Earlier this year, elite British runner Tina Muir shocked many in the sport when she announced that even though she was only 28 and at the peak of her fitness, she was putting her running career on hold. Not because she was injured. And not because she was no longer confident in her running ability.

Muir was taking a sabbatical from running because she had not had a period in more than nine years. She finally decided that was neither healthy nor normal.

Muir had amenorrhea, a condition characterized by the lack of a menstrual period. A girl who has never had a period before may be diagnosed with amenorrhea if she has not started menstruating by her 16th birthday. But the condition can strike at any age. A woman who has previously had a normal cycle might be diagnosed with it if she misses three periods or more in a row.

Technically, pregnancy causes amenorrhea. But for women who are not pregnant, breastfeeding, menopausal or younger than 16, amenorrhea is worrisome because it can not only affect a woman's future fertility, it can lead to a reduction in bone mass and an increased risk for osteoporosis. So while it may seem to some like a blessing to not have to worry about a period, it can wreak havoc on your future health.

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CRAAAAZZZYYYY how things can change in a year!! I wasn't sure whether to post this, feeling self conscious, and thought people might react negatively, but oh well, here's to being brave.πŸ™Š This time a year ago, I was about to run the #londonmarathon, I ended up smashing my PB of 2:41 to run a 2:37 and finish 2nd in the championship section of the race. I don't know how much I weighed, but I was in the best shape I had been in, both physically and mentally. One year later, and quite a few pounds heavier, I have not run in almost 5 weeks. But I CHOSE this. Last year I achieved some big goals, but now I have an even more important one, recovering from amenorrhea and getting my body ready for a family. I'm not gonna lie and say it's not hard looking at that photo and seeing me right now, BUT I am learning to love my curves, and I am definitely enjoying the food I am eating πŸ˜‹πŸ°πŸŽ‚πŸ¦πŸͺ🍩, allowing myself to let loose, rest, and heal after 14 years of complete dedication.πŸƒβ€β™€οΈ There are many ups and downs in every stage of life, but even in that moment, like that one on the left, I still wanted to look better, I still wasn't totally happy. I don't think we ever will be, all we can do is love our bodies and respect them. I know I am not "big" by any means, but this comparison shows the difference. My body has a new journey to embark on, and I plan to embrace it as best I can. I'm still me, right? *hesitates to push publish*.....aaaand GO

A post shared by Tina Muir (@tinamuir88) on

The primary symptom of amenorrhea is the absence of a period for three or more cycles, but the condition may also cause hair loss, headaches, an excessive production of facial hair, vision changes, breast discharge or a lack of breast development.

A lack of periods may be the body's way of sending out a distress signal to indicate a deeper health issue. Women who are most at risk of amenorrhea include those, like Muir, whose exercise regimen might be described as "intense." Women who are under extreme stress are at risk, as are women who are obese, have an eating disorder or have a family history of the condition. Amenorrhea may be caused by other health issues such as polycystic ovarian syndrome or genetic abnormalities.

According to the National Institutes of Health, you should contact your doctor after your first missed period, or if you are 16 but have not yet started menstruating. At that stage, your health care provider can start ruling out other conditions β€” such as pregnancy β€” that may be the cause. If your amenorrhea persists, it might be time to take a closer look at your diet and exercise routines to see how they might be affecting your body.

Sure, periods may be a drag. But as Muir found out, their absence is an even bigger hassle and one that can affect your health for years to come. The good news, as Muir also found out, is that amenorrhea is usually treatable. You may be surprised by just how good your body feels when your health has returned.

Amenorrhea: What is it, what causes it and when is it time to see a doctor?
Why worry about a few missed periods? Because amenorrhea could indicate bigger issues with your health.