A reverse spine angle is defined as any excessive upper body backward bend away from the ball or any lateral bend towards the target during the backswing. This swing fault makes it very difficult to start the downswing in proper sequence, due to the lower body being placed in a position that usually limits its ability to initiate the downswing. This swing fault is also one of the prime causes of lower back pain. When the lower body can not start the downswing and has a limited ability to initiate the movement, the upper body tends to dominate the swing which will eventually create path problems and limited power generation. This swing fault puts excessive tension on the lower back due to a forced inhibition of the abdominal musculature during the backswing.
In order to maintain your spine angle during the backswing several physical characteristics must be developed. First and foremost, the ability to separate your upper body from your lower body allows your shoulders to rotate around your spine without going into backward bend or excessive target side lateral bend. Limited trunk to pelvis separation is usually caused by reduced spinal mobility and shortened lat flexibility. Secondly, trail hip internal rotation is necessary for full rotation into this hip without any lateral movement during the backswing. If the body is unable to rotate around the trail hip due to joint or muscular restrictions then a lateral sway may occur. Any lateral sway during the backswing will force the spine to tilt into backward bend and create a reverse spine angle. Finally, the ability to stabilize your spine angle during the backswing is directly proportional to the strength and stability of your core musculature. These muscles help keep your trunk forward flexed throughout your golf swing.