Sync Your Workouts and Menstrual Cycle to Maximize Gains

In 2015, when British tennis player Heather Watson flamed out at the Australian Open in the first round, she blamed her poor performance on her period. "I think it's just one of these things that I have," she said. "Girl things." The following year, Olympics bronze-medal swimmer Fu Yuanhui admitted in a poolside interview that her period left her feeling weak and tired in the run-up to the women's 4x100m medley relay. In 2019, British runner Eilish McColgan told BBC Sport she had to pull out of a race after getting her period because she "felt flat, heavy, tired."

It's only recently that athletes have been more transparent about how the menstrual cycle affects performance. Science may say that the effectiveness of your workouts while you're actually on your period remains the same, according to 2006 research on female athletes in the International Journal of Neuroscience, but any woman who's ever worked out just before or during her period knows that it can absolutely mess with your game.

To get ahead of these dips in production, Dawn Scott, high-performance coach of the U.S. women's national soccer team, said in 2019—after the team's World Cup victory—that the players use the period-tracking app FitrWoman to help mitigate hormone-related performance shifts. Where you are in your cycle matters because hormone fluctuations can affect how hard you go, what gains you can make and even your risk for your injury.

Not sure what's going on during your cycle besides the obvious PMS symptoms and actual period? There are four phases: menstruation, the follicular phase, ovulation and the luteal phase. And the two key hormones involved are estrogen and progesterone.

"The follicular phase, or the time from your period until ovulation, is when estrogen is increasing," said Sharon Kressel, M.D., an OB-GYN with Advantia Health in Washington, D.C. "After about two weeks, progesterone—an estrogen-inhibiting hormone—starts rising. That's the start of the luteal phase, which occurs from ovulation until your period."

'Timing certain activities around your cycle is a great way to maintain a healthy momentum.'

Strength training in the follicular phase led to bigger gains in muscle strength compared to training in the luteal phase, one 2014 study published in the journal SpringerPlus found. Research in 2017 in the Journal of Sports Medicine and Physical Fitness confirmed that resistance training during the first two weeks of the menstrual cycle (which includes your actual period) is more beneficial than in the last two weeks.

While scientists don't know exactly why training during the follicular phase leads to strength increases, estrogen was shown to help in muscle growth in 2019 research published in Frontiers in Psychology. And considering that women approaching menopause are losing both estrogen and muscle mass, there's definitely a link there, Kressel said. Plus, older research shows that estrogen is directly involved with metabolism (for example, in maintaining a healthy weight).

Sure, working out while you're actively bleeding, in a word, sucks. But! "Exercise can help you to boost the feel-good hormones called endorphins in your body," said Lynae Brayboy, M.D., chief medical officer at the reproductive health app and period tracker Clue. And endorphins are a natural painkiller, which may help with cramps and other discomfort.

Meanwhile, endurance can suffer during the luteal phase. Think about a steady-paced treadmill run or bike ride: The longer you go, the hotter you get. During the luteal phase of the cycle, progesterone rises significantly in the body—and that's linked to a higher body temperature, Brayboy said. "It rises by at least 0.4 degrees Celsius after ovulation and stays high until menstruation," she explained. As a result, you might find it harder to hit max lifts or feel worse during longer workouts.

The luteal phase, though, is when you're least at risk for injury. Hormonal changes can impact your muscles and tendons, found a 2021 study published in the journal Frontiers in Physiology on international female soccer players. Injuries occurred almost twice as often in the late follicular phase compared to the early follicular or luteal phase.

"We know that during pregnancy, progesterone can make your joints more relaxed," Kressel said—a factor that would also apply when that hormone is high during the luteal phase. So it's important to make sure you're warming up properly during that first phase of your period, when you're more at risk for injury, so you can avoid any pulled or tweaked muscles.

Of course, your hormone levels aren't surging or dropping by a huge amount, Kressel said (not even close to what occurs during pregnancy), so it's not like you're guaranteed to tear your ACL during a company kickball game if you just finished your period. It's just something to be aware of if you are pushing yourself.

"The best way of understanding your symptoms throughout your cycle is by tracking them," Brayboy said. "This can help you prepare for common symptoms—like fatigue or cramping—which might make it hard for you to exercise. And timing certain activities around your cycle is a great way to maintain a healthy momentum."

The bad news: Your period isn't really an excuse to skip the gym. That said, your health isn't about missing one or two days—it's about looking at the big picture, Kressel explained: "You might find that working out makes you feel better. But if you feel like you need to take a couple of days off because of your period, grant yourself that permission."