Originally Posted by MoAlpha

As a hospital-based physician and fitness nerd, I don't doubt it at all. Here's a pretty good review of what happen to muscle when oldies stop moving.

https://www.ncbi.nlm.nih.gov/pmc/art...MC3276215/#R13



The study subjects in reference 13 were healthy volunteers, mean age 67, maintained on a normal diet. The full text is paywalled, but I can send it to anyone who's interested.

The OP was not on complete bed rest, but the acute phase of recovery from significant injury involves systemic inflammation and a catabolic state, where resources are diverted to healing and anabolic processes, such as amino acid deposition in muscle, is effectively halted.

Most old people are losing muscle at a slow, but measurable, rate anyway and the only way to maintain it is resistance exercise and lots and lots of dietary protein.