Interestingly, I also studied piano for many years (from age of 5 until 18 I guess). I agree, wrist flexion is important, and I definitely do flex my wrists (sometimes in a seemingly exaggerated manner) when playing piano, however, for typing, I can comfortably type anything I want, including special characters, without flexing my wrists. Not sure if this is a sign of a well designed layout or RSI waiting to happen

Perhaps weighted keys make the difference?..

Yes, that's a very good point. The keys I'm using are Cherry MX Clears which have an actuation force of 55cN. From my own experience, it would require a lot more force to depress a piano key. So yeah, maybe wrist flexion is pretty much required when playing piano to avoid muscular fatigue in the fingers.

>it would require a lot more force to depress a piano key

55cN is a little on the high side for force needed to depress a piano key ("touchweight"). But the piano is velocity sensitive, and pressing with the minimum force won't get you any sound. Playing loud notes takes substantially more force.

It always amazes me how much wisdom is common knowledge in other pursuits or even cultures that does not show up when trying to search for solutions to problems in other endeavors. I think its one of those under researched fields of AI to try to link areas of knowledge where someone searching for RSI would see sources from piano training showing the need to flex the wrists.

You can also ask an ergonomic specialist, they do refer to piano posture at least.

Yeah, experts tend to explore related fields (I guess that's why they are experts), but I do wonder when actual, relevant one-off searching will actually work.