Why runners who menstruate should track their cycles

Runners who menstruate find it useful to track their periods, since fluctuations in the menstrual cycle can affect many aspects of training, such as recovery, training readiness, fuelling needs and mood. Apple recently published a study of more than 50,000 female subjects that emphasize the importance of the menstrual cycle’s overall health effects. 

Tracking your cycle

So you know what to look for when you’re tracking your cycle, but how are you supposed to do it? Apple has cycle tracking on iPhones and Apple Watches, but there are many other apps available, both on phones and online. You can also track it on paper, noting when you start your period and how long it lasts, plus how heavy it was. Mark these notes down on a calendar, then do the same for each period after that. With this, you’ll be able to see if you’re experiencing any irregularities, and if so, you’ll know that it may be worth chatting with a physician about whether these deviations pose any health risks.

The findings

The Apple Women’s Health Study was designed with the goal of helping women understand their cycles and what period regularities (or irregularities) can mean for them. It found, for example, that of the more than 50,000 participants, 12 per cent reported a PCOS (polycystic ovary syndrome) diagnosis. That group of 12 per cent had more than four times the risk of developing endometrial hyperplasia, which the team calls “pre-cancer of the uterus,” than women without a PCOS diagnosis. These women are also two and a half times more at risk of developing uterine cancer.

The team also found that close to six per cent of study participants said their menstrual cycles took five or more years to reach “cycle regularity” after they had their first period. Despite the fact that their cycles started years ago, this delayed regularity is another sign of an increased risk of endometrial hyperplasia and uterine cancer. Those who reported that they fell into a regular cycle within a year of their first period are much less likely to face these risks.

It was noted that “cycle deviations, like irregular or prolonged periods” can be “a sign of underlying conditions including PCOS, fibroids, malignancies or infections.” This is why it’s important for women to track their cycles, as a first step toward identifying any health risks arising from menstrual abnormalities.