Menstrual issues in young female athletes

Regularly missing periods can often be a sign that young female athletes aren't getting adequate nutrition — which could have potentially serious consequences.

For many girls and young women who compete at the top levels of their sports, not having a regular menstrual period is often seen as a normal part of being an athlete — or even a badge of honor signifying hard work and intense physical training. But the reality is, regularly missing periods can often be a sign that a girl isn't getting adequate nutrition. Her hormone production is likely off balance — which is a problem that could have potentially serious consequences in the near term and throughout life.

Normal reproductive function

A healthy female reproductive system depends on a finely tuned feedback system between three vital organs: the hypothalamus and the pituitary gland — both located in the brain — and the ovaries. These three together are called the hypothalamic-pituitary-gonadal axis.

The hypothalamus kicks off the reproductive cycle by sending out gonadotropin-releasing hormone (Gn-RH), which prompts the pituitary to release follicle-stimulating hormone (FSH). FSH signals a few select immature eggs (follicles) in the ovaries to begin the maturation process. As these follicles mature, they release estrogen. The increased levels of estrogen then signal back to the hypothalamus and the pituitary gland that ovulation — the release of an egg for potential fertilization — is near.

Meanwhile, the pituitary gland is producing another hormone called luteinizing hormone (LH). Shortly before ovulation, a surge of LH prompts the release of the egg. In addition to estrogen, the now-empty follicle begins to produce the hormone progesterone, which helps prepare the uterus for a possible pregnancy.

If the released egg isn't fertilized within 12 to 24 hours, the egg will dissolve and the lining of the uterus will be shed during the menstrual period. Following menstruation, estrogen and progesterone levels are low again, which triggers the hypothalamus to once again release FSH, beginning a fresh cycle.

Missing menstrual periods

A critical component of the ovulatory cycle is an adequate supply of energy. When a girl or young woman doesn't eat enough calories to balance her energy account, her body tries to conserve energy. One way it does this is by suppressing production of the Gn-RH, with the subsequent ripple effects on the pituitary gland and ovaries. The midcycle LH surge may not occur, the follicles will fail to develop normally, and estrogen production falls. As a result, ovulation can occur infrequently — or not at all. The period is usually light or absent. The technical term for this is functional hypothalamic amenorrhea. Amenorrhea means the absence of periods.

For some girls who begin sports training at an early age, intense exercise combined with inadequate nutrition can result in delayed puberty. Girls who haven't had their first menstrual cycle by age 15 are said to have primary amenorrhea. Missing more than three periods in a row after starting regular menstrual cycles is referred to as secondary amenorrhea. Going more than 35 days between periods is called oligomenorrhea.

The physical stress of intense exercise, as well as emotional and psychological stress, can contribute to hormonal abnormalities. Competition can generate stress and anxiety, as can peer pressure, family dynamics and just the challenges of growing up. In response to these and other physical and emotional stressors, the body can release higher levels of hormones such as cortisol and catecholamines (chemicals that affect the nervous system). In addition, the production of growth hormone can decrease. All of these changes can have a negative effect on menstrual function.

Leptin, a hormone produced in fat tissue, is lower in athletes and in women with low body fat. Since leptin stimulates the Gn-RH secretion that initiates menstrual cycles, a leptin deficiency can contribute to not having a normal period.

Genetics can play a role, too. Some girls mature later than other girls do; other girls are more vulnerable to hormonal fluctuations. And it's likely that each girl has a different internal balance point that determines when, or if, hormonal abnormalities occur.

Nov. 04, 2016