Various people, including Willy Weir and the MEA purple book interpret the deteriorated result on the second CPET as 'an objective demonstration of PEM'. I strongly suspect that van Ness and Keller tend to think something like that too. But your PEM was over and done with.
Yes, it comes down to how PEM is defined. If we define it to mean the full-on symptoms, it's true, I didn't have PEM during the second test. However, my threshold of activity before symptoms occurred was lowered. On day 2 I had to walk to get lunch. It wasn't a huge walk and I took my time. On the way back, I really struggled. My legs became very heavy. I rested all afternoon and I didn't bother to go out for dinner, I just ate some snacks in my room. Yes,
@Invisible Woman, day 2 was a day of much lower activity than normal. In a normal day I can manage to do the household chores and walk the dog without 'really struggling'.
I'm inclined to think the lowered performance on the second test was reflective of some metabolic changes that meant that I could do much less before getting overt symptoms. There was that 3D graph by the Lights I think that showed the level of a number of cytokines on several days after activity for people with ME/CFS and controls. It showed that the impact of exercise in people with ME/CFS was very different to the controls. To me, that was quite compelling evidence of a biological process. I think Warren Tate may have been working to replicate it (indeed the study I took part in was supposed to analyse cytokines before and after, but in the end they didn't seem to have a budget for a nurse to take the blood samples). Maybe others elsewhere have replicated it?
If anything it looks as if the symptoms of PEM may be caused by some process that as a later knock on effect reduces anaerobic threshold. That is of course very consistent with an organic process involving immune system or nervous system or both.
Yes. Maybe we need another word to separate PEM and this 'later knock on effect that reduces anaerobic threshold'?
The 2 day CPET seems to show that one vigorous exercise is followed by a dip in function a day or two later. But there are situations where this occurs in normal people. After repeated exercise the effect goes away and the muscle gets more powerful.
What situations are these, where normal people show the same pattern? I'm not dreadfully unfit, my results showed that. And I believe that some studies have used sedentary controls.
That is of course very consistent with an organic process involving immune system or nervous system or both.
I very much go with go with that way of looking at things
Thank you.
we are still left with all sorts of vaguely possible alternatives routes to that, including ones that may be dependent on thoughts, either recent or in the distant past
I'm not sure how we counter that, without actually finding the physiological process. And, even then, the coverage of the psychological God of the Gaps just gets pushed back a little (as for cancer where people routinely blame stress and repressed emotions for the disease).
Do we need more Dubbo-like prospective studies where the psychological well-being of people is assessed before they even get ME? I think Jason's team was working on something like that in college students.
