Early extension is defined as any forward movement of the lower body towards the golf during the downswing. This swing fault causes the arms and club to get stuck behind the body during the downswing, and forces the torso to rise up and elevate through the impact zone. This swing fault usually causes the block mishit and a hook. Golfers with this trait usually complain of getting stuck or trapped, this is due to the fact that the lower body has moved closer to the ball during the downswing. As a result, the body is in the way of the arms on the downswing.
In order not to early extend during the downswing several physical characteristics must be developed. First and foremost, research has shown that any limitation in performing a full deep squat or full hip bend can force a player to early extend during the downswing. Failure to perform these movements means generalized stiffness or asymmetry in the musculature and joints of the lower body. Secondly, lead hip internal rotation is necessary for allowing the lower body to fully rotate without any forward thrusts towards the golf ball. If the pelvis is unable to rotate around the lead hip due to muscular restrictions then forward and lateral movements will result. Thirdly, the ability to separate your lower body from your upper body allows the lower body to stabilize while rotating your shoulders through impact. Limited trunk to pelvis separation is usually caused by reduced spinal mobility and shortened lat flexibility. Finally, the ability to stabilize your lower body is directly proportional to abdominal strength and control of the pelvic musculature, which help control the movement of the pelvis during the downswing. These muscles help prevent the lower body from thrusting towards the golf ball during the downswing.