This is one of the first skills gymnasts come up against that requires strict attention to technique.  The gymnast should start in a support position, with the bar pressed down to the mid-thigh.  In a straight position, the gymnast falls forward.  The gymnast maintains pressure between the bar and the legs, and at the bottom of the circling motion, the hands are shifted, so that they are on the top of the bar (still in “overgrip.”)  Simultaneously, the body is forced into a Hollow, which accelerates the body back to a support position.  The arms should remain straight throughout, and the head should remain neutral.