I'm still looking for references which would show either that a drop in anaerobic threshold lasting 24 hours or more after exercise was either known or not known in prior medical literature of any condition. (I already know about overtraining syndrome in athletes.) If this shows up in any pathological situation we have good reason to call for research into this aspect of the pathology of ME/CFS. If it does not, we have reason to ask why medical testing has just now gotten around to asking if assumptions about the benefits of exercise in all contexts are true. For those wedded to biopsychosocial models, I have to ask how patients whose "perceptions" of the threshold at which exercise becomes destructive are screwed up can tell they are approaching these limits prior to waking up in the emergency department -- an experience I and some others here have had. Telling us we "have to push ourselves", but not, of course, "too hard" is not useful. If I wanted generic medical advice, I could listen to Dr. Oz more cheaply. We have been paying for personalized expert advice, unless disability and poverty have forced society to pay our doctors. By and large, this is not what either we or society have been getting for the money. We need research criteria for such thresholds, and we need proxies for these measurements patients can use in everyday life. We also need recognition that normal maintenance activities to keep food, drink and/or medication in us, and clean clothes on us, or to arrive at therapy sessions with some idea of where we are and what we are doing, consume energy from a fixed budget which many researchers are at some pains to avoid measuring. (Consider the way PACE dropped actigraphy.) For progress to take place, we need someone to actually investigate patient reports of exercise intolerance, orthostatic intolerance, dysautonomia, weakness, dizziness, etc. At that point we can began to do something about more subtle problems like episodic cognitive impairment ("brain fog") and/or emotional lability. Current practice has the cart before the horse.