I found this interesting:
The pitcher also performs lateral trunk lean in the direction of the pitching arm during release- this movement increases the moment arm for both spinal rotation and rotation around the left hip. The axis for spinal rotation passes through the spine, so that slight abduction of the arm about the shoulder joint will increase this distance. The axis for rotation about the left hip passes through the left thigh, and leaning sideways away from this axis will increase the moment arm for rotation about this axis.
The pitcher also performs lateral trunk lean in the direction of the pitching arm during release- this movement increases the moment arm for both spinal rotation and rotation around the left hip. The axis for spinal rotation passes through the spine, so that slight abduction of the arm about the shoulder joint will increase this distance. The axis for rotation about the left hip passes through the left thigh, and leaning sideways away from this axis will increase the moment arm for rotation about this axis.