Amenorrhea and exercise: does training have an impact on your menstrual cycle?

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No period, no problem? Think again, says strength and nutrition coach Pennie Varvarides. Your workout routine and menstrual cycle can impact each other more than you think.

I’m sure I’m not alone in regularly lamenting about my monthly cycle. The cramps, the mood swings, the endless anxiety that the moon cup might move during a heavy squat session. But sometimes the grass isn’t always greener. In fact, the disappearance of your cycle could be cause for alarm.

Amenorrhoea is the term for when there’s no menstruation - this is a symptom, rather than a diagnosis and could be caused by a number of things. And while having no period might sound like a good thing, it’s often a sign that there’s something wrong. If there’s more than 90 days between bleeds, you should consult your doctor.

There are numerous things that could lead to cycle disruptions; I’m going to focus on exercise and energy balance in this article. Training-induced amenorrhea is surprisingly common in athletes and can have some quite serious knock on effects.

A common cause of amenorrhea is a relative energy deficiency, in which your caloric intake is inadequate to the energy required to function. This can come about by either reducing caloric intake by too much or by increasing training volume by too much (or both).

Losing your period can result in your body mimicking symptoms of menopause in some women, including things like mood changes, cognitive problems and difficulty sleeping

A woman sleeping

Dr Sarah Murphy, Obstetric and gynaecology SHO, says: “Excessive exercise (along with disordered eating and psychological stress) can all cause amenorrhea, or absence of periods. This is known as hypothalamic amenorrhea.

“The body perceives these things as stresses and shuts down the reproductive hormones to compensate. Basically it tells a gland in the brain, the hypothalamus, to stop producing hormones. This will eventually feed to the ovaries and tell them to stop producing hormones, including oestrogen, and eventually lead to cessation of periods.”

The human body responds to the inadequate energy levels by finding ways to run off less energy. Ovulation and menstruation are essential for reproduction but not for day-to-day survival, and without enough energy, carrying a baby would be unviable - so it’s abandoned.

Dr Murphy adds: “Lack of these normal hormones can have some negative consequences. Firstly, oestrogen helps with normal bone health and growth. Without it, bones can become softer and reduce their bone mineral density, leading to things such as osteoporosis and potentially bone fractions.”

The prevalence of amenorrhea in elite athletes is reported to be as high as 65% in long-distance runners and 69% in dancers - compared with 2-5% in the general population.

GP Dr Michael Banna says: “Secondary amenorrhoea (which is when menstruation has previously occurred but has stopped) can be more common in women who exercise very intensely or who have a sudden increase in their exercise intensity, or rapid/excessive weight loss or low body fat levels.”

When amenorrhea is combined with low energy availability (not enough calories to support your body’s functions) and decreased bone mineral density, this is known as the female athlete triad. Low bone density is reported in 22-50% of elite female athletes compared with 12% of the general population.

This low bone density is important, because it increases an athlete’s risk of stress fracture. In fact, women with amenorrhea have a more-than two-fold increased risk.

Women actually create 92% of our total body bone mineral density by the time we turn 18 - with peak bone accrual between 11-14 years. This means that a lot of instances of osteoporosis in later life are often caused by a failure to obtain optimal BMD in childhood.

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The silver lining here is that athletes who do weight-baring sports have a 5-15% higher BMD than non-athletes. So for those of us who may not have had the best diet as teenagers (hands up over here), lifting weights is our best bet for protecting our bones as we get older.

So while overtraining and under-eating could lead to the loss of your cycle and bone density, weight training and adequate eating will lead to stronger bones.

Bone health isn’t the only worry when it comes to hormone imbalances. It can also have negative consequences with fertility and heart health.

Dr Murphy says: “Heart disease is increased in post menopausal women who also lack these hormones, however further studies are needed to show that this is also the case in pre-menopausal women with amenorrhea.”  

Fundamentals of strength: Hinge

Fixing your cycle

If your cycle has disappeared, step one is go and talk to your doctor. You need to make sure you’re getting appropriate help.

Hypothalamic amenorrhea is reversible. “Usually by removing the stress, eg reducing exercise, gaining weight, changing eating habits,” says Dr Murphy, “but this is best overseen by a doctor and dietician.”

There are numerous reasons for amenorrhea to occur, not just training and diet, so it’s important to speak to a medical professional to get it diagnosed. Your GP should always be your first port of call.

How long it takes to get your period back can vary, but don’t be surprised if it takes a few months.

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