Should You Alter Your Period to Perform Better?

Updated February 26, 2024 12:14PM

Vomit-inducing cramps leave her bed-ridden for two to three days at a time. If she pushes her body too hard in training during that time, she tends to get injured. At the 2019 Prague marathon, she recalls retaining so much water weight (due to fluctuations in hormones), she couldn’t fit into her uniform. Advice she has been given from friends varies from nutritional shakes to, “It might go away if you have a baby.”

The professional marathoner has worked hard to figure out how to train and race around her period, but even the best-laid plans backfire. In 2017, Nukuri was looking to run a fast marathon course like London, but ultimately chose to run Boston (a hillier course) based on her cycle. She calculated her period would start a week after Boston, but it came the day before the race. Her plan was foiled again at the New York City Marathon that same year when, she says, she was at peak fitness. Her period came a week earlier than expected.

“If I didn’t have these kinds of issues, I feel like my running career would have been much better,” says the three-time Burundian-American Olympic runner.

Nukuri isn’t the only elite female runner who has spoke publicly about how menstruation impacting her running. Olympians Eilish McColgan and Dina Asher-Smith have made public announcements calling for more open-dialogue and sports science research on how the menstrual cycle impacts performance. Athletes are finding they have to advocate for themselves in the doctor’s office. There isn’t a one-size-fits all band-aid a doctor can prescribe women to address period concerns.

The Period as a Vital Sign

In the summer of 2019, Nukuri got an MRI for a hamstring tear. The images revealed she had something in her lower abdomen. An ultrasound showed uterine fibroids. Surgically removing them eased some of her usual discomfort around her period, and, she says, it gave her peace of mind that she wasn’t “crazy.” Statistics show that almost 25 percent of Black women ages 18-30 have uterine fibroids compared to 6 percent of white women.

So, why doesn’t she just cut out the period all together? Many women now eliminate them temporarily through hormonal contraception by skipping the placebo pill. In her TEDx talk “Making Periods Optional,” OB-GYN and cofounder of Pandia Health, Sophia Yen says it’s unnatural for women to have as many periods in their lifetime as they do. She promotes #periodsoptional to decrease ovarian, endometrial, and colorectal cancer.

“In every sport you want to have as much blood on board so you can get oxygen to yourself and maximize your performance. The number one cause of anemia in a menstruating woman is menstruation. We are being blood let one week out of a four,” she says.

But Trent Stellingwerff, Senior Advisor for Research and Development at the Canadian Sport Institute Pacific, disagrees, “For women running five to six hours a week—no matter the pace—the best canary in the coal mine we have is your menstrual cycle status. I would not cut out the period because [then] we don’t have the ability, without extensive bloodwork and ovulation tests, to know their energy availability status,” says Stellingwerff whose wife, a 1500-meter Olympic runner, has participated in some of his studies.

Everyone’s Period is Different

Nukuri was 23 and coming off a stellar college running career when she first saw a doctor for her heavy bleeding and cramps that began soon after she started her period at 18 years old. She was offered the pill (hormonal birth control), but not an ultrasound (which she thinks might have discovered the fibroids). “It made me feel really bad. I never felt like I was getting in shape,” she says. Three years later, she decided to go off the birth control and she started performing better.

Nukuri says she’s tried everything to ease her negative period symptoms, but she’s found what might work for one woman doesn’t necessarily work for everyone. “Sometimes it depends on how much stress you’re under with work or your personal life,” she says.

Stellingwerff concurs. “The female menstrual cycle is incredibly complex,” he says. A normal cycle is 28 days, plus or minus seven days. When a woman performs best during her cycle is very individualistic.

“I’ve seen women on birth control give unbelievable performances. I’ve seen women off birth control give unbelievable performances. I’ve seen women on every day and every stage of the menstrual cycle give unbelievable performances,” says Stellingwerff.

Case in point: Sara Vaughn, miler turned marathoner and mother of four, who has peaked at all points in her cycle, even during her period. “I’ve had some of my best races mid-week one of my cycle.” She cites making her first Team USA as an example. “I’d started my period the day in between the prelim and the final.”

Vaughn has noticed that after every one of her pregnancies, her period symptoms have changed, sometimes for the better, sometimes worse. “I’ve always just reminded myself to give your body a chance to do what you’ve been training for, regardless of how you feel. You can still get the job done.”

Let’s Talk About Periods

While competing at the University of Colorado in Boulder, the NCAA All-American in cross-country says she never spoke to any of her coaches about her period. But the women on the team shared with each other. “There was a belief among my female teammates that losing your period was a badge of honor. Implying that if you were getting it, you weren’t training hard enough,” Vaughn recalls.

Vaughn has never lost her period (which she started at 15) unless she’s been pregnant or nursing. Her sophomore year in college she remembers a trip to see a team doctor because she wasn’t feeling well. She hadn’t had her period for a couple months, and she was on birth control. “Instead of saying, ‘This is a health issue. Or maybe you’re pregnant,’ they were like, ‘You’re training really hard. This makes sense.’ Almost like a pat on the back,” says Vaughn who was pregnant with her first child, Kiki.

“I will encourage my children not to go on hormonal birth control,” says Vaughn who didn’t like how it made her feel. “You have no monthly check on the status of your health.”

Internationally renowned exercise physiologist and nutritionist Stacy Sims also discourages manipulating the menstrual cycle. “I try to get people not to use oral contraceptive pills or hormonal contraceptives to manipulate their cycle,” she says. “Then they are downregulating their own natural endocrine cycle which we want because it will tell us if we are overtraining, overreaching, or overstressed.” She warns this can then lead to RED-S (Relative Energy Deficiency in Sport), formerly referred to as the female athlete triad.

Sims argues that we can train according to our menstrual cycle, that there are hormonal patterns in the cycle consistent in most women.

Get To Know Your Menstrual Cycle

From day one (first day of bleeding) through day 13, estrogen and progesterone are at their lowest. The body is most resilient to stress and the immune system is strong. The body is most receptive to training for power and speed. During days 15-21, she recommends more steady state work, for example hills. The five days before the period starts progesterone and estrogen levels are high. The body is least resilient to stress and the immune system is more prone to inflammation. Sims suggests females focus on recovery and exercises that develop balance and technique. If cramps are bad, consider doing 5 x 20-30 second surges with lots of recovery. Sims says it produces an anti-inflammatory and growth hormone response which tells the body to dial down the cramping.

“It’s not about talking about the negative points in the menstrual cycle, because there shouldn’t be a negative point,” says Sims whose TED talk Women are Not Small Men points to nutrition as the tool to level the playing field. She encourages women to learn how to leverage how they respond to training at different points in their cycle to lead to better performance.

However, Stellingwerff argues that it’s too early to propose female runners follow a menstrual cycle formula. The current data, he says, is based on studies that were “moderately to poorly done” over the past ten years. “The ability to do gold standard methodology in female subjects in exercise physiology is pretty challenging,” he says due to the many variables. Is a woman on birth control or not? Is the birth control hormone-based or copper-based? “It’s a real challenge to make confident conclusions from data when the methods have been poorly conducted.”

Stellingwerff and Sims agree on one thing: Female runners should track their own individual data for several months. If you consistently nail workouts on day five of your cycle, take note. If you consistently feel lousy the last week of your cycle, don’t plan a key race for that week.

When the science is still so lacking, personal data is all you can really rely on.