By Elissa Rosen, MD, CEDS
The following is the first of a four-part series on the Health Myths of the Female Athlete
The number of females participating in sports is on the rise. The 2016 Olympic Games in Rio set the record for female participation at 45.2 percent of total athletes. (1) Since 2015, over half of runners participating in half marathons in the United States are female. (2) With the increased participation of females in sports comes the need for individuals who work with female athletes to have a better understanding of how males and females might differ in their responses to athletic training. In addition, it is important to recognize the ways in which the female body might signal that there is a problem that, if ignored, may ultimately lead to not only decreased performance but also to negative health consequences. You can listen to me address some of these myths on this episode of the PHIT for a Queen podcast. Here are even more scientific details to back up our podcast discussion.
Myth 1: Amenorrhea in a female athlete is an expected consequence of sport participation and is nothing to be concerned about.
Truth: Amenorrhea, or absence of a menstrual cycle for three months or more, is a red flag in an athlete. The most common cause of amenorrhea, excluding pregnancy, in athletes is due to what is called functional hypothalamic amenorrhea. The hypothalamus is the hormone regulatory center located in our brain. In an athlete who is under fueling for their sport, for example, the hypothalamus will respond to the energy deficit by reducing the release of hormones that allow for normal menstruation. Why? Because the brain is smart and wants to conserve the precious energy the body does get for purposes other than reproduction. The brain knows that a pregnancy in someone who is not getting enough nutrition for themselves is not a priority and in fact should be prevented. Exercise itself (especially exercise of higher intensity, longer duration, and greater frequency) as well as stress can also be triggers for hypothalamic amenorrhea. Most of the time hypothalamic amenorrhea in an athlete occurs because of a combination of all three factors.
So, what’s the big deal with amenorrhea? Outside of the fact that athletes with amenorrhea who are actively seeking to become pregnant will likely experience fertility issues until their body is naturally able to menstruate, amenorrhea leads to bone density loss. It turns out that estrogen, one of our reproductive hormones that increases during a normal menstrual cycle, is critical for maintaining a healthy skeleton. In those with hypothalamic amenorrhea, estrogen levels will be low since the hypothalamus has shut down its release of the hormone so much so that reproductive hormones decrease to pre-pubescent levels. Many other hormonal changes will also favor ongoing bone loss in athletes who are under fueling with the net effect being decreased bone density due to a combination of both decreased new bone formation and increased bone breakdown. Bone loss can be severe with more than a 2 percent decrease in bone density for every year with amenorrhea. As 90 percent of our bone density is accrued by our late teens and early twenties, this bone loss can be irreversible especially as we get older and less capable of laying down more bone. On top of all of this, low bone density will increase an athlete’s risk of bone stress injuries including the dreaded stress fracture that usually mandates months away from sport participation.
References:
1. Olympic Site: https://www.olympic.org/women-in-sport/background/statistics
2. Competitor https://running.competitor.com/2017/06/news/new-report-2016-marathon-half-participation_165419