Club across chest, turn without moving the head
A rotation drill the coach uses: hold a club across the chest with the grip pointed out, keep the hips square and the sternum still, and turn without the head moving until the shoulder points at the line. He describes the turn loading pressure into the instep, not from moving the lower body but from the upper body turning on top of the lower body.
Channel: PorzakGolf
Watch official source at 3:58