The Flexor Digitorium muscle system is very powerful and we use it continuously for most of our finger movements.However these muscles are not suitable for a good piano finger technique, because :1. the muscles are located largely outside the hand, too far away from the required delicate finger action.2. they cause a degree of stiffening of the wrist.3. the key stroke becomes a pushing action rather than a freely rebounding gravity stroke.This results in a lack of tone quality, resonance, clarity and fluency .4.excessive use of these muscles in piano playing can easily lead to repetitive strain injury (rsi) and inflammation of the wrist.... Instead:When used simultaneously the Palmar and Dorsal Interossei flex the knuckle joint forward (or, when the hand is in a horizontal position, downward).Most importantly these muscles are located entirely within the hand palm, and therefore can flex the knuckle joint (and achieve a proper finger action) without stiffening the wrist. For a good finger action in piano playing we must therefore use the Interossei muscles and flex the fingers from the knuckle joints. This leaves the wrists relaxed and flexible.There is however a problem.In every day finger movement the Interossei play only a secondary and supportive role in flexing the knuckles.... Therefore, you must upgrade the Interossei from weak supporting muscles to become the Prime movers and learn to trust and rely on them in that dominant function.
Information about what muscles do what is one thing but it doesn't tell you what to actually do.
My question would be how do you know whether those claims are true? Can you show that someone trained in the "French technique" uses their interossei more than the larger flexor digitorum muscles?
I personally don't think considering piano technique in terms of your physical body in isolation to actual music is useful at all. You simply need musical context to explain what you do, segregating it from context simply leaves you with a muddled mess.
As soon as I encounter a new piece of information regarding technique, it is never independent of context for me, because I always create the context around it, derived from the nature of the movement. For example, I will see how the movement affects scale playing and how the piano responds, try out snippets of various pieces, etudes, etc. depending upon the movement. If all else falls, I will create my own improvisations and exercises around the idea and see how it can be used to make music. As you know, I'm a technical experimenter
This is partly why I asked the question, to see if anyone has any real rebuttal to this. I used to think playing with the fingers = tension, but as someone demonstrated to me and I subsequently tried out, that doesn't appear to be the case when done correctly (without excess tension anywhere else in the playing apparatus). It's an immediate pushing motion followed by a rest. I have only heard anecdotal experience. I don't dismiss anecdotal experience by really good players though, because from what I've seen the science of the movements behind piano playing is still in its infancy, so there's a lot that hasn't been studied.
Like how would you play without playing with the fingers?
If you are told never to flatten your fingers and believe in lots of what is said about how your muscles are supposed to feel like you might miss out on important ways in which you can connect with the piano.