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How exercise can shut down women's periods — with dire health consequences

Gymnasts are among the higher risk groups of "female athlete triad" syndrome.
Gymnasts are among the higher risk groups of "female athlete triad" syndrome.

We don’t usually hear much about women’s periods during the Olympics. That is, until Chinese swimming phenomenon Fu Yuanhui broke the silence last week in Rio and brought up her menstrual flow following a fourth-place finish.

"My period started last night," she told a Chinese journalist, "and I'm feeling pretty weak and really tired right now."

But it’s not just Fu who’s opening up. The medical community and even the International Olympic Committee are becoming more comfortable talking about a number of issues around training, competing, and periods — some of which can put women’s health at grave risk.

One particular concern: As the number of female elite athletes has skyrocketed in the past 25 years, researchers say women are at risk of the "female athlete triad" — a spectrum of conditions that include low calorie intake, missed periods, and loss of bone density.

An estimated 25 percent of female elite athletes report chronically missing their periods, and some analyses of ballerinas and long-distance runners suggest the problem is even more prevalent in those groups.

Fu Yuanhui at the Rio Games.

The potential long-term health consequences of the triad are dire: increased risk of osteoporosis and bone fractures, heart attacks, infertility, and vaginal and breast atrophy.

Yet few athletes know about the syndrome, even those who are at highest risk, which means it can often go unnoticed. "Historically, many of these athletes have been cleared for sport participation without appropriate evaluation, management and treatment," wrote sports medicine experts in a consensus statement, endorsed by the International Olympic Committee, on treating women with the triad.

That’s why doctors and sports medicine experts have been trying to draw attention to the impact intense training can have on women’s health. And that’s why it’s significant when elite female athletes like Fu open up and make talking about periods less taboo.

It’s not just extreme exercise that causes some athletes to miss their periods

While exercise is hugely beneficial for just about every health outcome, extreme exercise — particularly when coupled with eating too few calories to compensate for all that energy burn — can have negative health consequences for women’s bodies.

One of the hallmark features of an imbalance in female athletes is amenorrhea, the clinical term for missing at least three menstrual cycles in a row.

The most common cause of amenorrhea is pregnancy, according to the Mayo Clinic. But another major risk factor is athletic training.

"The exercise does not have to be extreme; there just has to be an energy imbalance, so not enough calories in to support the demands of exercise," explained Kate Berz, a sports medicine doctor at Cincinnati Children’s Hospital, who works with athletes with amenorrhea and other features of the triad.

When athletes eat too little during training and the body goes into starvation mode, it disrupts the release of reproduction-related hormones from the hypothalamus (the gland that regulates bodily functions). "This causes a cascade of missed signals through the pituitary gland and ovaries that results in less estrogen available to build strong bones," Berz said.

In red, the three related components of the female athlete triad: Eating too little affects menstrual status, and in turn, calorie availability and menstrual status influence bone health. In green, optimal health is indicated by adequate energy availability, regular periods (eumenorrhea), and good bone health.
British Journal of Sports Medicine

In evolutionary terms, you could think about it like this: The female body shuts down its reproductive capacity to protect from becoming pregnant, since it barely has enough energy to carry out its own basic functions.

According to UpToDate, the evidence-based encyclopedia for clinicians, the likelihood that a female athlete will start missing her periods is also determined by the type and quantity of exercise. "Activities that tend to be associated with low body weight (eg, running, ballet dancing) and sports in which scoring is subjective (eg, figure skating or gymnastics) are associated with a higher incidence of amenorrhea than are other activities such as swimming," UpToDate reports.

What’s more, there’s an association with how quickly a woman ramps up her exercise routine: "Gradually increasing exercise is less likely to be associated with amenorrhea than are more acute increases, such as when a woman quickly increases training for a competition."

Some women’s bodies can respond to exercise and metabolic stress better than others, and researchers think differences in genetics and hormonal responses determine whether a female athlete is likely to miss her periods.

The longer-term consequences of the triad can be serious

Because exercise-induced amenorrhea messes with the production of reproductive hormones, athletes with the condition tend to be estrogen-deficient. This can bring about a host of other health problems, including infertility and the thinning and drying of the vaginal walls, as well as breast shrinkage.

Women with amenorrhea often have decreased bone density and face an increased risk of osteoporosis and bone injuries. (Women can lose an estimated 2 to 3 percent of bone mass per year if left untreated.) As Berz noted, "Sometimes the first sign of the triad is a stress fracture or bone injury."

They’re also at a greater risk of cardiovascular complications, like high cholesterol, and heart attacks later in life. That’s why doctors warn that treating the triad "can prevent a potentially life-threatening illness."

The treatment is simple (at least in theory)

The best treatment is rather simple, at least in theory: getting athletes to eat more and cut back on exercise, or eat enough to compensate for all the energy they’re burning off while training, until their periods return.

"Sometimes the patient does not realize that she is not eating enough to support her exercise routine, and it is as simple as adding in an egg or spoonful of peanut butter at each meal, [or] changing from skim to whole milk and yogurt," said Berz.

This approach is extremely effective. As the consensus statement on the triad noted, women who start to increase their energy intake and reduce training by as little as one day per week typically get their periods again within a few months. And when menstruation starts again, women see improvements in other health outcomes, like bone density.

But of course, actually getting athletes onto treatment can be tricky, especially for those who do aesthetic sports like gymnastics, which require them to maintain a particular weight. And if the athlete is suffering from an eating disorder, like anorexia or bulimia, psychological and pharmaceutical treatments may be needed.

As this 2012 journal article explained, "Athletes are often determined, competitive people, with perfectionist personalities. Changing their mentality and altering their regimen of diet and exercise can be quite difficult." So one of the greatest barriers to treating women with the triad, the authors write, is "overcoming the psychological component of their condition."

"It often takes a multidisciplinary team to treat this condition," Berz added. "The team includes the patient, friends, family, coaches, athletic trainers, nutritionists, psychologists, and physicians."

Some elite athletes say getting their period can affect their performance

British tennis champ Heather Watson once attributed her poor performance to "girl things."
(Photo by Rich Linley/CameraSport via Getty Images)

In addition to the negative impact training can have on the menstrual cycle, there’s the opposite problem — how the menstrual cycle can impact athletic performance.

Like Fu Yuanhui, the British tennis champ Heather Watson attributed her loss in the first round of at the 2015 Australian Open to "girl things."

These women are certainly not alone. A recent survey of elite athletes published in the journal PLOS found that 51 percent reported their menstrual cycle had an impact on their training and performance. One hypothesis is that women can lose a lot of blood, and iron, during their period, putting them into an anemic state, which would reduce endurance.

But researchers don’t fully understand the mechanisms at play and have called for more study of the menstrual cycles of athletes.

More awareness about the issue is certainly a step in the right direction, and statements like Fu’s are a sign we’re heading toward lifting the taboo. Not only will this be good for women athletes who have long suffered in silence, it’ll also be good for their health.

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