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DrSugar Answers: Menstrual Fatigue and Exercise?

DrSugar is in the house and answering your questions.

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,


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!

If you have a question for DrSugar, send me a private message here, and I will forward it to the good doctor.

DrSugar's posts are for informational purposes only and should not be considered medical advice, diagnosis, or treatment recommendations. Click here for more details.

Join The Conversation
xlove33 xlove33 8 years
That was a terrible answer! I agree with insantiypepper, hormones are crazy! Completely against what is in my range of "normal," my last period started without my typical few days of anxiety-ridden pms which was nice, but i got the worst cramps ever on day one, then i got nausea on day two. It culminated in a migrane on the third day with the stressed out anxiety part of it arriving on the fourth... this is completely not normal for me and as you might conclude, it's been a rough week!! No two people are the same, and for many of us, no two cycles are even the same.
amntyler amntyler 8 years
Was there an answer in there? Why post a question and then not answer it? It's a waste of readers' time- not to mention the poor woman suffering from fatigue.
insanitypepper insanitypepper 8 years
I definitely get fatigue (and migraines and brain fog) when I'm on my period. Hormones can be so arbitrarily ruthless. I wouldn't put anything past them. But of course the other possible causes of fatigue should be checked out, too.
GlowingMoon GlowingMoon 8 years
"However, medically speaking, ovulation is not thought to be an adequate explanation of fatigue." Sorry, I think this is baloney. Personally speaking, my ovulation leads to fatigue. Actually, the right word is "weakness." It's a very distinct bout of overwhelming weakness that occurs when I ovulate. About ten days later, my period arrives. I'm wondering -- is this doctor male?? Maybe that's why he's dismissing menstrual fatigue. If this doctor was female, and experienced menstrual cycles, perhaps he would know it's a reality for some women, if not for himself.
lilCROAT03 lilCROAT03 8 years
when i have my p i sweat like 100 times more than normal.
nancita nancita 8 years
Wow, I had no idea fatigue was so difficult to diagnose. I have often felt it when I have PMS so I'm glad to know that is common.
Alithyra Alithyra 8 years
Based on personal experience and in NO way a medical opinion: Check out the thyroid levels. I complained to my doc about being fatigued all the time and she ordered a basic thyroid blood test. My level was low enough that I've been kicked over to a specialist for more tests.
sparklestar sparklestar 8 years
Conclusion - the internet can't help you with your medical problems, srsly.
aimeeb aimeeb 8 years
It's so hard to REALLY figure out the cause that I think they'll just have to change things here and there in their life and see if it helps. It's not something like rash where you know what will and won't help immediately on seeing it.
Marlovestar Marlovestar 8 years
The Dr.'s answer was not very helpful. Hopefully this person sees their primary soon.
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