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Periods are important. Period.

Updated: Jul 20, 2023



Whether it was a chat with your mom, a google search, or the “Care and Keeping of You” book that taught you about periods, you probably learned that a period is about a week of every month where the uterus sheds blood due to hormone changes in the female body. It’s something that females can expect to experience from puberty through midlife when menopause occurs, except when pregnant. Loss of period for 3 months or periods 45 days apart, with no other anatomical or biological causes such as Polycystic Ovary Syndrome (PCOS), is considered Functional Hypothalamic Ammenorhea (FHA).


When I finally got my period in high school – the last of my friends – it was extremely irregular, if it came at all, which I’ll be honest at the time I thought was great. My pediatrician said that the irregularity was because I was active. I internalized this message as “if I am active and healthy, I don’t get my period, and if I do get my period, I’m not working out enough”. You can probably see how this created a toxic relationship with food, exercise, and my period.


Years later, I finally came to understand how important having a regular period was for a female athlete. The reality is, to be a strong, successful athlete, you need to be having a regular period. A “normal” period occurs every 23-35 days, with 28 days being the average. What’s important to know is your normal. You can use app or a calendar to track how many days your period lasts, and how frequently it comes. Changes in these numbers may signify a change in energy availability, and can be a cue to take a closer look at your fueling and training (after any gynecological, thyroid, or other hormone problems have been ruled out).


Your period is a vital sign, a tangible marker of your body’s health, just like your heart rate. If you are missing your period, or if your cycles are becoming further apart, your body is trying to tell you something: I don’t have enough energy to support the hormones and physiologic functions needed to menstruate! That also means that your body might also not have enough energy to do things like grow hair, build muscle, protect your heart, repair tissues or recover from a hard workout. Not repairing muscle, connective tissue, or bone ultimately leads to injury. This is the basis of what we know as RED-s (check out RED-S: More Than a Triad and RED-S for more information).


The primary female hormone is estrogen, and having adequate levels of estrogen is key to having a regular menstrual cycle. Outside of the reproductive system, estrogen increases osteoblast activity, the cells responsible for building bone. With low estrogen, such as seen in a low energy availability state, bone breakdown may exceed bone building, causing decreased bone density. This is especially concerning for athletes, as low bone density increases the risk of a bone stress injury or stress reaction, an injury that depending on severity can take you out of training for weeks to months.


If you aren’t getting regular menstrual periods, and aren’t sure where to start, talk with your doctor or a medical professional. A primary care physician or OBGYN can help rule out any other diagnosis that may contribute to loss of period, and can order blood work and other tests to determine what course of action needs to be taken. FHA is often caused by a combination of things that may include excessive exercise, low body fat, disordered eating, and high stress among others. Therefore, a multidisciplinary approach including a dietician, psychologist, running coach, and medical doctor may be needed. It is important to note that the Endocrine Society Clinical Practice Guideline advises against the use of oral contraceptive pills to re-establish menses, as it does not protect bone density, and masks the occurrence of true “spontaneous” menses. (J Clin Endocrinol Metab, May 2017, 102(5):1413–1439)


When you get your period on time, you can know that your body has enough energy to menstruate, which is a good sign that you have enough energy for all other bodily functions. This means that you can train harder, recover more effectively, and ultimately perform better! I hope that this article can help you to understand the importance and power of a period.


Thanks for reading!

Dr. Elizabeth

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