They say you have to play the piano without any static muscle tension. At the same time, to reach the freedom of movement your elbows should be a little bit in front of you. I have a sitting posture with by elbows and forearms looking smooth like this:
But in this position, the tension on the front delt of the shoulder is already present, since there's a small angle between the elbow and the body, although it is minumum and hard to notice. However, once I reach the black keys, which are sligthy far away, the angle between the elbow and the body increases, which creates noticeble tension in my front delts - that causes me to lean forward sometimes.
Is that normal, or am I sitting incorrectly?