Athletes who get a period have likely experienced times when period symptoms have gotten in the way of their running. Karen Duncan, MD, associate professor in the Department of Obstetrics and Gynecology at NYU Langone Health, speaks to Runner’s World about topics ranging from how to manage a heavy flow during a run to whether it’s safe to use birth control to skip a period for a race.

As with things like fuel and clothing, Dr. Duncan recommends you not try any new methods to manage your flow on race day. “Try a few options out first when you’re home, then out on long runs, so there are no surprises,” she adds.

If you experience changes or skips in cycle, Dr. Duncan advises speaking to your doctor. “Amenorrhea, or missed periods, can happen due to heavy exercise and training, but it can also be due to caloric restriction, unhealthy weight loss, or even an undiagnosed thyroid condition,” she says.

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