My CFS started at age 30 with acute mononucleosis (showed up in bloodwork). I have a CFS diagnosis from several hospitals, according to the Canadian criteria, and some of the “typical” lab abnormalities (e.g. very low NK-cell number & function, low IgG subclasses,..). However, I’ve always been wondering whether my PEM is somewhat untypical for CFS, or whether I just find a different way to describe it. Sometimes, when I read stories from other patients, I am under the impression that they (at least those who are moderately affected like me) can actually (in theory) do sports, but will crash the next day and lie in bed for the next month or so. My perception of PEM is so different… Once my hr goes beyond a certain threshold (around my AT I suppose) for more than a couple of minutes, I feel horrible. No delayed response, the symptoms usually come within MINUTES (I envy those who can at least enjoy their activities although they have to pay later..). Horribly exhaustion - and apart from that, the term “flu-like symptoms” sums it up pretty well. Usually my lymph nodes get tender, but the worst thing is that I feel like a have a huge fever. When I stop and allow my hr to go down, it takes everything between minutes and weeks to recover. If I’m lucky, I will sit down for the next three hours and still prepare dinner afterwards. Normally, I’d just lie on the couch the rest of the day, and feel pretty much “recovered” (at my “normal” symptom level) the next day, being able to repeat the whole story. Sometimes, and this happens with both physical and emotional exhaustion (e.g. a huge fight), it will take weeks though until I get back to where I was before the activity. Lately, I tried some winter sports (what was I thinking..?), crashed the same day (with the symptoms kicking in after a couple of minutes, as usual), and was able to do a lot less for the next 14 days, with higher temperature than usual (sub-febrile), more flu-like-symptoms (sore throat, feeling feverish, swollen lymph nodes etc.) more pain, and substantially more fatigue. Is my PEM weird? Or pretty normal? Am I the only one who can link symptom increase to heart rate in such a direct way? Am I the only one who doesn't have a delayed response to activity? "Exercise intolerance" is my biggest problem tbh, both because it restricts me in everything (can't work but a tiny little bit from home), and because of the emotional aspect.