Can “cycle syncing” really help your exercise performance?

If you are a menstruating woman, you have likely noticed changes in your energy based on where you are in your cycle. Whether you are currently on your period, about to ovulate or in the luteal phase, chances are, you have noticed a difference in your energy and even motivation to exercise at different times throughout the month. But, does changing your workout routine based on your cycle really improve your physical performance? What does that data really tell us? 


Let’s dive in!


First off, let’s talk about the term “cycle syncing”. 

Cycle syncing is the idea that changing the type of physical activity or exercise you do throughout the month not only can impact but may also optimize your physical performance. In other words, if you were an athlete, is your ability to perform dependent on where you are in your menstrual cycle? The theory of cycle syncing has also grown in popularity among online influencers. Many will preach that changing your workouts throughout your cycle can improve your physical performance and should be something we should be considering for all women who are menstruating. 


So, what does the research really tell us? 


Now, although you may not consider yourself an athlete or “well trained”, when looking at the latest research on physical performance and menstruation, it is important to know that many researchers define “well trained “as those who exercise 4 times per week or more. So although you might not be competing as an ultra-marathoner or qualifying for the olympics, if you exercise four times a week or more, you would likely be considered “well trained” by researchers. This is extremely important to mention because often when evaluating the latest research on peak performance, many women may not think the latest research applies to them, when in fact, it does. 


We also have to consider the quality of current available research and appreciate both its strengths but also potential pitfalls. One of the biggest pitfalls of the current available data on physical performance and menstruation is that there is still relatively limited research currently available and of the research that is available, many of the studies are done on a small population of women making it even harder to distinguish statistically significance. This not only should be a limiting factor we need to consider when reviewing such research but, it also points to the fact that this popular topic is in need of even more attention by researchers. 

So let’s talk about some of the latest research on physical performance changes across menstrual cycle phases. Although new research is currently evolving, let's talk one particular 2020 systematic review and meta-analysis. 


In this meta-analysis, researchers reviewed the variations in strength related measure during the menstrual cycle in eumenorrheic women. In other words, they were evaluating strength measures in women with otherwise normal or regular menstrual cycles. This meta-analysis included 21 studies. Now although this might sound like a large review, there were actually only a total of 232 participants involved throughout the studies. 


Does this mean this meta- analysis is invalid? 




However, it is something worth mentioning and is something I often consider when evaluating the latest research and how to apply it in our clinical practice with patients. The other issue I had with this particular analysis was that they didn’t set a standard for the level of training involved in the analysis. Four of the studies involved sedentary women, while six studies used recreational/active participants, five of the studies used moderately training participants and three of the studies used highly trained athletes. They also included two studies that didn’t even mention the level of training by which their participants were selected. So as you can see, the level of training may have also impacted the results provided by the meta-analysis. 


In this particular analysis, researchers looked at the “early follicular phase” which they defined as less than or equal to five days from the onset of menstruation (aka your period) vs. the ovulatory phase, which they defined as +/- 2 days from ovulation. They also compared the early follicular  phase to the mid-luteal phase, which they defined as +/- 2 days from the onset of menstruation or 7 days +/- 2 days from ovulation. 


Unfortunately, even though this analysis may sound straightforward in terms of the phases in which researchers evaluated strength performance, the way in which each study evaluated for ovulation varied. Some researchers used ovulation predictor kits and LH surges to define and determine ovulation while others used other measures, including saliva hormone testing, which we know also has its inaccuracies. 


Now, the reason I want to mention some of these important pitfalls in the latest research is because sometimes when patients ask us questions like “should I do yoga during the luteal phase and sign up for a HIIT class in the follicular phase? My answer may not be as black and white as you may want. The reality is, there is still so much we need to investigate in terms of application of the latest research, especially in women’s health. 


We also need to advocate for more research to be performed on females only.  Too often, researchers like to assume that their results that involve mostly male participants would result in the exact same patterns when applied to women. And ,as you obviously can attest to, women and men are VERY different and we aren’t similar “little men”. This is why when evaluating the latest health and wellness trends, it’s important we first evaluate if some, or any. of the research currently available was actually done on women. 


A great example of this lack of research is when we discuss intermittent fasting. I get asked all the time, especially by women with PCOS, if they should undergo intermittent fasting regimens in order to lose weight during their fertility journey. The reality is, we have VERY limited, if any, research to show us the benefits of intermittent fasting on women, let alone women with PCOS who are trying to conceive.  


Now I know this might sound disheartening but it's important to mention the limits of currently available research because although social media influencers like to make you think that you are simply not doing the “one thing” they are promoting that will magically change your health, it’s important when we create strategic plans for our patients, that we use and interpret the current available research. Sometimes, this may involve telling patients that there is no evidence backing up their restrictive diets, their fancy new supplement they ordered online or that exercise routine they just started. 


Naturopathic medicine is an extremely powerful tool, especially for women trying to conceive, however, I think it is equally as important to mention the limitation we currently have in research. The same is true for conventional medicine. Sometimes the research we currently have is limited and it’s okay to say “we don’t know” or “there isn’t research to support XY or Z”. 


Now in terms of physical performance changes across menstrual cycle phases, the reality is based on current research, there is very limited evidence that physical performance is significantly impacted by your menstrual cycle phase. 


So what does this mean for you? 


What this means, in terms of applications, is that researchers do not currently see a major impact on physical performance based on your menstrual cycle phase. So whether you decide to jump into that HIIT workout or start that restorative yoga practice, the type of exercise you choose shouldn’t be based on where you are on your menstrual cycle. 


“But, why would I notice changes in my energy and “performance” throughout my menstrual cycle, Dr. Zen?” 


Researchers believe that there are likely other factors involved in hormonal changes that may influence your interpretation of exercise and physical performance. Some of these changes can include mood, sleep and even dietary changes. 


So yes, if you are on your period and you are eating more sweets and less nutrient dense foods, chances are you likely might be “under-fueling” and may notice a dramatic difference in your performance in that HIIT workout class that you just signed up for.

Now this doesn’t mean we shouldn’t listen to our body but it does mean that we actually shouldn’t “blame” our menstrual cycle for changes in our physical performance. Instead, we should be mindful of the other factors including mood, sleep and dietary changes in order to help support our energy and motivation involved in our exercise routine and peak performance.

Blagrove RC, Bruinvels G, Pedlar CR. Variations in Strength-Related Measures During the Menstrual Cycle in Eumenorrheic Women: A Systematic Review and Meta-Analysis. J Sci Med Sport. 2020;23(12):1220–7.


About the Author: Meet Dr. ZenAlissia Zenhausern- Pfeiffer, NMD, FABNE, (commonly known by her patients as Dr. Zen), is a licensed naturopathic doctor board certified in naturopathic endocrinology and the founder of NMD Wellness of Scottsdale, a premier naturopathic medical practice that focuses on helping women to take a proactive approach to their hormone and fertility health. Dr. Zen has been featured as a lead expert in Forbes, Shape Magazine, and Instyle and is deeply passionate about bridging the gap between traditional and natural medicine in the world of fertility. She works with a variety of hormone related issues including PCOS, endometriosis and unexplained infertility. Her goal is to help more women get back into the driver’s seat of their own health to make lasting transformational changes to their health to bring more cute and adorable babies into this world. Read More About Dr. Zen...