PEM-like descriptions and accounts in non-ME illnesses

[Lou B Lou]

I have been looking into this topic for a while. The more I look, the more I find post-exertional malaise discussed in other conditions (and in healthy controls). I started a list here.

I see there are more references in this thread so it needs to be updated.

Note the Beyond ME/CFS IOM report discusses healthy controls having PEM. "The prevalence of PEM in healthy control subjects is considerably lower than in ME/CFS patients, ranging from 4 to 8 percent". Page 80 - https://www.ncbi.nlm.nih.gov/books/NBK274235/pdf/Bookshelf_NBK274235.pdf

The confusion about this symptom is another reason I prefer the International Consensus Criteria - post-exertional neuroimmune exhaustion that has a much more comprehensive description. I wrote about that here: https://colleensteckelmeiccinfo.substack.com/p/pem-is-not-equal-to-pene

'Note the Beyond ME/CFS IOM report discusses healthy controls having PEM. "The prevalence of PEM in healthy control subjects is considerably lower than in ME/CFS patients, ranging from 4 to 8 percent". Page 80 - https://www.ncbi.nlm.nih.gov/books/NBK274235/pdf/Bookshelf_NBK274235.pdf '


Healthy controls, by definition, do not get PEM. What waffle.

 

[JemPD]

yes.

I must say i am grateful for your posts Yann, I often think 'yes thats exactly like me' & it helps so much, especially with the stranger phenomena like this.

Just tagging you @Jesse as I know you asked about this kind of phenomena & whether others experience it. Just came across this oats from a while ago thought it might be of interest

Edited to add: sorry I quoted myself - I was replying to @Yann04 in post #25 I can’t work out how to add link or quote to that post now (it’s about what happens when push through)

 

[Utsikt]

@JemPD here are the posts in order. Yann responds to PL, and Jem responds to Yann.

I get PEM in what I call a few different arcs.

This sounds similar to one I get on good days.

On these days I can go out in my normal pacing level and might do a bit more. As long as I don't sit or lay down I feel ok. Soon as I sit down I feel aches and stiffness creeping into my muscles, I start yawning and feel tired or fuzzy headed. My body feels like it's yelling at me to not let people talk to me and it's time to lay down.

This passes after about an hour or so laying down (sleep not needed). I may or may not get a more delayed PEM fatigue the next day as well.

I have that too. Like a sort of if I keep on pushing it I can kind of ignore my symptoms, my body seems to pump adrenaline and I do okay. But it’s once I stop that activity and the adrenaline wears down I start feeling awful.

yes.

I must say i am grateful for your posts Yann, I often think 'yes thats exactly like me' & it helps so much, especially with the stranger phenomena like this.

 

[JemPD]

That’s awesome thanks @Utsikt - exactly what I was trying & failing to achieve.

Incidentally the world and his wife now experience “terrible PEM” because they feel tired after doing … whatever…

The term is nearly meaningless now.

Just like every cold is the flu, every headache is a migraine, every lapse in concentration or forgotten birthday is brain fog, every blue day is depression… all tiredness after activity is now PEM
<sigh>

Oh and of cpurse all ongoing fatigue is CF & thus ME/CFS

I hate social Media sometimes

I’d like to wallpaper the world with our factsheets

 

[rvallee]

S4ME thread: Postorgasmic Illness Syndrome: Insights from Recent Literature on a Rare but Fascinating Disorder, 2025, Wdowiak et al


News article linked in above thread:



Timeline and symptoms somewhat comparable to PEM.

I've seen enough descriptions of this from the LC community to be quite sure that at least a significant % this is indeed PEM. With medicine being both oblivious and in deep denial about the existence of PEM, it's also expected that they'd screw this up often.

 

[Mij]

I've seen enough descriptions of this from the LC community to be quite sure that at least a significant % this is indeed PEM. With medicine being both oblivious and in deep denial about the existence of PEM, it's also expected that they'd screw this up often.

I've seen many posts like this as well but have never come across one that describes the delayed PEM symptoms that I experience and recovery period that it takes from 3-10 days depending on how much we go over our energy limit.

It could be all related though.

 

[richie]

I think this is where the distinction between exercise-intolerance and exercise-inability becomes useful. Most of mitochondrial "PEM" I've read are the result of the conflating the two when it really resembles rapid fatiguability rather than PEM. The hallmark of PEM is that you are fine (not sick, that is) after an exertion and then get hit by the proverbial bus 12-48 hours later. It was like a clockwork when I was moderately sick: I'd be sitting up one minute, and then I'd get knocked out the next when 2PM rolled in. The post-exertional fatigue in mitochondrial dysfunction may carry, or even worsen, in the following days, but it does not involve precise delay/delineation AFAIK.

One way to separate PEM from PEM look-alikes would be to subject the patients to 2-day CPET test. If the patient can't reach VO2 max at the first place, then it's an exercise-inability. The ensuing fatigue or weakness should not be called PEM then.

Isn't demanding a delay for true PEM a definition by assertion? Even if there are key underlying biological differences among "PEMs" which should be considered cardinal in ME. Why does any one deserve to be the PEM of ME more than any other unless the other relates to a diagnosed differential condition?

 

[richie]

I've seen enough descriptions of this from the LC community to be quite sure that at least a significant % this is indeed PEM. With medicine being both oblivious and in deep denial about the existence of PEM, it's also expected that they'd screw this up often.

Have any studies in LC shown a 2 day CPET worsening. Last I read not. Reported bad sarcoid fatigue states sound like many ME accounts but no n trial has shown 2 day worsening. On the other hand a credible case could be made for be made for rapamycin to be trialled in sarc fatigue (may be not if active infection is suspected). Sub groups and overlaps maybe????

 

[Peter T]

Isn't demanding a delay for true PEM a definition by assertion? Even if there are key underlying biological differences among "PEMs" which should be considered cardinal in ME. Why does any one deserve to be the PEM of ME more than any other unless the other relates to a diagnosed differential condition?

We desperately need better descriptive data of what people diagnosed with ME/CFS or Long Covid experience.

However, though some people unambiguously describe PEM with little or no delay, it is easier to distinguish rapid fatiguability from PEM when there is a delay. What is importantly is the uniqueness of PEM such as the emergence of other symptoms like a sore throat or swollen glands or failure for rest to resolve it, with at times continued worsening over days or longer.

Certainly here people have described these abnormal or paradoxical features in immediate PEM, so I think we can not insist that immediate PEM is in some way qualitatively different to delayed PEM, but we perhaps need to look harder at immediate PEM than delayed PEM to be confident it is not just rapid fatiguability.

 

[poetinsf]

Isn't demanding a delay for true PEM a definition by assertion? Even if there are key underlying biological differences among "PEMs" which should be considered cardinal in ME. Why does any one deserve to be the PEM of ME more than any other unless the other relates to a diagnosed differential condition?

The PEM is defined as "worsening of symptoms 12-48 hours after the exertion" because it is observed as such, not by assertion. We don't know anything about the underlying biological process, so there is no point talking about the biology as part of the definition. The mitochondrial "PEM" does not fit that symptomatic definition. The worsening fatigue in mitochondrial dysfunction is gradual at best, and more likely immediate after exertion. That is why I was suggesting 2-day CPET test to see if its response to exertion resembles ME/CFS PEM.