PEM discussion thread - post-exertional malaise

[Sean]

The loss of function is not due to the increase in symptoms, but due to the threshold for triggering more PEM being lowered

The lowering of the threshold is an important factor.

––––––

The sometimes extreme loss of function via PEM may or may not be classed as a symptom. But that it happens, and how seriously it affects basic operating capacity in daily life, is a very important thing to get the world to understand.

 

[Utsikt]

on the other hand, you are sick 24x7 with 90% of functioning already lost. PEM days are then only worse than usual.

I disagree, PEM days are a lot worse when severe or worse, because they cause you to need more help immediately. There is nothing to cut back on, that you don’t need to survive.

So PEM might take you from 3 % of functioning to 1 %. And while that’s just two percentage points, it’s also 67 % of your functioning!

 

[Lou B Lou]

This post and the following discussion have been moved from:
Three part article on cognitive therapies, mindfulness, Garner etc., 2025, Long Covid Advocacy Substack article

@poetinsf wrote:
"You could get stress out by misbehaving people and end up with PEM (I don't know the "violent anger issues" that @Utsikt was referring, I'm making this up). By simply observing it as a phenomenon rather than reacting, you can prevent PEM."


You seem stuck on the erroneous idea that stress is the prime cause of PEM, and preventing PEM by not getting stressed.

The reason people with ME find driving demanding is not stress. It's the physical activity/energy requirements, complex co- ordination, and the extreme cognitive demands of continuous processing of vast amounts of continuous information on the road. Visual and auditory information, and the complexity of constant adjustment to changing conditions required to drive at all, let alone safely.

Many people with ME can no longer drive at all for those reasons, let alone drive safely.

Being faced with a road rage incident simply adds on another layer of information to process while operating possibly at the limits of what the person with ME can cognitively process.

Perhaps you think that ME is a stress condition.


PS - I practiced meditation of all kinds, including mindfulness, plus yoga, yoga nidra etc, since 1972.
None of that prevented me from becoming sick with ME following a virus infection in 1995. Meditation/mindfulness didn't cure me either.
Many people with ME are veterans of meditation/mindfulness (since way way before Kabat-Zinn and the rest took it up).
Mindfulness didn't prevent them from becoming sick with ME, and didn't cure them either.

.

 

[poetinsf]

You seem stuck on the erroneous idea that stress is the prime cause of PEM, and preventing PEM by not getting stressed.

Exertion is the cause of PEM, but some people have reported stress as a trigger. If you think about it, stress, either physical or mental, is a form of exertion.

 

[Utsikt]

Exertion is the cause of PEM,

We don’t know that.

but some people have reported stress as a trigger. If you think about it, stress, either physical or mental, is a form of exertion.

Can you define exertion in terms of the biological processes involved?

 

[Hoopoe]

Brain activity is the exertion. Being exposed to a complex environment with many different things going on, music, people, and so on is exertion, even if the person is just sitting there. The brain has to process all this and when it's fatiguable it won't be able to do it for long. As it becomes tired, it will become distractible and the person will try to withdraw, either mentally by intentionally paying less attention to the outside world, or physically by seeking a quiet place.

Physical activity also involves brain activity. The balance has to be kept, the muscles coordinated, the eyes must track things, the brain must analyze what it seems and so on.

I notice that different parts of the body have their own exertion limits. When one part is exhausted, another may still have some reserves.

 

[Midnattsol]

We don’t know that.

Can you define exertion in terms of the biological processes involved?

Anything that needs an organism/cell to adapt to it? Some cells react to sound, some to heat, some to touch etc. It all has to be processed in some way.

 

[Utsikt]

Anything that needs an organism/cell to adapt to it? Some cells react to sound, some to heat, some to touch etc. It all has to be processed in some way.

Wouldn’t that make literally anything that happens to our body «exertion»?

And isn’t it more or a reaction than an adaptation?

 

[poetinsf]

Can you define exertion in terms of the biological processes involved?

Spending calories to move muscle or fire neurons. Will that work?

 

[Utsikt]

Spending calories to move muscle or fire neurons. Will that work?

Literally everything costs energy, though. So if costing energy = exertion, and exertion causes PEM, we’re at everything causes PEM.

 

[Jonathan Edwards]

Spending calories to move muscle or fire neurons.

Looking at the dictionary definitions, exertion isn't really to do with expending energy or being active.

It means making an effort, or applying a force (which potentially requires no energy if there is no movement even if in biological systems it usually does).

It certainly isn't a stimulus or stressor, as far as I can see.

It involves doing which is a difficult concept because it is tied up with agency and we don't understand agency well. Until we do, I suspect exertion is not a term that can be used in a scientific theory beyond the reference to some subjective sense that someone has made an effort.

I think there is quite a serious problem here because PEM is central to arguments about the causation of MECFS but the exertion bit is highly ambiguous and very open to misinterpretation. Lots of people seem to assume that it implies using energy or being active. If so, it is likely the wrong word.

 

[EndME]

Literally everything costs energy, though. So if costing energy = exertion, and exertion causes PEM, we’re at everything causes PEM.

Similarly you can't stop your neurons from firing, they always fire. One has to be careful with arguments such as "PEM is a consequence of spending calories or neurons firing". One ends up in the vague BPS land very quickly without any meaning.

 

[Midnattsol]

Wouldn’t that make literally anything that happens to our body «exertion»?

And isn’t it more or a reaction than an adaptation?

I’m a cell biologist at heart, everything in our environment can cause the cell to have to exert itself to maintain functioning. For example I think my body is exerting itself trying to maintain an adequate blood pressure in the heat we’ve had where I live right now. Similarly I find it streneous to listen to traffic/building noise, and when in PEM it is downright painful.

The semantics of react or adapt in this context doesn’t make much sense to me, a reaction is often to try to function in a specific context/adapt to input no?

 

[Utsikt]

I’m a cell biologist at heart, everything in our environment can cause the cell to have to exert itself to maintain functioning. For example I think my body is exerting itself trying to maintain an adequate blood pressure in the heat we’ve had where I live right now. Similarly I find it streneous to listen to traffic/building noise, and when in PEM it is downright painful.

The semantics of react or adapt in this context doesn’t make much sense to me, a reaction is often to try to function in a specific context/adapt to input no?

To me, adaptation is an abstract concept that can only be used about systems. It also usually implies agency.

The cell isn’t «trying to function», it’s individual atoms and molecules are just reacting according to the laws of physics, etc. (although you probably have to get down to the quantum mechanics at some point).

Essentially, it’s the same issue as JE described above with regards to exertion.

 

[Midnattsol]

The cell isn’t «trying to function», it’s individual atoms and molecules are just reacting according to the laws of physics, etc. (although you probably have to get down to the quantum mechanics at some point).

To me we humans are also just reacting to our environment, be it physics or more abstract social stuff (I don’t believe much if any in free will, but in day-to-day that doesn’t really matter). I do believe «anything» can cause PEM, partly as that is my own experience and partly as that is how I interpret it when I hear someone say exertion and the inclusion of different kinds of exertion like physical, cognitive and emotional in others’ stories (so yes we are going in circles on the meaning of the words).

I struggle to understand why it is problematic to say everything can potentially cause PEM. To me it sounds like arguments I hear when someone has food allergies and are being told it’s impossible that there are so many foods they cannot eat (and how can it possibly be made worse by exertion*, seasons** or suddenly appear in adulthood*** etc etc)

*exercise induced food allergies (most known with wheat)
**food allergies made worse by say pollen allergy
***meat allergy from tick bites

Edit to add: Migraines are another thing that can be caused by «anything». Physical activity was one of my triggers. Together with sensory inputs. The noise sensitivity I have with PEM feels similar to the one I had when I had a migraine attack.

 

[bobbler]

Looking at the dictionary definitions, exertion isn't really to do with expending energy or being active.

It means making an effort, or applying a force (which potentially requires no energy if there is no movement even if in biological systems it usually does).

It certainly isn't a stimulus or stressor, as far as I can see.

It involves doing which is a difficult concept because it is tied up with agency and we don't understand agency well. Until we do, I suspect exertion is not a term that can be used in a scientific theory beyond the reference to some subjective sense that someone has made an effort.

I think there is quite a serious problem here because PEM is central to arguments about the causation of MECFS but the exertion bit is highly ambiguous and very open to misinterpretation. Lots of people seem to assume that it implies using energy or being active. If so, it is likely the wrong word.

It’s hard because eg I’m feeling awful today from a calendar last week that means this isn’t surprising

So today just getting my medication involves much more than on a day of at a time where I’m less in PEM

I’m curious to know (would an app tell us) whether and what terms we use for example if I managed to brush my teeth the exact same way (same amount of sitting up, arm hold or movement) on a day like today vs a day where I feel less awful then is that a different thing.

I also don’t know whether for example with the ‘you aren’t unfit but have me/cfs’ point that means that if when more well I could do a pretty swift 800m walk going to a meeting vs lolloping it slowly did it make a difference on either the PEM I had later or the overall deterioration over time of my me/cfs. Or was it just the having to walk the 800m at all that did it. Ie are fit people at more risk of more pen/deterioration because they could ‘do more’ without realising it was ‘exertion’ at the time

You’d think I’d have the answers to these questions but of course it takes a lot of thinking because across different jobs and different periods these things came in packages. So for example I’d not just walked that day but had 25phone calls and questions in person at the same time whilst also trying to do other work. Or maybe some days I didn’t and had a calm organised workload without interruptions but had that walk (but how much did earlier days carry over). And whilst I got continual worsening calf and shin pain and disappearing lower legs as eg car parks moved further from office the ‘central’ impact of said exertion would somewhat I assume all overlap with the sensory and cognitive and orthostatic to just be me not being able to wake up or move

I think these app tech things could be really helpful if they work closely to work out how to differentiate these things and concepts. If you find it easy to reel off a sheet of complex maths for example does the exertion end up the same as someone who found it excruciatingly hard to do said maths

All of these things now of course lurk around the things normal people consider basic but are some of the most taxing tasks like tooth brushing or showering

 

[poetinsf]

Literally everything costs energy, though. So if costing energy = exertion, and exertion causes PEM, we’re at everything causes PEM.

But exertion is not what causes PEM. Your low threshold for exertion is. So, severely ill patients could be in constant state of PEM just by being alive and breathing while it takes running up a hill for a recovering patient.

 

[Utsikt]

But exertion is not what causes PEM. Your low threshold for exertion is. So, severely ill patients could be in constant state of PEM just by being alive and breathing while it takes running up a hill for a recovering patient.

A lowered threshold for exertion/activity isn’t the cause of PEM, it’s a result of PEM. We don’t know what PEM actually is yet.

 

[poetinsf]

Looking at the dictionary definitions, exertion isn't really to do with expending energy or being active.

I just googled and the dictionary says "physical or mental effort". Unless you are talking about BPS-type effort preference, effort in everyday sense means expending energy. Effort preference, btw, is not the cause of (delayed) PEM as far as I understood. It is the cause of fatigue.

It involves doing which is a difficult concept because it is tied up with agency and we don't understand agency well. Until we do, I suspect exertion is not a term that can be used in a scientific theory beyond the reference to some subjective sense that someone has made an effort.

To make it simple, we could limit the concept of exertion only in relation to PEM rather than fatigue or anything else. Does agency or consciousness/subconsciousness play role in PEM? The answer would be a resounding no if you ask patients. Certainly not in my experiences with PEM. I could always trace back to physical exertion for my PEM, like walking too fast. Precise prediction is a bit more difficult because the difficulty of measuring exertion and how it is applied. My model using overall cal/min measured with fitbit however does predict with 10-40% accuracy. Maybe that's nothing to write home about. (If it were I'd have published it). but it is nothing to sneeze at either when all other models based on other physiological measures shows zero correlation. It sticks out like a sore thumb in the land of noises.

I think there is quite a serious problem here because PEM is central to arguments about the causation of MECFS but the exertion bit is highly ambiguous and very open to misinterpretation.

I think that's why we should stick to purely physical definition of exertion so as not to open it to misinterpretation.

 

[Jonathan Edwards]

I just googled and the dictionary says "physical or mental effort". Unless you are talking about BPS-type effort preference, effort in everyday sense means expending energy.

No it doesn't. People know what effort is even if they have no idea what 'expending energy' might mean. Expending energy is just a lay metaphorical term anyway for 'doing stuff'. The lay sense of energy is something like 'brio' - feeling full of beans. You don't expend that, even if at the eend of a marathon it is gone. We wil get nowhere if we talk of energy in this colloquial way.