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Why Don’t We Know How Periods Affect Exercise?

Photo-Illustration: by The Cut; Photo: Getty Images

“Hot Bod” is an exploration of fitness culture and its adjacent oddities.

Never once, not in my 15 years of monthly bleeding, did it occur to me that a physical process like menstruation might be linked to literally anything else happening in my body. Then, a few months ago, an authoritative and intimidatingly fit friend mentioned feeling a surge of energy while lifting weights, and attributed this to a phase in her menstrual cycle. Well, well, well! Here was a revelation. How could I have missed this relationship between periods and exercise, I wondered, and was it just because of a boring, old-timey sexist taboo? But also: What’s actually the relationship here? The hunt for answers began. If my period influenced my abilities, energy, or feelings around exercise, I needed to know exactly how.

As I would with anything related to the bodily experience, I went looking for some rigorous, scientific research about this connection. But unfortunately — and unsurprisingly — there really isn’t any. We could live in a time when there’s ample, extensive research — clinical trials and observational studies with longitudinal scope — to consult as reference points for the physical experiences associated with menstruation cycles. We don’t live in that time. Not only do we not know much at all about menstruation, but just 4 percent of sports-science research has exclusively focused on female participants. The doctors, clinicians, and researchers I spoke to confirmed that there’s a gaping lack of scientific information concerning the interaction of menstruation and physical activity.

And the way that many clinical professionals treat menstruation communicates that periods are still a taboo, rather than a regular bodily process. “Doctors only ask ‘When was your last period,’ in order to determine pregnancy,” says Lynette Medley, who co-founded SPOT Period, a community center in Philadelphia that provides menstruation supplies as well as health education. “They don’t ask, ‘How was your menstrual cycle? Did it impede anything in your day?’” Meaningful interrogation of your physical experience feels good, says Medley, “and if it makes you feel good, then you can move in a comfortable manner.”

I can confirm: Interrogating my physical experience feels not only good, but fun. My foray into these semi-mystical theories about menstruation over the last several months reminded me a little of learning about astrology: It’s fascinating because it’s all about me and my little minor fluctuations. The theories thread my life with new explanations — if I’m sleepy, I can just credit a phase in the cycle. If I’m restless and antsy? That’s also a phase in my cycle. The woo-fitness realm also provided a new lens for my relationship to the world, and new lenses always reinvigorate going about my everyday life.

Turns out I’m in good company: all sorts of people — professional athletes, my old roommate, casual exercises — use menstrual cycles to inform their physical pursuits. I learn that the World Cup–winning 2019 U.S. Women’s Soccer team structured training around their cycles; and I keep hearing about WILD AI, an app for serious athletic training that foregrounds menstruation. Last month, The Class launched a cycle-awareness program to optimize movement in sync with a period flow. “Because it’s an under-researched area, the best research we’re going to get is on our own bodies,” says Tia Spowart, who’s orchestrating the series. “Exploration is such a powerful thing.” Spowart started working with a cycle coach in February; she has premature ovarian failure and doesn’t have a cycle. These sessions, she says, “gave my body a sense of rhythm.” Flow, no flow, outrageously irregular flow: Spowart recommends cycle awareness practice for everyone as a way to examine the balance of physical energy and rest.

This menstrual calendar employed by The Class has a seasonal poetry to it, with a light touch of goddess intuition. There’s a bounding, overenthusiastic spring phase (follicular) marked by excess enthusiasm. There’s also a phase for social physical activity, a phase for expressive and impulsive movement, and a phase for restoration. The movement program changes every week in accordance with your cycle phase, which is great for my impatient brain, but also wise for my ambitious brain. “There’s a lot of pressure to always be high-functioning while working out,” says Spowart. “This just shifts that narrative and conversation to really practice deep listening with your body.”

The Class harnesses the phase principles outlined in a book Spowart says is newly cultish with the cycle-syncing set: Miranda Gray’s The Optimized Woman (2009). The book’s wild claims about shifting physical powers are so fun and I think about them constantly. For example, during the “expressive phrase” (ovulation, baby) you should dance and have fun with your body. Cool. And in “the creative phase” (PMS) one should play sports because of lightning reflexes and “intuitive coordination”! And then, sincerely, news I could use: During the arrival of the period, don’t override your restful impulses. “Mentally forcing ourselves to be more active in this phase often generates anger, frustration, and stress,” Gray writes. This book, of course, manages to never mention bleeding or blood once. “Let me know if they mention trans people,” my partner said, and I didn’t have to bother them the whole time I was reading it.

Of course, my period mysticism is reactionary; it’s standing in the void where rich medical, scientific information about menstrual cycles and physical activity should be. This neglect has denied people who menstruate a wealth of potential knowledge. But things are starting to shift. In March of this year, the Apple Women’s Health Study team at Harvard’s T.H. Chan School of Public Health released preliminary scientific data on menstrual symptoms of over 10,000 participants, the first study of its kind. Dr. Shruthi Mahalingaiah, one of the study’s principal investigators, tells me that this study will replace a historical lack with information to optimize health for menstruators, writ large. “More knowledge will not only impact gynecologic decisions, but overall health,” she says. And Mahalingaiah says that we’re on a precipice of finally getting some good scientific information. “There’s just an explosion of different kinds of tracking that put us on the cusp of learning a lot about ourselves as individuals and kind of population level trends,” she says. “It will be really interesting to really understand how the phases of the menstrual cycle might underlie patterns of sports and activity.”

The importance of the relationship between menstruation and movement “is starting to take hold in the areas of science and medicine that matter,” says Dr. Stacy Sims, a researcher and nutrition scientist at Auckland University of Technology focused on female physiology. “One of my Ph.D. students is studying ACL rehabilitation based on the menstrual cycle phases and another is doing sex difference in concussions,” Sims says of two studies that will contribute to the clinical conversation.

We can hope for some meaningful information— maybe even in the next year! — say the researchers I speak with, and we can hope that this deserved attention will flow steadily after that, forever and ever, amen, but in the meantime: Woo has some distracting, energizing, and very fun theories for us while we wait.

Why Don’t We Know How Periods Affect Exercise?