This is an essential skill for a gymnast.  It is a way to move the body quickly from a hang to a support position.  It is also a common stumbling block for new gymnasts, and often times, this skill takes months to learn.  To perform it properly, the gymnast must stretch the swing as far forward as possible before bringing the toes up to the bar (Pike).  Once the body begins to swing backward, a combination of shoulder, abdominal, and arm muscles are used, to force the bar downward, and allow the body to rise to a support position.