Twitter thread by Todd Davenport, commenting on "the jury is still out":
"✌The jury is still out✌ seems like a deeply unserious response to a deeply serious issue when there’s more than enough evidence already for a jury to have decided and gone home to rest easy with their choice.
It’s all here. No wonder the good prof still has me blocked."
"Graded exercise has been studied for years in POTS, and the people who treat it with exercise rely on a largely flimsy literature to suggesting efficacy, including in this case, direct evidence from *checks reference section again* an unpublished abstract for people with PASC."
"Yet, as the authors point out, “clinical observations” and results of patient surveys suggest worsening in symptoms and functional status is common, maybe even expected, in response to prescribing aerobic exercise in people with POTS. And they don’t always get better over time."
"Don’t believe me? All good. Look at dropout rates in the few existing studies of exercise for POTS. I bet they tell an interesting albeit indirect story by themselves. Patients always seem to know something we clinicians and researchers don’t. Survivorship bias is a helluva drug."
"Now, about PEM. I venture every person living with PEM has a form of dysautonomia, either from chronotropic incompetence or orthostatic intolerance or both. In a subset of people with PEM, the orthostatic intolerance by itself is severe enough to meet clinical criteria for POTS."
"We know this from modalities like tilt tables and cardiopulmonary exercise testing. There’s enough of an evidence base to have systematic reviews on the effects of acute exercise and position changes on PEM, which are worsened in a graded manner based on functional disablement."
"We know the effects are prolonged, and with exercise, occur at submaximal levels of exertion that aren’t faked and different at submaximal levels of exertion in a way that’s different than people who are out of shape. Levels of exertion *we use to prescribe aerobic exercise.* "
"We know PEM isn’t deconditioning because we have compared the post exertional state in people with PEM

who we have shown to very likely have some type of dysautonomia) directly with people who don’t exercise and so therefore who are out of shape.
Importantly very different."
"If the acute response to aerobic exercise is abnormal, how would we expect the body to just magically begin to respond if we overload it? Simple. Based on the best available evidence we don’t. By extension maybe that’s why many people with POTS suggest exercise is unhelpful."
"In an abundance of fairness, we haven’t looked into every form of movement and exercise prescription in POTS and there is a subgroup of patients who seem to feel better with exercise. This is where we “circle back” (ugh so corporate ) to the precautionary principle: do no harm."
"If you know there are people with some kind of thing that’s worsened with exercise, and that number is potentially a lot, and that you can apply some easy clinical reasoning to avoid harms—why not just do that? Why not stop at a full throated endorsement of avoiding maleficence?"
"Well, I’ll tell you. PEM is the unreconciled “original sin” of POTS management. It was prior to PASC, and it continues to be now.
So while the “jury” has had plenty of evidence to decide, and they communicate their decision every day with their preferences and actions…"
"…they’re just waiting for us clinicians and researchers to catch up.
Because, you see, the “jury” isn’t us clinicians and researchers.
It’s the people we purport to serve."
"Anyway. Publish it in a Nature vertical or put it up on Twitter, it’s all the same to me."
"Nature won’t let you use emojis, so there’s that.

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