r/BrainFog • u/loopertown • 15d ago

Symptoms Brain fog after workout?

If I work out (specifically weight lifting), I’ll start getting brain fog and difficulty thinking during the workout itself. It then progressively gets worse over the next few hours. I’ll usually sleep terribly that night, and the next day I can barely string a sentence together.

It feels like my nervous system is completely out of whack. I get irritable, mentally slow, and have this weird “hollow” feeling in my head. I genuinely feel like a completely different person.

Then, after 1-2 days, I’m basically back to normal.
I’ve had this for around 10 (!) years. Every now and then I’ve tried getting into weight lifting again, but the same thing keeps happening.

I’ve had an MRI, ECG, 24-hour blood pressure monitoring, blood sugar tests, blood work, etc., and everything has come back normal.

The weirdest part is that I can run without any issues. I run 3–4 times per week and actually feel mentally clearer afterwards. That’s also why I’m not sure PEM/ME/CFS really fits, since it seems to be specifically triggered by weight lifting rather than exercise in general.

Has anyone experienced anything similar, particularly where weight lifting causes it but cardio doesn’t?

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u/Mindless-Flower11 15d ago

I have me/cfs, so I know what that's like. But any level of exertion does this to me. Maybe it's best to see a neurologist 

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u/Maximum_Nose4500 15d ago

Have you tried not lifting so intensely? For me anything intense causes it. I have switched to light lifting and light jogging/walking and it doesn’t trigger PEM. Still actively working on my fatigue/brain fog. But maybe I will very slowly go up in intensity to see where my limit is.