Because I see it as the central truth of the problem - and I doubt anyone will get anywhere until that is openly discussed.
If the problem is portrayed as simply an impossibility of action due to lack of energy resources then variability in ability makes no sense. If it is based on a complex inhibitory mechanism it makes perfect sense and restores ME/CFS to the world of real illness where we see that all the time.
This might all need a new thread, but let me throw a couple of thoughts into the mix.
Firstly, as I see it there are two very different barriers to exertion:
1.
In the moment Fatiguability.
This is similar to a proper exhaustion, in that it feels like the body can literally do no more. An extra shot of adrenalin, might give a bit extra, but only on the very short term.
2.
The problem of PEM/PESE.
This is the more frightening one, because letting PEM happen can mean a permanent downturn of the illness trajectory.
In my experience, these two barriers to exertion can feature differently at points in the illness timeline.
When I was first ill, I allowed myself to keep doing stuff until fatiguability hit, but I quickly learned that the after-effects were not good. So I started to pull back before fatiguing set in.
In my first 4 years of having ME, I was constantly having to do less and less to prevent PEM, and the inevitable ratcheting downwards that I experienced afterwards. So I started to pace much more carefully. I was rarely “tired” because I always stopped well short of any fatiguing if at all possible. I disliked being in situations where I wasn’t in full control of what was going on. In truth, I was on a very scary downwards trajectory.
At the start of my 5th year ill, things changed. (It’s no secret that I took Viread/Tenofovir, and that I give it full credit for my turnaround… n=1 and all that. Sadly, others did not do so well on it.)
Anyway after that point, my PEM threshold improved. I became able to DO more, and so I became able to allow some fatiguing before having to pace myself. So the emphasis became different.
I think any discussion of the physical limitations of ME needs to account for both Fatiguability AND PEM, because in my experience they are very different beasts. And a pwme pacing to avoid PEM could of course look as though they are exhibiting a purely voluntary “avoidance” behaviour. As we all know of course, it is a learned behaviour though to avoid deterioration due to PEM.
Yet I also wonder do we need another PEM category? PEM+D
ie PEM that is always followed by Deterioration?
Because at one point that is what I had, and what I have heard others describing when they are on a spiralling downwards trajectory.
At that time, I often felt that PEM alone to “pay for” a nice activity might be okay, if I could guarantee I wouldn’t lose any functioning with the PEM. At that time my PEM always seemed to have the +D bit added.
Now that I am less unwell, my PEM happens less severely, and without the +D bit, which is obviously the scary, scary part. I can take more risks now (still calculated of course).
So I think what I’m trying to suggest is that there might well be more than one process involved in what limits the exertions of pwme. Johnathan, I appreciate you trying to understand all this. It isn’t easy to get my head around even after living with ME for 12 years now.
Anyway, sorry that this pulls things off topic. I have been following this thread, and fully appreciate everyone who is contributing to it.