Originally Posted by Electron

Personally I am very skeptical that this could be the cause. I have never heard of excessive exercise causing PN. Maybe it could contribute in some way, I just don't think it's likely. If you want to test it, just run less. I agree that toxicity and autoimmune attack sound reasonable, but there are many other causes. You are not around any toxins where you work, medications, scraping lead paint, etc.?

Ron