PEM discussion thread - post-exertional malaise

[jnmaciuch]

I was more so thinking about non-muscle microtrauma.

I think @Hutan mentioned elsewhere that deep tissue massage would be an option. I can’t say I’ve gotten any massages since becoming sick, so I can’t confirm or deny if it causes PEM.

 

[Jonathan Edwards]

I think it confirms that subjective sense of how much one has exerted is not causative in any way for the eventual development of PEM. It doesn’t matter how much activity my brain “thinks” I did.

But surely there is likely to be a difference between what you think you did and what certain parts of the brain think you did. Inferences in the brain go through many stages and the most accurate ones tend not to be the ones that we can give a conscious account of.

Because those of us who have experienced the milder end of the spectrum know quite well that PEM does not happen without actual activity.

But what about PEM after emotional or other mental events? In what sense does one know there is 'activity' other than the subjective sense that one did something.

I am afraid I find all these accounts inconsistent. Clearly I don't have the subjective experience to draw on but within the thread there are opinions all over the place it seems. And the task is to find something other than a subjective account of 'I know how it works', surely.

 

[Jonathan Edwards]

I have to object that calories per hour is a biologically coherent concept either. Calories in a biological context are inherently an estimation, not necessarily indicative of anything actually happening at the molecular level.

Absolutely.

I don’t think that the search for an objective marker of “exertion” will be fruitful, but not because it’s an empty concept—simply because it encompasses hundreds of various changes, any one of which individually is insufficient to represent the whole.

Which basically means that it is scientifically a useless concept? And that all we have is the subjective sense of 'doing'.

If what we are trying to pin down involves hundreds of various changes isn't it unlikely to be anything as simple as 'using energy' and much more dependent on signals that the body uses to tell itself that some rest might be needed to avoid injury - or something of that sort?

 

[jnmaciuch]

But surely there is likely to be a difference between what you think you did and what certain parts of the brain think you did. Inferences in the brain go through many stages and the most accurate ones tend not to be the ones that we can give a conscious account of.

sure, maybe. I don’t see any reason to invoke an unknown mechanism of “brain accounting” in PEM, though. We’ve been through this before, I don’t think it’s particularly useful to rehash.

But what about PEM after emotional or other mental events? In what sense does one know there is 'activity' other than the subjective sense that one did something.

We’ve hashed this out before as well. There are absolutely cognitive tasks that would be more metabolically demanding than others. And there are tons of ways for brain activity to lead to a biological state that needs to be recovered from even if it doesn’t look exactly like what’s happening in skeletal muscle.

If what we are trying to pin down involves hundreds of various changes isn't it unlikely to be anything as simple as 'using energy' and much more dependent on signals that the body uses to tell itself that some rest might be needed to avoid injury - or something of that sort?

I think people generally speak of using energy as a short hand for those hundreds of changes. Certainly signaling pathways are involved. But they are also signaling pathways that are directly intertwined with the processes of generating and using ATP and all the related upstream/downstream processes. The byproducts of metabolism are themselves the intermediaries of those signals in every single case.

So I agree that talk of using energy is overly simplistic if one is trying to use that term literally—but I don’t think anyone who has knowledge of metabolism is using it in that way. And I think it is a useful shorthand unless you want us to start listing processes involving several hundred metabolites every time I want to speak on the semantic concept of physical or cognitive activity.