Missed Periods and Marathon Training

Some runners with very low body fat or those who are training very intensely (for an endurance race such as a marathon) do occasionally miss their period. Irregularities in the menstrual cycle happen more frequently with running than with any other sport.

The amount of running is definitely a factor. Some people assigned female at birth who run longer distances (>30 miles per week) report increased stress associated with running, as compared to those who run middle distances (15 to 30 miles per week), suggesting there may be a correlation between the stress response and a missed period.

Missing one period is usually not cause for concern, but it most likely means you didn't ovulate that month. So if you're trying to get pregnant, training for a marathon or other endurance event may not be compatible with your goals to conceive.

Asian woman running
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Exercise Amenorrhea Is a Serious Concern

If you've missed more than three periods in a row, you're dealing with a more serious issue. The technical term for this loss of menstruation is amenorrhea.

Experts suggest that exercise-associated amenorrhea develops when caloric intake is less than what burns with exercise and other daily activities. Some women who develop amenorrhea as a result of strenuous exercise also have low body weight, defined as a weight of less than 10% of the ideal body weight.

Missed periods may also be a sign of a poor diet, so you should talk to a healthcare provider to make sure you're eating a healthy, balanced diet and don't have any nutritional deficiencies. Try to determine how many calories you need to make sure you're consuming enough to make up for all the calories you're burning through exercise.

You especially need to make sure you're getting enough protein and iron in your diet. If you're a vegetarian, you may be even more susceptible to amenorrhea, as there may not be enough protein, iron, and calories in your diet.

Low estrogen levels could also be to blame, because your body needs the right amount of estrogen to ovulate. To boost your estrogen levels, try eating foods rich in zinc, such as nuts, seeds, and fish, vitamin B6, found in peppers, eggs, chicken and brown rice and taking a multivitamin that contains magnesium. Estrogen levels can also be influenced by other factors such as sleep and stress, so make sure that you're giving your body and mind time to recover and relax.

People assigned female at birth who are anorexic are known to experience amenorrhea. Although amenorrhea exists among those no eating disorders, the loss of periods is certainly a red flag that restrictive eating behaviors might be the culprit. If you're a running coach, especially one who works with teenagers, be on the lookout for symptoms such as loss of periods and restrictive eating behaviors.

Talk to a Healthcare Provider If You Experience Amenorrhea

Whatever the cause may be, missing more than one period in a row is a serious concern for pre-menopausal people assigned female at birth because it's associated with infertility, osteoporosis, breast and vaginal atrophy, and potentially an increased risk of heart disease. Hormonal or nutritional deficiency issues may lead to other problems, such as stress fractures. Schedule an appointment with a healthcare provider and/or OB/GYN to determine the cause and get the proper medical treatment.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Rebar R. Evaluation of amenorrhea, anovulation, and abnormal bleeding. In: Feingold KR, Anawalt B, Boyce A, et al., editors. Endotext . South Dartmouth (MA): MDText.com, Inc.

  3. Welt CK. Absent or irregular periods (beyond the basics). UpToDate.

  4. Shufelt CL, Torbati T, Dutra E. Hypothalamic amenorrhea and the long-term health consequencesSemin Reprod Med. 2017;35(3):256-262. doi:10.1055/s-0037-1603581

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By Christine Luff
Christine Many Luff is a personal trainer, fitness nutrition specialist, and Road Runners Club of America Certified Coach.