DrSugar Answers: Menstrual Fatigue and Exercise?

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Hi DrSugar,
Last year I was busy training for my first triathlon, a half marathon, and cycling a lot for fun. Toward the end of my training, I would become extremely fatigued and often just pass out after work randomly a few days here and there. I had plenty of rest days, ate well balanced meals, and took vitamin supplements. I was tested for anemia but my blood iron levels were fine.

I'm in my off season and not training nearly as hard, but the fatigue is back. I was wondering, might this fatigue have something to do with my period? I am in between cycles, ovulating I suspect, but would that cause this type of fatigue?
— Why So Tired

To see what the doc has to say on this matter, read more.

I have found as a doctor that fatigue can be one of the most difficult symptoms to diagnose and manage. There are hundreds of potential causes of fatigue. Some causes are easy to detect with blood tests and iron counts as you mentioned, but some causes are much more difficult to diagnose. It is very common to blame fatigue on various points in the menstrual cycle, such as ovulation, menstruation, or premenstruation. However, medically speaking, ovulation is not thought to be an adequate explanation of fatigue. Some women do have fatigue associated with PMS, but it doesn’t sound like this is relevant to you.

Endurance runners, like you, are more prone to certain types of fatigue. Fatigue in endurance athletes is commonly due to over-exertion, dehydration, inadequate caloric intake, electrolyte imbalances, and hormonal imbalances. Other common causes of fatigue include depression, anxiety, anemia, infections, and drug or alcohol use or abuse. I would start by making sure you’re getting adequate hydration and nutrition. Once that is in place, then I would make sure you’re getting plenty of sleep and are taking occasional days off from exercise. If these efforts fail, it is time to see a doctor for further evaluation. It sounds like you had some basic blood work done in the past like iron levels, but there are many other blood tests that may be useful. Good luck!

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