extending your arms

[shoshin]

How far should you extend your arms from your torso? Like how far back should you sit from the piano? Maybe what ranges of angles should your arms and forearms make?

From what I've read alot is personal preference and whether you are playing black or white keys.   I was just wondering if there is some kind of posture rule or guidelines for how far your arms extend out.

Thanks.

[xvimbi]

The "rules" I apply to myself is to sit far enough back so that my elbows can move fairly easily in front of my torso without bumping into my sides, and not so far back that I would have to engage a lot of back muscles to keep my body stabilized.