For access to all of our training, gear, and race coverage, plus exclusive training plans, FinisherPix photos, event discounts, and GPS apps, sign up for Outside+.
Written by: Lewis G. Maharam, MD
The menstrual irregularities associated with running have long been recognized by doctors treating runners. Amenorrhea (absence of 3 to 12 consecutive menstrual periods) and oligomenorrhea (irregular, infrequent menstruation: 6 to 9 menstrual periods per year, or cycle length less than 90 days but greater than 35 days) have both been seen in exercising women in all sports. In fact, up to 50 percent of all women runners may see this happen to their periods.
Increased exercise causes a decrease in the hormones that control menstruation (for the technically minded, the hormones involved include gonadotropin-releasing hormone, or GnRH, from the hypothalamus; luteinizing hormone [LH] from the pituitary gland; and follicular stimulating hormone [FSH], also from the pituitary gland). Those hormones control your menstrual cycle, so a decrease in their levels or a change in their ratio means that your cycle goes out of whack.
The risk factors associated with these menstrual irregularities include the following:
- Increased mileage and intensity (different for everyone)
- Prepubertal training (regular training before puberty is reached)
- Delayed onset of initial period
- Low body weight/weight loss
- Low body fat/fat loss
- Nulliparity (never having carried a pregnancy)
- Never used oral contraceptive pills
- Diet deficient in protein and total calories
- History of a disordered eating pattern: bulimia or anorexia
- Family history of amenorrhea and/or oligomenorrhea
- Psychological stress
The more risk factors you have, the more likely you are to have irregular or absent periods.
The exact cause of the decreased GnRH, which in turn triggers the decrease of the other hormones, is still under discussion among physicians. Causes thought to be involved include b-endorphins and other hormones in the body whose levels are increased with exercise.
Evaluation and treatment of menstrual dysfunction are important because if left unchecked and brushed off as a normal consequence of running, this condition can lead to osteoporosis; stress fractures; increased growth of the endometrium (the mucous membrane lining the uterus), resulting in heavier, more painful periods later; and other soft tissue injuries.
A physician should take a thorough history and do a complete physical examination when you present with this problem. It is always necessary to check for pregnancy first even if you are using birth control; no system other than abstinence is foolproof. Your physician should evaluate your training schedule and any changes in it over the previous six months or the time you were having menstrual irregularity. A full diet evaluation should be done, too, as well as a review of what drugs you are taking and whether you have had recent stress fractures or psychological stress.
Next up is the laboratory evaluation. Your doctor will probably order these tests:
- Urine pregnancy test (if indicated).
- Thyroid stimulating hormone (TSH) and prolactin (luteotropic hormone, or LTH) levels (TSH is a hormone that helps regulate the thyroid gland; LTH is a hormone associated with lactation).
- A progestin challenge test (10 mg of Provera given for five days should bring on a period within two to five days, indicating adequate amounts of circulating estrogen in your body; this is considered a “positive test”).
- FSH/LH levels if the progestin challenge test is negative. If the FSH/LH is high, ovarian failure, not a hormone problem, is the issue. If low, it is athletic amenorrhea.
Treatment is simple. Although decreasing training and increasing weight usually solves the problem, I know few runners who go for this plan. Instead, hormonal treatment to bring on periods every three months or use of oral contraceptives is an alternative that some obgyns feel comfortable prescribing. I have found that referral to a good sports nutritionist to be sure the protein intake is at 1–2 g/kg/day along with adequate calcium (1,500 mg/d) is a good first step. If stress is deemed the cause and running alone doesn’t destress (or is causing the stress), a referral to a good psychologist sometimes does the trick.
This article was adapted from the new book Running Doc’s Guide to Healthy Running with permission of VeloPress. From head to toenails, Running Doc’s book explains healthy running practices and guides runners to the right diagnosis and treatment for over 100 running injuries and related health problems. Running Doc’s Guide to Healthy Running is now available in bookstores, running shops, and online. Download a free sample and preview the contents at velopress.com/runningdoc.