Once a pianist is physically and mentally exhausted, the possibility of injury through inappropriate movements becomes a major danger. Her concept of rotation is a key to understanding how to coordinate efficient motion at the piano. Single rotation involves a change of direction from right to left or vice versa. The power afforded by rotation enables the fingers to play deep into the keys, without cramping or discomfort. A preparatory swing in the opposite direction is completed by a full rotation into the key in the forward direction.
Posture is crucial - sit straight, with firm shoulders pulled back and the chest forward.
This creates a proper sense of balance at the piano. The wrist acts like a springboard, and should not be forced down in a collapsed position. Total relaxation is not the goal - neither is holding extreme body positions. Joints must not collapse, because they prohibit free motion. Tension will result, just as it can be caused by excess muscular activity.