Cycle Syncing Won’t Fix Women’s Fitness

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While most of the video series and programs available on the popular “holistic wellness”/fitness site Alo Moves—owned by the trendy activewear line Alo Yoga—are run by solitary instructors, the company’s newest offering is marked by photos and videos of a group of four women pulled close up against one another and roaming Hawaiian beaches.

It’s a clearly symbolic presentation of the company’s new SYNCD program, a collection of 24 videos designed to guide users through self-care and fitness activities customized for each of the four phases of the menstrual cycle. The program, which launched in late August, is the latest—and likely not the last—in a wave of offerings from fitness and wellness purveyors looking to latch onto the recent popularity of a workout method known as “cycle syncing.” Unlike the push-through-the-pain approach of training during menstruation women athletes have adopted for decades, cycle syncing invites those same people to instead allow their exercise—and often, other lifestyle elements—to be dictated by not only their periods, but their entire menstrual cycles. The four instructors leading SYNCD’s classes, Alo Moves says, are all enthusiastic practitioners of the strategy.

Cycle syncing is one of the biggest topics in women’s health right now. Since the release of a Nike cycle-syncing program via their Training Club app in 2022, Google searches for the term have more than tripled. The last six months have seen an explosion of at-home programs and apps, including offerings from big players like the period-tracking app Flo, the activity-tracker WHOOP, and the at-home fitness company Tonal. On TikTok and Instagram, some personal fitness creators offer their own plans online for a fee, designed for followers to use alongside a period-tracking app. If your own favorite lifestyle or exercise brand doesn’t yet encourage cycle syncing, chances are high that they’ve got something in the works.

In theory, such an approach sounds like a welcome change, given that women have historically been excluded from sports science; in practice, experts say that these programs can be overly generous in their interpretations of a limited amount of research about the physical and emotional effects of the menstrual cycle. Where content creators and the companies behind new programs say cycle syncing can help people better attune to their bodies, critics worry that the technique could promote a harmfully reductive and narrow vision of how the menstruating body works. The specificity of these programs simply can’t apply to everyone, says Tory Eisenlohr-Moul, a clinical psychiatrist at the University of Illinois at Chicago. “Given what we know about how differently people react to the cycle … you’re contributing to this misogynist idea that all females are driven by their hormones.”

Hormones throughout the cycle

Cycle syncing taps into the wellness world’s current obsession with hormones, the chemical messengers that drive key physiological functions of the body. A central idea promoted by the fitness and nutrition influencers who first made cycle syncing popular online is the idea that a healthy body is one in which unspecified hormones are “balanced.” Their goal is to regulate the body’s regulators, which in a healthy person fluctuate as needed in order to do things like maintain your core temperature and put you to sleep after a long day.

Unlike hormone balancing efforts, however, cycle syncing is about indulging, rather than controlling, the natural ebbs and flows of certain hormones. The menstrual cycle is operated by specific hormones, like follicle-stimulating and luteinizing hormones, and causes near-constant fluctuations in others, including estrogen, progesterone, and testosterone. We know a lot about what these patterns look like and some of their more standard effects on the body that appear throughout the four phases of a cycle. During the late luteal phase, for instance, which occurs just before menstruation, progesterone plummets, which can have a destabilizing effect on mood. In serious cases, this is recognized as premenstrual dysphoric disorder (PMDD), but nearly anyone who’s been a teenage girl or lived with one has experienced some of progesterone’s mental effects. Similarly well-documented peaks and valleys in libido, thermoregulation, skin health, and taste perception, are all possible, but vary from person to person. While different syncing apps have different approaches—some are more geared for exercise fanatics, others have a more New Age vibe—they’re all pretty much the same when stripped down to their fitness plans. During the menstrual cycle, suggested exercises are simple activities along the lines of gentle yoga and pilates, though Nike suggests high-intensity interval training, or HIIT, for those who have the energy. HIIT tends to be recommended for the follicular phase, which occurs for roughly a week and a half following menstruation, when users are told to expect abundances of speed, power, and creativity. The much-shorter ovulatory phase is similarly high-octane, while in the luteal phase users are encouraged to embrace the natural energy letdown by focusing on flexibility exercises and other low-impact movement. “Based on my experiences, and my knowledge about anatomy, and physiology, and the menstrual cycle, I think there’s some merit to it,” says Amy Tremback-Ball, a professor of physical therapy at Misericordia University who’s studied the menstrual cycle’s effect on college athletes. “For those who might be training for something and knowing that they’re going to push—like bumping up two miles or four miles in a run—I think there is a better time to do that to avoid injury.” Tremback-Ball, formerly an ultramarathoner, says that her most serious running injuries occurred during her luteal phase, when connective tissue can weaken. However, none of the programs address the unique hormonal landscapes of the growing number of people who use any form of hormonal birth control, including pills, patches, and IUDs, as well as those who are pregnant, menopausal, suffering from endocrinological disorders, or using any sort of hormone therapy. While future products may address these populations, for now cycle-syncing apps remain exclusively focused on those with unaltered menstruation.

What does the research say?

Cycle-syncing programs frequently claim they’re designed using the latest research on athletic performance throughout the cycle, but often neglect to mention that just about all of that research has been done on elite female athletes, who aren’t representative of the typical customer of these programs. What’s more, the research is still less than a decade old, and the flurry of preliminary studies in recent years are still raising more questions than they answer. Among their findings include the possibility that building muscle could be easier during certain parts of the cycle and that there is a connection between the higher rates of orthopedic injuries in female athletes and looser, more injury-prone joints during the ovulatory phase, when the body is prepared for potential implantation. They’re groundbreaking findings, but it could be years before any universal real-world application materializes.

The preliminary studies most relied on by cycle-syncing programs are survey-based, and reiterate what people who menstruate have so often been told to ignore—that it can suck to exercise on your period. Researchers asking menstruating athletes including professional rugby and soccer players to report the effects of their cycle have all found that over 90% of respondents cite the menstrual phase as a time when they’re lower energy or feel less physically and mentally powerful. It’s the underlying, less-technical message of these types of studies—that the body can no longer simply be ignored—that cycle-syncing programs have latched onto.

Menstruation is just one piece of the puzzle

Eisenlohr-Moul, who studies menstrual hormones in the brain, says cycle-syncing programs seem to be predicated on the assumption that menstrual hormones are the most powerful forces in determining your mood and energy at any given moment. But it ignores the multitude of other physiological and mental factors that play a role in how someone feels. “Exercise is so much about the brain and your ability to make yourself do things that are sometimes physically uncomfortable,” she says. For those without PMDD and similar serious hormonal problems, factors like how much stress they’re under at work or how many hours they slept the night before can easily overshadow cyclical changes in mood or energy.

Be aware, too, Eisenlohr-Moul says, of what any new fitness program may be asking of you outside the gym. Alo Moves’s SYNCD includes not just workouts and meditation sessions, but guidance on making a turmeric tea for ovulatory pain and dry brushing the skin to promote general detoxification and decrease water retention. Though they may have value as enjoyable rituals, neither of these practices are backed by empirical evidence. They’re easy to skip, but “if you’re a person who kind of tends to spiral into a compulsive place with those kind of rules, then you might want to back off,” says Eisenlohr-Moul.

Tremback-Ball and Eisenlohr-Moul agree that cycle syncing should be viewed as more of a learning experience than a strict regimen, simply because the variety in how individuals experience their menstrual cycles can’t possibly be captured by a single program. In an ideal world, says Tremback-Ball, everyone who wanted to learn about cycle syncing for their own body would have an informed coach to help them develop an individualized program.

Eisenlohr-Moul recommends trying a program for a month or two if you’re interested, and to pay close attention to whether or not it actually makes you feel any better, or if it’s taking more effort than it’s worth.

“If your workout is not making you happy because it’s being dictated by something,” says Tremback-Ball, throw it out and “do what makes you happy.” Your hormones will be just fine.