Menstruation Ain't an (Evidence-Based) Excuse. Period.
I'll be the first to admit when I'm wrong, or when I've changed my perspective on an issue on the basis of newer, better, or higher quality research.
Not only that -- but when it comes to an opinion I've held that can profoundly affect my clients' behaviour and success, as a women's health professional it is my duty to do that.
So first, let's start with the past:
I've previously cited, both in talks and online, a 2022 study that concludes there are meaningful differences in training and performance during the follicular and luteal phases of the menstrual cycle, and that women might want to time their workouts around their menstrual cycles to maximise performance and just feel better overall.
Problem is - this particular "study" was really just a discussion paper - not an individual study or RCT - and one of the main studies it was based on, from 2014, was only done with an N=20 and compared outcomes on only a single exercise (isometric leg press).
In fact, a truly comprehensive meta-analysis done in 2020 that included over 50 studies with an overall N of thousands and exercises ranging from cardio to CrossFit showed "trivial," low-quality support for the differences in menstrual phase-specific training outcomes.
And if we're gettin' serious-serious, a 2003 study concluded that "regularly menstruating female athletes, competing in strength-specific sports and intense anaerobic/aerobic sports, do not need to adjust for menstrual cycle phase to maximise performance," a 2019 study noted that "force, velocity and power output [on Smith machine squats] were very similar in all menstrual cycle phases," and a throwback 1999 study suggested that for 30-minute bouts of moderate-intensity exercise, "menstrual cycle phase has minimal influence on any exercise responses."
So what the hell, right?
Why are we being told that we can't or shouldn't perform during certain phases of our cycle - or getting in our own heads about whether we're performing a certain way on a certain day due to the effects of our period - when science is consistently telling us it's just not true?
This is where I really want to start to redefine the conversation, as someone responsible for coaching and communicating with over 100 female clients per week.
I can't tell you how often I get a note on my coaching platform that says something like, "PMS is killing me...sorry couldn't exercise today!" or "on day two of my period, can't lift weights" or "was going to head out for a run, but then my period started." There is definitely some level of understanding among women - even very fit women! - that having or expecting a period is an unquestioned, no-explanations-needed reason not to exercise.
And I want to push more on why that is.
To some extent, there is absolute, individual and qualitative personal evidence as to why you might choose not to work out during or immediately before your menstrual cycle - you feel tired, you're nervous about leaking/protection during sport, cramps are raging, or you're just in a piss-poor mood. I get those; I do - and like I said, whether to exercise is absolutely your empowered choice to make, period or not.
But I do want to emphasise on the counterpoint that eumenorrheic women (aka women who are menstruating normally; this diatribe excludes women with severe period problems like endometriosis) are going to get 13 periods per year, lasting for 4-7 days on average, so if you're skipping out on exercise every cycle, that's 52-91 days - about 2-3 months (!) - of missed activity annually.
Much like during pregnancy, when massive hormonal changes are inescapable and their effects on physiology very very real, I will offer the same advice to healthy, menstruating women as I do to my prenatal athletes:
As in pregnancy, where fit expecting women can't afford a 40-week break from exercise - fit nonpregnant women looking to build lean muscle and maintain high performance really can't afford a 9-week (the cumulative average of annual cycle days per year) hiatus, either. So:
Do. Something. Do the best you can. Even if you gotta peel yourself into a vertical position to take a stroll around the block or put on a 10-minute YouTube yoga, do it. Listen to your body and moderate or modify as necessary, but know that maintaining your regular movement routine to whatever extent possible is not only doable - it's actually helpful.
And you wanna know what the science says on that, by the way?
Five RCTs (highest quality evidence) with an N of nearly 500 concluded that "aerobic exercise is effective in improving physical physiological symptoms among women with premenstrual syndrome (PMS)," another 2022 study out of Japan showed that "young women with high physical activity had milder physical and psychological symptoms of PMS than women with lower physical activity," and the most recent study on the issue claims that "physical exercise is nearly a new non-medical intervention to relieve [period] associated pain...aerobics, stretching and resistive exercises for 8-12 weeks, either supervised or unsupervised, relieves pain."
The takeaway is this, gals: if your periods are normal, there's no need to adjust your workout schedule, type, or timing to work around your menstrual cycle. Sure, you may feel a bit better or worse, physically and mentally, during certain times of the month (just as we would after a poor night's sleep versus a great one, or during a stressful time during a calmer one, etc.) - but that's no reason to put exercise on the back burner or worse, skip it entirely just because Auntie Flo came a-knockin'.
Lace up your shoes, take a deep breath, and move. You'll be glad you did.