Cardiopulmonary Exercise Test Results Do Not Change Over Two Sequential Days in Patients with Chronic Fatigue Syndrome, 2026, Mancini, Natelson et al

[richie]

It’s disappointing for me to see how scientific data that I thought was robust about out illness is actually much more shaky. I think it comes with the learning phases of how research and replication work, but it still sucks.

I’ve held onto the CPET and mitochondria data to explain my illness to myself and other people, and it seems to be less of the case. But telling people about an unknown neurological problem is not very convincing to earn their sympathy and respect.

It feels like SequenceME is my main hope for an explanation. I’ll hold onto that for now.

But these tests for you may be fair and square. I wouldn't give yourself any grief at this stage.

 

[richie]

I’m severe so the idea of these tests always sound completely alien to me. However before being ill I would run, push myself, have a high heart rate and after it would drop and I’d feel tired but also good. Since being ill even small increases, well below 90 let alone maximal, either have or are in some way linked to significant negative effects and all sorts of craziness with HR and my wider body throughout PEM.

All this is to say, I can see why measures of HR, maximal effort, etc are not linked to whatever is going on. I can see the simplistic attraction of these exercise tests, especially from the perspective of a well person or someone not familiar with ME/ FS. But something which excludes anyone beyond the most mildly affected and is based on what seems to be a misunderstanding of the condition seems odd to pursue.

It was embraced and promoted particularly (in the UK) as it seemed to deal a death blow to CBT/GET and from from lumping thought. Splitting can allow that it may be very very important in some and not in others. It remains fair imo to point out that 2 day CPET is off in a cohort of ME diagnosed and that this is indeed contrary to what is expected and found n deconditioning. and is not found in other diagnoses e.g. sarcoid where sth phenotypically similar to PEM is frequent. Any UK broadsheet article on ME will have several comments below insinuating that ME fatigue and indeed LC are deconditioning. It is still relevant imo to point out that according to CPET for some pwME at least, the deconditioning hypothesis is not supported. Of course relating CPET to symptoms is another matter and I recall the "no CPET worsening no ME" proclamations with regret.

 

[richie]

Sorry but I find it difficult to read whole threads. Was there not an issue with aerobic deconditioning such that Keller did not factor it in early. was criticised but later did and still got the 2 day CPET worsening?

 

[Utsikt]

My max My HR was above 190 in my late twenties, and I frequently got up to >190 within minutes when exercising as instructed after I got ME/CFS. It was intense short intervals of full body cardio.

I have no idea what my max is now. I’ve had >160 when lying down on a couple of occasions.

 

[EndME]

The same criticism could be made of this study - an average peak heart rate of 155 bpm is far from maximal effort for people with a mean age of 38.

Unfit people actually tend to have higher peak heart rate than trained athletes. I was tested in my mid 30s and my heart rate peaked over 200bpm on the first day and over 190bpm on the second day.

That seems very low indeed!

 

[Chandelier]

Todd Davenport has just published a blog which I interpret as being, at least in part, a response to this paper. Curious what people make of his arguments.

New blog post by Todd Davenport:

Deciding Whether to Use the Ramp or Take the Steps

How Choices About the Cardiopulmonary Exercise Test Protocol Can Show Up in the Analysis

likeannopeningbandforthesun.substack.com

Deciding Whether to Use the Ramp or Take the Steps​

How Choices About the Cardiopulmonary Exercise Test Protocol Can Show Up in the Analysis​

TODD DAVENPORT
JUL 03, 2026