Exercise during artificial gravity preserves cardiorespiratory fitness but not OI following 60 days of head-down bed rest (BRACE), 2025, Hedge et al

[Mij]

Abstract​

Exercise is a critical countermeasure to prevent cardiovascular deconditioning during spaceflight; however, exercise does not protect astronauts from post-flight orthostatic intolerance. Artificial gravity (AG) by short-arm centrifugation can attenuate reductions in orthostatic tolerance following prolonged head-down bed rest (HDBR), but AG does not protect cardiorespiratory fitness.

The European Space Agency hypothesized that exercise and AG countermeasures could be applied simultaneously to protect both cardiorespiratory fitness and orthostatic tolerance following prolonged HDBR.

Twenty-four healthy men (age: 29±6 yr, peak oxygen uptake: 47.5±6.0 mL·min-1·kg-1) completed 60 days of HDBR and were randomized into either sedentary control (n=8), exercise (n=8), or exercise + AG (n=8) groups. Exercise participants performed 30 min of high-intensity interval cycling on 49 of 60 days during HDBR. The exercise + AG group performed the same 30-min exercise program while spinning supine in a short-arm centrifuge to generate a head-to-foot acceleration. Peak oxygen uptake (HDBR×group: p<0.001) was reduced in the control group following HDBR (Δ=−24±5 %) but was protected by the exercise (Δ=0±6 %) and exercise + AG (Δ=4±6 %) countermeasures.

Time to pre-syncope was reduced in all groups (control: Δ=−9.0±3.4 min, exercise: Δ=−12.4±5.2 min, exercise + AG: Δ=−4.5±8.8 min) following HDBR (main effect: p<0.001). Activation of the muscle pump during exercise likely minimized the redistribution of blood volume into the legs and consequently, the simulated orthostatic stress experienced during centrifugation, preventing benefits of exercise + AG on orthostatic tolerance following HDBR. Therefore, AG by short-arm centrifugation should be implemented at rest or post-exercise to protect orthostatic tolerance.
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[rvallee]

So OI would be independent of de/conditioning, and obviously exercise would not fix OI. Which makes sense, they don't seem to overlap in any way unless someone badly wants them to and would accept the mere ability to conceive of it as plenty of evidence for it.

I noticed in a recent thread on a medical sub-reddit, I think it was the article about the UK girl and Lyme disease, and one of the comments quoted in the thread was so damn odd, basically something like because of how people with chronic illness are warned about PEM and the harm of exertion, kids these days are foregoing exercise entirely, and giving themselves POTS as a result. Even though as we know much of this is happening within entirely insulated social bubbles that everyone ignores entirely.

Which is of course completely ridiculous and happening exactly as much as kids were actually eating Tide pods as a challenge (or listening to rock albums backwards to commune with Satan, or whatever). People don't develop POTS or OI from being sedentary, we know this because a lot of people are sedentary and, not surprise, no POTS or OI.

But, somehow, some doctor in the UK, a resident I think, believes that, and is unlikely to be the only one. I doubt this study would burst that belief. Beliefs are weird. I don't understand beliefs, or why people have them, they make no sense to me. But even in a sea of bizarre beliefs, it struck me as especially odd. And, of course, completely wrong.

It would be especially important if it were not ignore because a lot of what's been happening with exercise rehabilitation, especially in Long Covid, is the firm conviction that improving respiratory fitness is the key to everything. A silly belief, debunked by having tried and failed for years, but hardly anyone seems to care. Beliefs just go on anyway.

 

[Utsikt]

So OI would be independent of de/conditioning, and obviously exercise would not fix OI.

OI seems to be dependent on a prolonged lack of challenge to the vascular system’s ability to compensate for gravity to get blood to the brain.

Mostly based on exercise in artificial gravity not working because the leg muscles do the job for the rest of the system.

Which just means that lying down a lot might make OI in ME/CFS worse, but due to PEM for OI makes it very difficult to reverse it without an improvement in the underlying ME/CFS.

 

[MeSci]

"Exercise during artificial gravity preserves cardiorespiratory fitness but not OI"

So it doesn't preserve orthostatic intolerance???