Do you know what has now become (not the original intent of the OP) so hilarious about this post? And, I set my original performance practice video as a predicate.
That means: picture in your mind how a pianist (including the most famous) of the 19th century looked and sounded at the piano during an average performance.
Accordingly, have you not ever seen a photograph or a daguerreotype of Franz Liszt, Clara Schumann, and Chopin sitting at the piano?
They are not positioned on a modern piano bench, not one single one of them. Hey, then how did they play this very technically challenging and exquisitely beautiful music sitting on a glorified "CHAIR?"
The fact of the matter is that THEY DID!
Additionally, today there is wonderful beautifully gifted man/pianist by the name of Frederic Chiu (
www.fredericchiu.com), a stellar student of Abbey Simon, who sits in a chair. Further, he has had many special versions crafted for him over the years.
Please visit his website and learn what you can about the sitting body mechanics about playing the piano.