Not sure what you mean by "fainting", but I thought we were talking about exhaustion. If you mean loss of consciousness, I'd guess that's a different symptom. If you mean immobilization, yeah, I'd think fatigue could immobilize. I remember being completely still for an hour or so once, in 2008 I believe. That never happened to me before or after.
I think from that detail we are talking about different things here. It's really hard trying isolate things under different terms, but it has flagged to me how the term 'exhaustion' is quite different to 'fatigue'. SO yes I'm talking about exhaustion and then entertaining whether it fit with your suggestion of exhaustion fitting that fatigue model you linked. And how exhaustion leads to those effects/symptoms. Which I don't think
is fatigue. But it's such a fuzzy term it has made itself Popper's theorem can't disprove it isn't because it morphs by being ambiguous. I'm happy to look at the paper but I for this reason don't think the terminology fatigue is anything other than unhelpful really for us. It's meaning is in the eye of the beholder.
Which I sort of knew in the way the BPS talked about the term fatigue that it was inaccurate to what we had, and when I discovered there was fatiguability made much more sense (I think they just misinterpreted what people were saying /or perhaps deliberately assumed what people said wasn't what they meant). I never had fatigue in the sense that you see those documents on 'managing fatigue' talk about where trying to chivvy your body along 'improves it'. I had the permanently forcing myself so knew all those tricks to have to perform despite yet it made it worse.
If i'd known about that mis-sell of what they meant by the term 'fatigue' at the time I'd never have used it. It's more ill-fitting than the term 'tired' which at least theoretically has the meaning that it is 'relative' ie 'that person is tired compared to their normal' so someone with severe ME could have had an appointment which tired them. Sad thing with that 'tired' term is how ambiguous it is and how normal people assume that how they feel when they've done something 'normal level of tiring' is what you mean. When they need to think proper emptying and hurting level of things like spending 5 days in transit on economy flights and in airport seats wide-awake with the odd snatch of sleep whilst hauling around heavy luggage. I don't think they would use the term 'fatigue' then either, but 'exhausted'. So I guess they are very different things because you can exhaust your supply of eg hairgel.
It is quite an interesting one to explore - because I think it might help to get to the bottom of explaining the misunderstanding of the condition. THe other usage of the term fatigue is eg in describing soldiers 'showing signs of fatigue' eg in their muscles or in cognitive tests for example with air traffic control to monitor the impact of fatigue on performance. In the sense of athletic training it might be used to describe someone who is back in training after eg a race just a few days before and is in their performance 'showing fatigue' vs 'exhaustion' being the theoretical phenomenon that is supposed to be temporary at the end of a 'leave it all on the track' race or training session.
So I guess fatigue could be described as a 'signal' where exhaustion is 'empty', but it is a very wooly term with a circular definition really (people know it is fatigue in athletes, soldiers, air traffic controllers
because their performance level drops
and the observer knows
what they've done) and can cover something
expected and normal. Whether they are describing utterly different things, and bunged together because in some situations you see them in close time sequence. I think it is interesting that other people note that one of the issues for PEM is that certainly when less severe your body lets you do too much/you don't ever know what that threshold moment was for PEM when you were doing it at the time (and it is cumulative), which I guess is what some of the newer apps are trying to work on giving people warning signals for.
What I'm not now 100% convinced of is whether fatigue is just an utter red herring which came about from lazy observation (lump and dump 'they all seem fatigued') where they weren't hearing the specific actual symptoms and timing of those from pwme but instead just thought it was 'fatigue' so only heard it was that. But that term is double-meaninged in itself it seems because fatigued could mean over-limit/needing rest
or that laypersons thinking you seem a bit lethargic or sleepy.
And it has been insightful to me because it has made me realise that it absolutely isn't a medical term at all. And just relates to normally 'relating something back to needing to take a break to recover or rejuvenate'. It is indeed 'expected' or seen as something that could be tackled. Exhaustion relates to an 'outcome' and sort of describes a hard threshold/state. That such a state can happen from what others mightn't even see as exertion (again others unbundling that term to note we use it because it
feels like an exertion) eg sitting up for long enough can lead to exhaustion is quite a specific term. I'm almost tempted to say I'm reticent to assume there is any fatigue to do with it at all/it's a red herring. I would get fatiguability where it would affect the quality of my speech for example
This is an interesting one for me to return to because I feel like it's sparked a few moments of thought for me, that will take time to try and unbundle and form. There is something about the term 'fatigue' assuming moveable thresholds and 'you can go into something fatigued already' being the purpose of it as a term, where fatiguability saying 'my threshold for x is y' and relating to exhaustion and signs of deterioration of perhaps both performance and health.
It doesn't help that these terms haven't been firmed up into being used in a precise terminology, and then you try and give good faith to any paper using them so are trying to read such terms and find the meaning they intended from them by looking into the methods etc.
On the other point - yes being immobilised is common (but I'd also split that down into very specific different ways too), but the fainting was an example of how it's 'ill' like 'exhausting yourself' when ill. So the concept I'm describing is like when (before ME) I had severe tonsilitis (not like most people had it understanding it as sore throat, but like one of the few who got really nasty tonisilitis) and then tried to have a shower too early and ended up having to give up as I'd gone utterly white and had to completely lie down. Fragile and collapsing. That's what happens, at pushing at the threshold and beyon when you shouldn't.