Can Overtraining Syndrome lead to ME/CFS? Hello everyone, I am new to the board. For the past 3.5 years, I've been struggling with irritable bowel (diarrhea), post exertional malaise and fatigue. My symptoms started to show up after I decided to join a weekend rec hockey league after many years of inactivity. I pushed myself really hard in the first game and noticed a change in my bowel habits after. Thinking it was nothing, I continued on for another 1.5 months (4 more games). I finally stopped when I noticed my bowel habits weren't improving. At first I didn't really notice fatigue or PEM, all I knew was that any sort of physical activity/exertion would worsen my bowel symptoms. But as time went on, fatigue and PEM started to creep up on me and I've noticed that worsening of my bowel symptoms were linked to fatigue. The more fatigued I am, the worse my D. My GI specialist thinks my irritable bowel is caused by an infection, but it was not something I believed in. I always felt my symptoms showed up after I started playing hockey. After much research, I've come across Overtraining Syndrome, which has changed bowel habits as one of their symptoms. Then PEM and fatigue research led me to ME/CFS. For the first time, I've found something out there that explains my symptoms. I haven't been officially diagnosed with ME/CFS but am in the process of seeing a doctor to get some tests done because my symptoms are getting worse. At the moment, I am trying to get as much research done as possible. One big question I have is, can Overtraining Syndrome become or cause ME/CFS? I've read through some of the posts on this forum and noticed a few members mentioned that their ME/CFS started off with Overtraining Syndrome, maybe they can chime in on this thread some more if possible? Thanks for all your input.