Originally Posted by
JakeAcci
I don't recall that qualification. A lot of medical advice gets passed around on non-medical boards by non-medical people so I don't want to do a disservice by continuing that tradition.
I'll just relay what my (now distant) memory tells me about the warning: if you play in a brace without training yourself to not move that joint, you are exerting effort and using that muscle often up against the 'wall' of the brace which can cause problems, kind of like a straightjacket for your hand. Since I'm not a doctor I can't give a much better answer than that, but it might be something worth researching if this is a common practice for you.
I'll also say that as a person who has spent a ridiculous amount of time analyzing his playing position and that of others, it is very much possible to train yourself to never or rarely bend at the wrist joint, even during stretched chord voicings. Playing with a straight wrist is something I take very seriously.