What could it mean biologically that both physical and cognitive exertion can cause PEM?

[Snow Leopard]

That’s definitely something I’m interested in.

There is a phenomena known as sympathetic sprouting, post neurological injury, there is coupling of afferent (sensory) nerves with downstream efferent sympathetic nerves. This helps aid neurological recovery but can also lead to altered sensitisation of those nerves.

Obviously this requires actual nerve injury in the DRG as a pathological mechanism. This is one of my working hypotheses and there is evidence of DRG involvement in autopsy cases in the UK for example.

"Sympathetic sprouting near sensory neurons after nerve injury occurs preferentially on spontaneously active cells and is reduced by early nerve block"

Sympathetic sprouting near sensory neurons after nerve injury occurs preferentially on spontaneously active cells and is reduced by early nerve block - PMC

Some chronic pain conditions are maintained or enhanced by sympathetic activity. In animal models of pathological pain, abnormal sprouting of sympathetic fibers around large- and medium-size sensory neurons is observed in dorsal root ganglia (DRG). ...

pmc.ncbi.nlm.nih.gov

 

[bobbler]

I've always wondered how come both physical and cognitive exertion can cause PEM. I'd have thought that moving around would have used very different biological mechanisms and energy expenditures than thinking, on the whole.

There has been talk of 'emotional exertion' causing PEM, even though emotions don't really seem to fit the bill as 'exertion'.

I also wonder whether PwME who have OI and simply remain upright for too long can have PEM (I suspect I can).

Does it indicate anything about the mechanism of ME/CFS that both physical and cognitive exertion can cause PEM?

Is it worth trying to clearly identify other possible triggers of PEM to help point at mechanism?

@Jonathan Edwards (As always!)

Is it really that different in what is needed for cognitive vs physical exertion?

Most tasks involve some overlap eh sitting up to type or thinking where to run

Talking and the different levels of conversation depth and mediums is the classic both one. It’s pretty physical when you get iller it’s obvious how physical it is. And the word finding feels like an activity in itself vs thinking if your considered answer to the point it becomes impossible to do both at first (so you can’t consideration want to answer with words in good time), then both so you end up just saying whatever words have been out in your moth. Intuitively manybonlookers know this, see it and use it which is why I’m puzzled when the same nefarious types who take advantage that way obviously see our buttons to push but are the worst fir then claiming they don’t see them exist.

And both systems need an energy supply.

With physical exertion you have more muscles involved yes but different exertions it is different muscles.

I note I can get localized impacts eg fatigue ability in arms. But there is something central which sometimes is as much to do with being upright as well, and still now in the moment if no chair then moving is better than just standing even though both leave me harmed.

Doesn’t most ‘work’ involve certain common things in physiology?

And yes maybe there’s some interesting stuff to be had if you take the experience/knowledge of those who’ve been more severe so learned how to eg read or think whilst minimising other physical things like sitting up most would naturally do at the same time , but train some of those less ill to do those. Because that less ill group might then be able to see the difference if those activities are ‘almost pure cognitive’ where even that 10% from typing or moving a mouse is a lot for more severe. And the discomfort they might be carrying anyway etc.

And then see if their symptoms specifically to just that vary significantly vs physical but somehow with no music and no thinking. But what do you do about the orthostatic and temperature etc there - I guess just starting is a start (but noting those other factors so if someone in another part of the world gets a different result we can see that it was 10C hotter)

 

[Snow Leopard]

And yes maybe there’s some interesting stuff to be had if you take the experience/knowledge of those who’ve been more severe so learned how to eg read or think whilst minimising other physical things like sitting up most would naturally do at the same time , but train some of those less ill to do those. Because that less ill group might then be able to see the difference if those activities are ‘almost pure cognitive’ where even that 10% from typing or moving a mouse is a lot for more severe. And the discomfort they might be carrying anyway etc.

I wonder about this too, usually cognitive activity can have additional physical/orthostatic demands at the same time so there sort of needs to be a control (doing the same activity but without the cognitive demand).

But I think there is something there with regards to autonomic symptoms, those who report cognitive activity causing physical PEM seem to have more severe autonomic symptoms in general, I think this is something that needs studying.