When you swing a golf club your head appears to stay fairly still. But it is not because your are trying to hold it still. It stays fairly centered because you body is constantly pushing away from the motion of the club. So as the club moves back my body is starting to move forward. As the club swings around me on the down swing my body is moving away from the motion of the club. As I swing into the finish I am again pushing away from the motion of the club. Most great players heads actually appear to move back as the club goes through the ball. That is because they are pushing back away from the forward momentum of the club. That also creates a tremendous amount of acceleration.