Todd Davenport Profile picture
Feb 21, 2024 11 tweets 2 min read Read on X
The conclusion of "alteration of effort preference" driving PEM from an underpowered study that blatantly misuses CPET in the face of all relevant research and clinical guidance for ME/CFS is what we get after years of developing the protocol and waiting for these results?
The sample size makes this study a glorified case series. In a heterogeneous condition like ME/CFS, there is no way 17 participants out of 217 screened is representative. But get this: not all the participants got all the endpoint measures. How can the authors infer causation?
For sure the CPET results are underpowered but there are some clear differences between groups. The authors interpret these differences as deconditioning, which is easy to do on the basis of a single CPET. That's why you need the second one completed in the post-exertional state.
One revealing thing from CPET was the fact the authors included obviously trained individuals in their analysis. Half of them performed at or above their age-predicted maximum heart rate. If you want to conclude PEM is deconditioning and altered effort preference, at least...
...make this comparison with sedentary people who are likely to be deconditioned instead of relatively fit individuals.
PEM is tricky because simply trying to measure it can induce it. The authors didn't grasp this important concept. The effort preference task is a lengthy complex choice reaction time task. This just sounds like the perfect way to induce cognitive PEM during a measurement.
So, there will be a lot more said about this study in the weeks and months to come, and most of it will be about how this study wasn't worth the resources, time, and waiting. For now I'll just contribute that Nature editorial staff were asleep at the wheel, ...
... there were plenty of people who had to do with this work who had reason to know better than what they put out both from basic scientific and content area perspectives, and this work is so poorly interpreted and so poorly reported that it should be retracted immediately.
This article reinforces every negative stereotype about PEM simply being a choice. It's so inconsistent with the findings of their own -omics analysis, to let alone the extant literature. And in light of that inconsistency, it's inhumane. People with ME deserve better than this.
There may be some useful details of this work stuck between the couch cushions, but they won't make the global headlines. What will make those headlines are people with ME are either lazy or crazy. Again.

What an utter and total waste of resources and good faith. I just can't.

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More from @sunsopeningband

Sep 7
If exercise makes symptoms worse…you know that exercise makes symptoms worse.

You do not know if it’s PEM from that observation alone.
For example, I work with people who have low back pain. Sometimes the treatments I provide overload things enough they feel a little worse temporarily. There’s a school of thought that says exercising into a little pain might even be helpful because it gets even better over time.
Getting worse after activity is PESE. It makes no assumption about the underlying capacity of tissues and systems to respond, just things got worse. PEM is a worsening in function in response to activity over time, suggesting lost tissues’ and systems’ ability to respond to load.
Read 4 tweets
Sep 6
Today’s unpopular opinion is evidence based practice isn’t just following a cookbook established by scientific research or the lack of it but it also involves a meaningful synthesis of lived experience and clinical judgement as co-equal sources of evidence. Three legs of a stool.
This means that, to practice in an evidence-based manner, we are *obligated* to meaningfully elicit the patient’s perspectives on what’s happening to them and why, including information they obtained from Internet searches, AI ramblings, social media, and patient support groups.
And not only are we obligated to meaningfully elicit that information, we are similarly obligated to substantively respond to and integrate those perspectives into decisions made about a plan of care. You see, there is some really good and helpful stuff floating around out there
Read 8 tweets
Sep 5
I’ve now been able to read the new iCPET paper a few times (I’m slow). As you know, I do love a CPET paper. My first thought is: good that a second group is using this methodology for replication purposes. Adds credibility to the findings if more than one group are finding them.
My second thought is: they didn’t seem to have any requirement for max tests. They mentioned respiratory quotient for their healthy controls, but not for their patients. Why is this important? The potential to compare apples with oranges: results of maximal and submaximal tests.
How do I know? The 25th percentile for RQ was below 1.15. This suggests a lot of variability around the median and potentially values below the generally accepted cut offs for achieving a maximal test. True that they observed the same spread in their healthy controls, but with a
Read 5 tweets
Aug 16
We still know precious little about PEM, but one thing's for certain--it represents an impaired recovery response to exertion. How do we know this? We had data from systems to molecules, replicated across myalgic encephalomyelitis cohorts originating regardless of patho-etiology.
Who cares? Because a foundational aspect of being human is being able to count on physiological adaptations to exerting ourselves. Walk a little more so you can walk a little more. Read a little more so you can read a little more. Do some more to do more later. It's fundamental.
One way to think about this that has been described is the 'energy envelope.' (The terminology imprecision makes me a little crazy as a physio and exercise scientist, but it's popular and we'll go with it.) The energy envelope is the total amount of energy available to do things.
Read 18 tweets
Aug 16
Maybe it’s just another day ending in “y” around here but I’ll volunteer we can never do enough to educate health care practitioners about PEM—the thing that breaks all the rules. We simply can never have enough caution and clarity surrounding PEM, particularly how to do no harm.
In trying to understand this confusing phenomenon, I’ve spent more times wrong than right. After all, as a researcher all your best ideas are still just hypotheses and as a clinician the best you’ll ever do is still considered practicing. The greater pursuit isn’t to be right…
it’s to *get it right.* Sometimes that critique is pointed and direct. There’s a lot of painful experiences and trauma out there. As someone studying a phenomenon I don’t live with, the best I can do is be a knowledgeable and empathetic interloper. But an interloper nevertheless.
Read 4 tweets
Jun 15
The sooner we can move away from this still-pervasive idea that PEM is a feature of multiple conditions, the better. We’re still not seeing the forest for the trees. It’s hurting our ability to subgroup patients with different kinds of triggers that share common pathophysiology.
Here’s some data from a recent study we did with patients reporting PEM/PENE. Notice the overlap between Lyme, SARS-COV-2, Gulf War Illness and other conditions. Not all people with them have PEM/PENE and meet criteria for ME, but the ones who do…have ME. journals.sagepub.com/doi/10.3233/WO…Image
(Rolled up on the “Other” are enteroviruses, which I somehow forgot to put on the demographic form. Gah. 😩)
Read 12 tweets

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