Cycle syncing, or aligning certain exercises or dietary changes to the different phases of your menstrual cycle, has exploded in popularity in recent years. Social media influencers claim the trend has helped them in various ways, including building muscle.

But a new study, recently published in The Journal of Physiology, found that coordinating workouts, like pilates or strength training, to phases of your cycle is likely not all that effective for packing on muscle.

The study was small, with only a dozen participants. Still, it provides new insight into a topic that’s been little studied, according to Hugh Taylor, MD, the chair of Obstetrics, Gynecology & Reproductive Sciences at Yale New Haven Hospital.

The findings reinforce what doctors have suspected—that “hormones do not dictate strength gains,” Amy Banulis, MD, an OB/GYN at Kaiser Permanente in the Washington, D.C. area, told Health.

Lauren Colenso-Semple, the study’s lead researcher and a doctoral candidate at McMaster University, said she was interested in exploring the physiological effects of cycling syncing for two reasons. 

First, scientists know so much about male sex hormones, such as testosterone, and their effects on muscle mass—but the influence of female sex hormones is poorly understood.

Second, some exercise and nutrition researchers have historically hesitated to include women in studies due to concerns that female hormonal fluctuations could impact the findings. 

So, to better understand whether cycle syncing works, Colenso-Semple and her team of researchers recruited 12 healthy females between the ages of 18 and 30 who had regular periods and hadn’t used hormonal contraception in the past six months. Each participant completed a full-body scan at the start of the study to assess their body composition.

The women then participated in two phases of the study: one during the late follicular phase, the time before ovulation when estrogen levels are highest, and another during the mid-luteal phase, the second half of the cycle, when progesterone is highest.

During the first phase, the participants performed knee extensions with one leg. They did the same exercises using the other leg during the next phase. 

The participants were instructed throughout the study to ingest deuterium oxide, which helped the researchers track muscle protein synthesis (MPS). MPS shows how the body utilizes amino acids to build muscle.

The researchers also collected saliva, urine, blood samples, and muscle biopsies from the participants’ legs to measure myofibrillar protein breakdown (MPB), which shows whether muscles are gaining or losing protein. 

While exercise boosted MPS, the timing didn’t appear to affect MPS or MPB.

The finding suggests that female hormones probably don’t influence how muscle responds to exercise. As such, “women can reap the benefits of lifting weights at any point during the cycle,” Colenso-Semple told Health.

That said, it’s worth noting that the study included only 12 people, so it’s difficult to know if the results would apply to the general population.

Furthermore, the researchers only investigated one aspect of cycle syncing’s effects on exercise: building muscle. “There are many other aspects of exercise that may vary across the menstrual cycle,” Taylor told Health.

Banulis would like to see future studies investigate the long-term impact of female hormones on muscle growth, endurance, and recovery. “It’s also important to study how factors like birth control and perimenopause impact exercise outcomes,” she said.

Although “there’s no evidence to support the message that certain types of exercise are better suited for specific points during the cycle,” Colenso-Semple said, there may be other reasons you’d rather work out at certain times of the month. 

The menstrual cycle—and the hormone fluctuations it triggers—can absolutely affect how you feel. Banulis explained that increasing estrogen levels during the follicular phase may leave you feeling more energized. During the second half of the cycle, i.e., the luteal phase, progesterone levels pick up, potentially making you feel stronger, she added. 

These hormonal changes may cause some people to feel bloated and crampy, which could affect their ability (and desire) to work out, Taylor said. On the flip side, working out—and the release of endorphins—could alleviate pain and menstrual cramps or help with premenstrual dysphoric disorder, or PMDD.

If you feel worn down, it’s totally OK—and understandable—to tweak your exercise plans or take a rest day. 

Banulis’s advice? Listen to your body. “If you’re feeling tired, adjust your workouts, but you don’t need to follow a strict schedule,” she said. “Instead of focusing on syncing workouts to your cycle, focus on overall fitness, proper recovery, and what feels right for your body.”