Period Tracking for Female Athletes – RUN

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Should runners with a period track their menstrual cycles with the same attention to detail as HRV, nutritional intake, and sleep? Could period tracking really help athletes crack the code for a PR?

If you spend any time on social media, you probably assume the answer is “yes.” Women’s health and performance – specifically, as it pertains to hormones, is a hot topic right now. There’s no shortage of influencers and self-proclaimed experts offering advice on how to use period tracking to optimize athletic performance, but actual credentialed experts proffering detailed advice and protocols? Those are harder to come by. That’s because the science of period tracking for athletic performance is in its infancy, says Dr. Kelly McNulty, sports physiology researcher at Northumbria University and founder of Period of the Period.

It’s great that we’ve had this boom in menstrual cycle tracking,” says McNulty. “Menstrual cycle tracking is more common now, and it’s advocated for, especially within elite environments, as something athletes should be doing. There’s a tendency that everyone’s a female health expert now, but on the flip side of that, the science isn’t quite there yet. We don’t want to be giving bad advice off low-quality research.”

That’s not to say period tracking is a bad idea – only that athletes should beware of one-size-fits-all advice on how women perform during certain phases of the cycle. Let’s take a deeper look at how to make period tracking work for you, whether you’re just starting out as a runner or looking for a PR.

What the science says about period tracking for runners

Historically, physiological research on female endurance athletes has been limited in comparison to male athletes. The major contributing factor to this dearth of information is a belief that it’s simply “too complicated” to study women – their monthly menstrual cycle and resulting hormonal fluctuations skew otherwise straightforward results. The lack of research on this topic means data collected on males is extrapolated to females, and female athletes usually train based on recommendations made for male athletes.

McNulty was part of a 2021 research team that reviewed more than 5,000 studies across six popular sport and exercise journals, finding that women accounted for only 34% of total participants, with as few as 6% of studies focusing exclusively on females. McNulty later found that even fewer studies looked at women by life stage – a particularly “invisible” cohort is women going through midlife, perimenopause, and menopause. Simply put, the science on women isn’t that great, and though it is an area of increasing interest for researchers, McNulty says it will still be five to 10 years before there’s a robust body of high-quality research.

Still, McNulty warns, “Everybody’s an expert now. And so everyone’s coming out saying that they will tailor your training plan to your menstrual cycle, and it sounds too good to be true in a lot of ways. We don’t want to come in and tell people, ‘No, this is a bad idea,’ but we do feel really strongly about making sure that people know that if you’re paying for someone to do that, and they’re claiming they’re an expert, that nobody’s really fully an expert on that, except for the people who are currently doing the research – and even they don’t have all the answers.”

There are, of course, some already-published studies that indicate hormone fluctuations aren’t a complication; they’re actually key to understanding and optimizing athletic performance in women. Hormones like estrogen and progesterone rise and fall throughout a woman’s month-long menstrual cycle, influencing everything from how she performs in training or racing to how she recovers. Some studies have found hormones may affect ligament laxity, suggesting injury risk may increase at various stages of the cycle. There is also evidence that when hormones fluctuate, so too does a woman’s body’s ability to maintain proper hydration levels, metabolize nutrients, and regulate body temperature – unique factors critical to female athletic performance.

Should you avoid “runner period-tracking apps?”

These studies, plus a growing demand for women-specific health advice, have led to an influx of period-tracking apps for athletes, which help women monitor where they are in their monthly cycles. Some apps even recommend what kind of training to do (or avoid) and when.

Though such apps can be enlightening for female athletes looking for insights on their individual physiology, McNulty and her colleagues warn that there currently isn’t enough research to make standard recommendations related to period tracking and sport performance.

That doesn’t mean that period tracking is a waste of time; only that experts aren’t at the point to confidently say “on X day of the cycle, women are best off doing Y workout and recovering with Z food.” McNulty says the information period-tracking apps give is often generic, and given the variety in menstrual cycle experiences among women, the information presented might not always be suited to the specific athlete. Some may also have privacy concerns with putting highly-sensitive health information into such apps.

While women wait for the scientific community to endorse a substantial body of evidence, there are still things athletes can do, McNulty says: ”If you are a female athlete or a coach/practitioner supporting a female athlete, then I recommend that you dive into the research and learn all you can about the potential effects hormones can have on women’s physiology. But do this with a critical eye.”

McNulty also says women can develop their own “bespoke athlete guidelines,” where each athlete uses her own expertise of her own body to identify patterns in performance. “When you learn more about your own menstrual cycle – what symptoms you experience and how you perform, train, and recover on certain days – you can use your knowledge and understanding to determine what bits of the research might apply to you and which don’t. From there you can begin to tweak and adjust things to maximize or manage performance/training depending where you are in your cycle,” she says.

It’s in these individual experiences of the menstrual cycle – not the advice of an app – where the biggest insights lie. “Every woman is different, and the research is only the beginning from which we can build our individualized content from,” McNulty says. “But this only happens if we understand our bodies first.”

How runners should track their periods for performance

Tracking the menstrual cycle can be as simple as circling a day on a paper calendar or marking an X in your smartphone on the first day of your menstrual flow, or period. The menstrual cycle is counted from the first day of one period up to the first day of your next period.

The average menstrual cycle is 28 days long, but each woman is different. Some women’s periods are so regular that they can predict the day and time that the next one will start. Other women experience menstrual cycles that vary in length. Medically, periods are considered “regular” if they usually come every 24 to 38 days.

That menstrual cycle is further divided into four phases:

Menstrual:
Period “bleeding” begins when levels of the hormones estrogen and progesterone drop. Duration: 1-7 days.

Follicular phase:

The time between the first day of the period and ovulation. Estrogen rises as an egg prepares to be released. Duration: 10-22 days.

Ovulation phase:
The release of the egg from the ovary, mid-cycle. Estrogen peaks just beforehand, and then drops shortly afterward. Duration: 12-24 hours.

Luteal phase:
The time between ovulation and before the start of menstruation. Progesterone is produced, peaks, and then drops. Duration: 9-16 days.

The length of each phase can differ from woman to woman, and it can change over time. The way each woman responds to these hormone fluctuations in each cycle can vary as well; some feel a pronounced effect on their endurance or energy levels, while others notice very little.

If you want to track your period and performance, then, in addition to recording the start dates of each menstrual cycle, you may want to track additional data that will help you identify patterns. In an athletic context, a training log may be the best place for this information, as it will allow the user to more clearly see parallels between where she is in her cycle and how she performed:

How many days your period lasted: Was your period shorter or longer than the month before?
Daily changes in vaginal discharge: clear/white, thick/thin, sticky/slippery
Workout performance: What did you do? Did you hit your goals for the workout? Did it feel harder or easier than when you have done this workout before?
Recovery: Soreness, new injuries, or flare-ups of pre-existing injuries
Hunger and thirst: What did you eat after your workout? Was this satisfying? Were you more thirsty than usual?
Premenstrual syndrome (PMS) symptoms: Cramping, headaches, moodiness, forgetfulness, bloating, breast tenderness

You can also download apps (sometimes for free) to track periods. While many period-tracking apps are focused on ovulation and fertility, a growing number (like Clue and Flo) allow women to log exercise and energy levels. Several activity trackers (including Garmin and Fitbit) have also added period-tracking functions to their logs.

There are also specialized fitness apps targeted specifically to active women popping up more recently. Wild AI and FitrWoman sync with common training platforms like Strava, allowing the user to see daily activities alongside menstrual cycle data. Coach management software AthleteMonitoring is designed to help coaches plan light or heavy workloads according to each athlete’s individual cycle in order to maximize performance while minimizing the risk of injury. It also detects and flags irregular cycles and potential medical issues, offering proactive recommendations for users and coaches.

Whether you go the pencil-and-paper route or download a tracking app, the premise is the same: record the same information every day, and patterns will begin to emerge with time.

“No matter your method of tracking, I would encourage athletes to track for at least three months to allow meaningful conclusions about their cycle patterns to be made,” McNulty says. “Collect your own data, look for patterns, and make reasonable adjustments, using the evidence base to inform your decisions.

A note on birth control and period tracking

There is very little research on various oral contraceptives (i.e., the pill) and its effects on performance, training, and recovery. There’s even less on other contraception methods, such as IUDs. Still, it’s worth using period tracking in your experiment of one.

“I think it’s just as important, if not more important, for female athletes on hormonal contraception to take control and track,” McNulty says. “My advice is to track what symptoms you experience and how you perform, train, and recover at different points during your pill cycle or whichever hormonal contraceptive ‘cycle’ you are on.”

This is especially true when switching from one hormonal contraceptive to another, or transitioning on or off hormonal contraceptives. “This will give you the best personalized information,” McNulty said. “This will enable you to make a plan and advocate for yourself when talking to your doctor or support team about your choice of hormonal contraception to make sure you are taking the one that suits you best.”

Perimenopause, menopause, and period tracking

Is period tracking a useful tool for athletes who in perimenopause and menopause? McNulty says it could be:

“In that stage of life, there’s a lot of things that are changing. It’s a bit of a hormonal rollercoaster that’s going on, and a gradual decline in that hormonal rollercoaster over time. But we’ve got to think beyond that reduction in sex hormones – things like osteoporosis, increased risk of heart disease. Cycle tracking, particularly around that point in life, could be beneficial in terms of helping you notice symptoms and cycle changes. It can help you inform conversations that you might have with a doctor. It could be a piece of the puzzle with symptoms like joint pain or muscle pain during menopause.

Red flags in period tracking

Talk to your doctor or nurse if you have menstrual cycles that are longer than 38 days or shorter than 24 days. In addition, consult your health care provider if:

Your periods suddenly stop for more than 90 days (and you’re not pregnant)
Your periods become erratic after having been regular
You bleed for more than seven days
You bleed between periods (also known as “spotting”)
You develop severe pain during your period
You experience extreme mood changes during your cycle