Dutch long covid study with muscle biopsies after exercise challenge

Professor van Vugt: “Just by looking at the muscle biopsies, you see that the firmness of the muscle is different. The firmness of the muscle has to do with the connective tissue, and there are now many theories about that.”

https://twitter.com/user/status/1532341518668861440


My understanding is that the samples have been collected but there isn't enough funding to analyze them in depth, but maybe that is information is already outdated.

 

This is interesting. I assume this refers to microscopic firmness, but on a macroscopic level my muscles have completely changed since I've had ME. My muscles are lumpy and toughened just under the skin, and this lumpiness can be associated with extreme tenderness. It feels like there is significant facial involvement. @Jonathan Edwards Have you ever encountered this in your time in rhematology, or have any feeling about what might be going on?

 

To be honest I don't know what he means. Firmness involves compression or manipulation so is a macroscopic phenomenon. Muscle biopsies are pretty squishy normally and at least in the old days were carefully laid out on a card and then processed for sectioning and not prodded about. I don't think connective tissue has much to do with the physical properties except maybe in fibrotic muscle. It is not even clear as to whether he means firmer or less firm.

I have not heard of change in texture to muscle in ME. Fascia is outside muscle but there are finer connective tissue layers within the muscle (perimysium). If there was anything significant to find it would have been found on previous muscle biopsy studies I think. I am not aware of any texture changes clinically except in overt myositis - or chronic changes particularly in dermatomyositis - where biopsy findings are gross. Nothing is said here about routine histological findings.

 

Thanks. Yep, I have done a bit of interent searching over the years and myositis is the one thing that always comes up. But I don't think I have any overt signs.

 

Again I know nothing but if your daily activity wasn't typical [activity of people with ME/CFS is much lower (EDIT & presumably for people with long covid?)] then perhaps that would explain the (EDIT - difference)?

 

Yes, I'd like to see some evidence of this phenomena before accepting the claim...

 

... and a lot more details.

 

Looks like the Danes have published first.