Twenty-One Days of Bed Rest Alter Motor Unit Properties and Neuromuscular Junction Transmission in Young Adults, 2025, Sarto et al

[Mij]

Abstract
Previous studies showed that properties of higher‐threshold motor units (MUs) and neuromuscular junction (NMJ) function are preserved during short‐term disuse. This study aimed to test how a longer disuse period affects MU properties, NMJ transmission, and NMJ morphology remodeling.

Nine young healthy males (age: 18‐29 years) underwent 21 days of horizontal bed rest. Pre‐ (BR0) and post‐bed rest (BR21), quadriceps maximal voluntary contraction (MVC), and size were assessed. We combined intramuscular electromyography (iEMG) and high‐density surface electromyography (HDsEMG) recordings on the vastus lateralis to assess MU properties at 25% and 50% of MVC.

Muscle biopsies and blood samples were also collected. Quadriceps MVC and size decreased at BR21. We found alterations in MU properties at both contraction intensities, including reduced discharge rate, MU potential area changes, and increased complexity. NMJ transmission was found to be reduced at BR21 at 25% MVC.

This functional NMJ impairment was biochemically corroborated by an increase in serum C‐terminal agrin fragment concentration, a biomarker of NMJ instability. In addition, a direct assessment of NMJ morphology revealed the presence of some denervated NMJs exclusively at BR21.

In conclusion, 21‐day bed rest altered MU properties across different contraction intensities and impaired NMJ transmission with initial signs of remodeling/denervation. Disuse duration appears to be a critical factor, as previous shorter studies failed to detect some of these changes.

We believe these findings are clinically relevant for disuse after trauma, surgery, or illness, and may support the development of effective countermeasures.
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[bobbler]

None of this theory makes sense surely to anyone who lived and was old enough to observe other people 20-30 years ago before all this brainwashing started

as an athlete on lots of sports teams for many years it’s the norm that almost everyone will have a bout of something that puts them in bed for weeks then returns to school and takes maybe a few more weeks to get back up to ‘full fitness’ in sports but is basically the same. Whether it’s flu tinsilitis or mumps or whatever was going around

and eg sports like athletics measure this exactly because you are taking the times on your training runs and competitions - and those triangulate precisely with other sports. It’s nonsense you get anything other than temporary partly because you are still ill and a bit out of the game ‘loss’ from rest. The opposite was very much true from going back too early. So the rehab stuff blurbed as for all smells.

And they must really if they are honest see it in military stuff as people must get ill or injured enough - if they cared to measure it at 2months back and recovered.

certainly sports proper professional level ones know all this. They aren’t saying the sprinter or marathon runner should scrape back when still ill a week early because it’s the bed rest that will write off the upcoming season, but not recovering properly from their glandular fever

It just doesn’t fit with truth of the day to day every day around us, until they coerced and gaslighted people to lie and self deceive then started using subjective measures so people felt they had to do the right thing and tell themselves that was the best decision - we all did it. But most who care can also see it in people with the strain in their smile or weary at end of day in their eyes stuff.

I don’t get what they think they’ve proven here other than apparently if you take time off physical training you need a bit of time to get back to where you were

but it doesn’t go away. The fact that in the gym I looked fitter muscle wise and was than people who’d been lazy non sporties when young then got into whatever late thirties having been an athlete when young then had ME for the prior decades was obvious in what I could do, it was the open of course and the long term impact of it that was different. So no that muscle doesn’t go away, not even after decades , until you push people to overdo and me ravages when combined with that.