While it is not entirely uncommon to have female runners miss menstrual cycles with running and/or general cardiovascular exercise, it is NOT NORMAL for a female runner to miss menstrual cycles. Runners with decreased periods have a higher risk of injuries, especially stress fractures. The research has found runners without a menstrual cycle are 2-4 times more likely to develop a stress fracture.

The reason for the loss of the menstrual cycle may be eating inadequate calories needed to support regular menstruation, health and performance. The other reason can be due to excessive exercise, leading to the runner burning more calories than she is eating, which is a calorie deficit. Often, it is due to a combination of both of these factors.

Runners who have disordered eating and decreased bone density in addition to menstrual dysfunction are even more at risk, as this makes them have what is called the female athlete triad (Triad). While any one of these alone increases a female’s risk of injury, having a combination or all of them puts the female runner at a very elevated risk for injury compared to females demonstrating none of these. These signs of the Triad are more common than most people anticipate. For instance, a recent article by Thein-Nissenbaum, et al, in 2011, found that disordered eating was found in 35% of high school female athletes, while menstrual dysfunction was found in 19% of high school female athletes. Unfortunately, these characteristics are often underreported and many female athletes do not realize the risks involved, sometimes even viewing missing menstrual cycles as a convenience. Menstrual dysfunction is defined in this study as the following, “9 or fewer menstrual cycles in the past 12 months, or the lack of menstruation in athletes over the age of 15.”

If you are a female runner or parent of a female runner with an abnormal or missing menstrual cycle related to exercise, we recommend you discuss this with your doctor, particularly one that is well versed in sports medicine.

The author of this article is Ryan Perry, PT, DPT, OCS, CSCS, MTC, FAAOMPT from NovaCare at Fitness Formula Club- North Ave.