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

[richie]

I did a VO2 max test recently, and to my suprise my VO2/kg was 'excellent', and my heart rate was 'normal'. So, I was congratulated for being very 'fit'.

It is very confusing to me, because I feel far from 'fit'. When I go for a walk and start too fast, I get out of breath and feel unwell (faint, and I need to stop until I have enough oxygen again to continue walking). When I cycle uphill, the same story applies. I can walk and cycle if I go slowly, but start to feel unwell if I have to 'push' myself.

How is this possible given the good VO2 max results? The healthcare provider seemed at a loss...

Any ideas?

Maybe cytokines

 

[richie]

I wonder how that Dutch work on muscles in long covid fits in and also what was Workwell finding? Subgroups? PEM as heterogenous phenomenon? My old GP used to say "The latest thinking is" He was of course routinely disproved which was exactly his point....

 

[ME/CFS Science Blog]

Waiting to see the paper before I make any judgements as two of the authors (Natelson and Mancini) were co-authors on this CPET paper that used Fukuda to identify ME participants.

Older 2-day CPET studies such as the one by Davenport also used the Fukuda criteria so that alone likely wouldn't explain the results.

what level of severity of ME patients,

Severe ME/CFS patients can't do these test so highly likely that these were mild-moderate patients just like in previous 2-day CPET studies.

what did they use for controls

The idea was that only ME/CFS patients are unique in failing to replicate their CPET results, in contrast to healthy or deconditioned or patients with other medical conditions such as MS, lung- or heart disease. So not sure how the selection of controls would explain these results.

how did they determine sufficient effort,

If there was a methodological error that caused the lack of difference and contrasts with previous studies, think it would be something like this (patients not going deep enough on the test), or something like a high drop-out rate.

Also note that even if there is a true effect, if you do multiple underpowered studies to test it, some will have non-significant results so this isn't necessarily a big problem. Would be interesting to see what direction the effect was, regardless of the evaluation of statistical significance.

 

[Medfeb]

@ME/CFS Science Blog - My point was just that there can be any number of things that could explain differential results. I'm waiting to see the paper.

 

[duncan]

Differences in VO2Peak or VO2 at VT has not replicated in previous studies so I don't know why they're wasting their time claiming they found no results when they didn't bother to measure the one thing that was different across previous studies.

Natelson?