Cycle Syncing: Can Aligning Your Workouts With Your Menstrual Cycle Make You Fitter?

If you have periods, you’ve probably noticed the effects your hormones can have on your workouts. It can certainly be tough to get through a long run when you’re fatigued. The same goes for mustering the motivation to stick with an intense strength workout when you’re battling a bad case of cramps.

Instead of just pushing through, is it better to let your hormones call the shots? Some “fitfluencers” and trainers say yes, you should adjust your training to your menstrual cycle.

The concept, known as cycle syncing, was popularized in part by Alisa Vitti, a researcher and holistic health coach who founded the female hormone company Flo Living in 2001. Vitti also developed the Cycle Syncing Method, a personalized health plan that matches your diet, workouts, sleep, and lifestyle with your cycle phases to help you reach your health goals.

Cycle syncing (#cyclesyncing) has racked up 499.5 million views on TikTok, while cycle syncing workouts (#cyclesyncingworkouts) currently has 42.7 million views. The idea is that planning your workouts around four stages of the menstrual cycle helps optimize your fitness results.

But what does the science say?

Is There Evidence That Cycle Syncing Workouts Really Work?

Estrogen and progesterone are the two primary female reproductive hormones that fluctuate throughout the body to help prepare the body for a potential pregnancy.

But these hormones play helpful roles in many bodily functions and organs besides those associated with reproduction, including those that influence exercise and recovery. A few include the cardiovascular system, bone formation, and muscle contraction, per research published in Medicine & Science in Sports & Exercise in October 2022.

“There’s some evidence, primarily in animal models, that suggests estrogen is beneficial for strength,” says the researcher Rita Deering, DPT, PhD, an assistant professor of physical therapy and the director of the Movement Sciences Laboratory at Carroll University in Waukesha, Wisconsin.

According to a review published in Bone in June 2019, estrogen helps maintain muscle mass by promoting muscle protein synthesis, or the process of creating new muscle protein. In fact, lower estrogen levels are thought to have a hand in the dramatic strength and muscle losses that occur after menopause, per the same review.

Moreover, it’s believed that there are times during the cycle when high-intensity activities can even be riskier. “There are studies that show that different levels of estrogen or progesterone can influence how lax your ligaments are, which may put you at risk for ligament injury,” says Miho J. Tanaka, MD, PhD, an orthopedic surgeon, researcher, and the co-leader of the Mass General Brigham Women’s Sports Medicine Program in Boston.

Research suggests, for instance, that female athletes may be less likely to tear the anterior cruciate ligament (ACL) in their knee during the luteal phase and more likely during the follicular and ovulation phases of their menstrual cycles (per two different studies — one published in 2006 in the American Journal of Sports Medicine and one published in the same journal in 2002), when the ligament may be looser and more likely to overstretch.

The follicular phase starts when you get your period and ends with ovulation around day 14. Ovulation is when one of your ovaries releases an egg.

But, Dr. Tanaka says, “a lot of the studies are really small [when it comes to the number of people followed], and even when we put them together, it’s not enough to say we have to make changes to our workouts.”

Similarly, a review of 78 studies published in 2020 in Sports Medicine found that strength and endurance exercise performance might suffer during the follicular phase of the menstrual cycle. But the effect was considered trivial, and the quality of the studies included in the review was classified as “low.”

So, it’s possible that the changes in hormones at different phases of the menstrual cycle affect your body in ways that limit or boost exercise performance. But the research isn’t strong or consistent enough to tell one way or the other.

What the Research Doesn’t Say About How Our Periods Affect Exercise

After reviewing 62 studies published between 1970 and 2021, the authors of a scoping review published in April 2023 in Women in Sport and Physical Activity Journal concluded that, while cycle-related hormones may influence performance, most of our assumptions about how they work are based on animal and test-tube studies. In other words, we need more research that looks at people who menstruate.

Unfortunately, the menstrual cycle complicates the research process and eats up budget money — something not many scientists choose to deal with.

Because of the unknown impact and effects of hormones and the menstrual cycle, many studies on exercise performance and injuries intentionally exclude people with periods, says Madhusmita Misra, MD, MPH, a pediatric endocrinologist and the chief of the division of pediatric endocrinology at Massachusetts General Hospital for Children in Boston. “This has resulted in a further dearth of information in female athletes.” (A study published in 2021 in Women in Sport and Physical Activity Journal found that 31 percent of sports and exercise science research focused on males, 63 percent included males and females, and only 6 percent included females only.)

As Dr. Misra explains, it can be challenging to recruit study participants who are at similar phases of the menstrual cycle. And given how much menstrual cycles can vary from person to person — even from month to month in individuals — it can be tough to predict what each participant’s cycle will look like over the course of the study.

“Unless you study everybody at a specific cycle phase, like the follicular phase, you don’t really have a comparison to say the impact of exercise is different during other menstrual phases,” Misra notes.

As the topic keeps attracting attention, Tanaka hopes it will spur people to do more research. “The more we can get people to realize that this is an underserved and under-researched area, the better we can change that over the next 5 to 10 years,” she says.

How Should You Work Out During Your Cycle?

While there isn't yet research to suggest that someone will benefit from syncing their workout with their cycle, there may be a more practical reason to switch up your exercise during the month: your symptoms.

For example, if you feel sluggish during your period, you may want to plan something that’s lower intensity than usual (such as a walk instead of a long run). Racked with painful cramps? A gentle yoga or stretching session might help alleviate them. The key is to listen to your body and do whatever you can manage with your symptoms.

As Deering explains, an individualized approach is better than following a clearly defined schedule every cycle. “Your symptoms could be completely different this month compared to the next,” she says. “Maybe you don’t need to modify [your workouts] this month because your symptoms are relatively mild, but next month, if it really knocks you for a loop, you might have to modify your [workout] intensity.”

In a study published in October 2022 in Medicine & Science in Sports & Exercise, 40 menstruating women underwent a series of physical performance tests at different phases of their cycle. The results show that the women’s performance outcomes were not linked to fluctuations in sex hormone levels, but mental, emotional, and physical factors like motivation, enjoyment, pain, and the woman’s perception of how well she did on the performance tests (which varied throughout the menstrual cycle) did have an effect on performance measures.

The researchers concluded therefore that one’s menstrual cycle does affect physical performance when it comes to exercise, but that those effects aren’t consistently linked to changes in hormone levels.

The bottom line: Research has not yet demonstrated how the menstrual cycle affects workout performance. But if there’s a monthly workout schedule that feels good for your body (whether it’s aligned with your period cycle or not) and it’s safe and appropriate for you, experts say listening to your body in that way is indeed worthwhile.