Body positioning is a loaded topic and there are multiple layers to it, and it’s not cut and dry.
Our muscles and joints in our body, they have specific jobs and specific positions that they like to go into. They have very specific ways that they want to work.
Our instruments require them to go into positions that they are not exactly happy in. We have to move in and we also have to move out of these positions.
I see musicians move into positions that are not ergonomically the best for that body part, and they stay in it. The key is to not stay in those positions longer than you need to.
Everybody is different. My fingers may be longer than yours, or shorter. So if you’re looking for key positioning, then it’s very different. Your arm length may be different from somebody else’s. All that plays a role.
People have differences in their upper body length and lower body length, and that makes a difference for guitarists or pianists for example. Not everybody is the same. Customization is important.
Stop and think about what your body type is and how your body type fits your instrument.
The energy in which we approach our instrument is also important.