What to Know About Running and Birth Control and Whether Oral Contraceptives Affect Performance
With more than 400 million tags on TikTok and nearly 95,000 on Instagram, you’ve probably heard about cycle syncing, which refers to timing workouts to the phases of the menstrual cycle — menstruation, follicular, ovulatory, and luteal.
The reason it’s trending: “Each phase has different hormonal changes and physical symptoms that can influence your body’s needs,” explains Dr Brittany Robles, an ob-gyn, certified trainer and owner of PostpartumTrainer.com. Syncing your period with these phases may help endurance athletes train more strategically and yield better performance.
But what about cycle syncing your running when you’re on birth control? While there is research on this, “the very few conclusions we have about effects of the menstrual cycle on athletic performance in normally menstruating women cannot be applied to women on hormonal contraception who do not have the same cycling pattern due to their exogenous hormones,” explains sports medicine physician and endocrinologist Dr Kathryn E. Ackerman medical director of the Female Athlete Program in the Division Sports Medicine at Boston Children’s Hospital.
Plus, different hormonal contraception can have different effects.
That said, here’s what we know, so far, based on scientific research and experts in the space.
Do you need to sync your running to your cycle if you’re on birth control?
For starters, women taking hormonal contraceptives do not experience the same cyclic fluctuations of sex hormones (a.k.a. a menstrual cycle), explains Dr Ellen Casey, a physiatrist at New York City’s Hospital for Special Surgery, “so there is no clear scientific evidence that supports training syncing with birth control.”
“The concept of syncing training across the menstrual cycle is to modify training to fit with the hormonal shifts across the menstrual cycle,” adds Casey. “However, compared to women who have regular menstrual periods, women taking oral contraceptives should have more consistent levels of hormones — both the type our body’s make and the ones in the pill,” which means there may be little to no need to tailor training to those fluctuating hormones.
Robles agrees, though recommends lowering intensity during menstruation, if you’re using a form of birth control that allows you to bleed, or you experience problematic symptoms (think cramping, bloating, headaches) and feel uncomfortable training hard during this time.
Ackerman says there may be a slightly better performance in some naturally menstruating women compared to those on oral contraceptive pills because of the anabolic effects of estrogen and testosterone — both of which will be higher at times in the naturally cycling women than those on oral contraceptive pills. “Estrogen and testosterone have anabolic (muscle-building) effects, so [they] could be beneficial for training and performance,” says Ackerman,
A feel-good hormone, estrogen can also improve mood, make you feel strong, and affects multiple tissues and body processes involved in training (think aerobic capacity, stiffness of soft tissues — ligaments and tendons — bone density, and reaction time), adds Casey.
Meanwhile, testosterone is crucial for bone density, muscle mass, and energy. Though, Ackerman admits, more well-controlled studies are needed to really understand the interplay of various hormones.
How might birth control affect running performance?
While birth control syncing may not be a thing just yet that doesn’t mean that taking it can’t affect you or your training — we just don’t know exactly how yet.
For example, a 2020 systematic review of 42 studies revealed that those using oral contraceptives may experience an inferior exercise performance when compared to naturally menstruating women. To find this, researchers compared the time when you don’t take the oral contraceptive pill to the early follicular phase, which occurs between menstruation and ovulation. They also compared oral contraceptive pill consumption versus all phases of the menstrual cycle except for the early follicular phase. In each case, even if they did see an effect, the “effects tended to be trivial and variable across studies.”
The researchers pointed out that the if performance is a priority, it’s best to adjust your schedule according to your individual needs.
Other research suggests that hormonal birth control can decrease our ability to put on muscle mass. For example, Dr Sarah E. Hill, author of This Is Your Brain On Birth Control, points to one study in which researchers had two groups of women — one on hormonal birth control and one not — do identical strength-training workouts to build muscle mass over 10 weeks.
Despite doing the same routine, women who were on hormonal birth control put on 40 percent less muscle mass. “These patterns are likely driven by the differences in testosterone between hormonal contraceptive users and natural cyclers,” says Hall.
That said, research published in October 2022, revealed that changes in performance across the menstrual cycle might be related to self-reported psychological well-being rather than shifting hormonal concentrations.
In this study, women taking oral contraceptives had more stable performance and psychological well-being over the course of the study. However, it didn’t directly compare performance in users and non-users of oral contraceptives, Casey notes. Those findings may basically come down to the fact that those on oral contraceptives might not experience the variation in performance that those with a regular period might.
What else should runners know about hormonal birth control?
Performance aside, Casey says hormonal birth control can mask menstrual dysfunction that occurs as a result of low energy availability (not eating enough calories to support the demands of daily bodily functions and sports training), which can lead to the Female Athlete Triad — a combo of menstrual dysfunction, low energy availability, and decreased bone mineral density.
This might also hide the symptoms of Relative Energy Deficiency in Sport (RED-S), which refers to poor health and declining athletic performance occurring when athletes don’t get enough fuel through food to support energy demands.
Other menstrual dysfunction that might get masked by hormonal birth control, according to Ackerman, includes polycystic ovary syndrome, thyroid dysfunction, and prolactinoma, which is a noncancerous tumor of the pituitary gland, which can change levels of sex hormones.
An ever bigger issue: “to determine if someone has menstrual dysfunction, they need to be off of exogenous hormones for at least six weeks before doing reproductive hormonal testing,” Ackerman says.
On the other hand, some women need to go on birth control not just for family planning purposes, but other health concerns. For example, hormonal birth control may help an athlete with reduction in menstrual pain, cessation of menstruation all together, and improvement in anemia, explains Dr Erin Fleurant, an ob-gyn at Northwestern Medicine.
For example, if an athlete has such irregular cycles they can’t predict when they will be menstruating and that’s causing stress when selecting competition dates, the addition of a combined hormonal birth control can help give them a predictable, monthly cycle. Or, if an athlete has such heavy bleeding that they are becoming anemic, and therefore compromising their training, birth control could help lessen menstrual bleeding. Regular, but painful periods? Combined hormonal birth control could also minimise these symptoms to improve athletic performance.
The Bottom Line on Birth Control and Running
With so little quality research available on cycle syncing with birth control, it’s hard to know where to land on this issue. For now “all we can say is that exercise performance is pretty consistent throughout the oral contraceptive pill cycle with little need to adjust training on active pill versus placebo pill days,” Ackerman says. That’s why “people should just adjust training based on their own personal trends,” she adds.
Unfortunately it’s a little more complicated than turning down the intensity of your training when you’re feeling tired or dialing it up when you’re feeling energised, especially considering estrogen and progesterone can have various effects on how you feel, albeit the degree may differ from person to person.
To best understand training and your cycle, “women should track their cycle and see how they feel, how they respond, and adjust accordingly,” advises Ackerman. “Some have menstrual cramping. Some get a burst of energy. Others feel groggy at specific times. There are ways to mitigate symptoms, so don’t overthink the cycle for now and do what works best for you.”