What happens to muscles in fibromyalgia syndrome, 2019,

Paywall, https://link.springer.com/article/10.1007/s11845-019-02138-w
Scihub, https://sci-hub.se/10.1007/s11845-019-02138-w

 

This seems weak at first glance because of how crude muscle mass is but:

However given how long it typically takes to get diagnosed, symptoms will have usually already have had an impact on physical activity, though we are talking about a reduction of activity, not months of complete bed rest. There's a big issue as with ME about time of diagnosis not necessarily being nearly as significant as time of symptom appearance. It's not clear in discussion how thorough they were to establish a rough time for when symptoms became significant enough to affect functionality vs. time of diagnosis.

This is discussed here, but it's hard to be precise when so little is known about disease progression:

Would look at that: common sense, measuring muscle groups not typically involved in regular physical activity and bypass the issue of deconditioning. More of that, please.

What's with the deltoid?

It would pretty much take complete inactivity to avoid using deltoid muscles altogether so that's interesting. It would be interesting to be able to measure muscle density, to determine whether the mass has decreased or has simply become more densely packed, less flexible. After all muscle power is all about contracting fibers so if they are stiffer it could have the same outcome.

Didn't look like much but altogether interesting.

 

Just for the record, from research in the 1990s, no pathology found in the muscle tissue via microscopic analysis of fibro patients.

 

to add: https://www.ncbi.nlm.nih.gov/pubmed/2644673

I hope this link works, has 1989 research listings on pubmed