives (birth control), periodizing training doesn’t really apply since their hormone fluctuations are different from those with a natural cycle. Athletes on birth control do not ovulate and do not have a period—they have a withdrawal bleed (3). Typically, hormones are kept stable throughout the cycle (3). This is another reason why a one-size-fits-all approach won’t work.
So, What’s the Goal of Periodizing Around the Menstrual Cycle?
When adjusting training to the phases of the menstrual cycle, it’s important to ask: What’s the goal? Are we trying to improve performance? Improve health? Reduce injuries? Hormones like testosterone, estrogen, and progesterone are just one part of the picture (1). Other factors, typically ones related to the gender experience in sports—such as access to proper training, proper nutrition, the sport and training environment, and overcoming misconceptions about female athletes and strength training, just to name a few—also play significant roles in performance and injury risk (4).
We currently lack the data to support periodizing based on the menstrual cycle as a strategy for all female athletes, for reducing injury risk, improving performance, or increasing strength. There could be potential negative consequences, such as undertraining athletes. We just don’t know yet. We will get more information as research continues to evolve in this area. Regardless, it is a complex topic that is highly individual and multifaceted. We can’t ignore the gender experience of athletes as it relates to injuries and performance. Although important, there’s more to the picture than just sex hormones (1).
Shifting the Focus
What can we do to help female athletes feel better throughout their cycle so they can keep training and performing? This is where I like to start with athletes I work with. This requires an individualized approach.
The research does confirm that hormonal fluctuations can cause symptoms like fatigue, bloating, and mood changes, which can affect training (2) (which obviously as a female athlete you know this 🙂). So, the focus should be on managing these symptoms to keep athletes feeling their best—allowing them to maintain consistency in their training and performance.
By reframing the question, we can better support female athletes in achieving their full potential.
This is just the start of the conversation. Stay tuned for Part 2, where I lay out in detail what a normal and healthy menstrual cycle is, and Part 3, where I will try to convince you why you need to understand your MC as an athlete and how this can improve your performance.
Don’t get any of this information wrong: your menstrual cycle is a vital sign and is important (5), but we equally need to understand it to make the best choices for ourselves, in our health, and in sport performance.
References:
Van Every DW, D'Souza AC, Phillips SM. Hormones, Hypertrophy, and Hype: An Evidence-Guided Primer on Endogenous Endocrine Influences on Exercise-Induced Muscle Hypertrophy. Exerc Sport Sci Rev. 2024 Oct 1;52(4):117-125. doi: 10.1249/JES.0000000000000346. Epub 2024 Aug 1. PMID: 39190607; PMCID: PMC11460760.
Bruinvels G, Goldsmith E, Blagrove R, et al. Prevalence and frequency of menstrual cycle symptoms are associated with availability to train and compete: a study of 6812 exercising women recruited using the Strava exercise app. British Journal of Sports Medicine. 2021;55:438-443.
Briden, Lara. The Period Repair Manual. Greenpeak Publishing, July 2018.
Parsons JL, Coen SE, Bekker S. Anterior cruciate ligament injury: towards a gendered environmental approach. British Journal of Sports Medicine. 2021;55:984-990.
Menstruation in girls and adolescents: Using the menstrual cycle as a vital sign. (2018). Pediatric Clinical Practice Guidelines & Policies, 1319–1319. https://doi.org/
Comments