Pelvic Movement

Pelvic movement in the golf swing is a key indicator of how the golf club will move throughout the swing.  Just by knowing how the pelvis is positioned at impact through 3D motion capture we can glean a lot about the path, angle of attack, and dynamic loft of the club being swung.  Even the most subtle differences in pelvic movement can mean significant changes in clubhead delivery.  
One common swing flaw at impact is too much pelvic side bend (left hip high for right-handed golfers).  This indicates a slide where the pelvis moves towards the target for too long and does not rotate properly.  As a result, the spine will also be tilted away from the target too much and the club will fall back and be delivered too much from the inside.  The usual shots that show up are blocks, hooks, and occasional fat shots.  The answer for this is to work on rotating the pelvis sooner in the downswing to keep the club in front of you and on path.
Another swing flaw which is even more common is early extension.  The exact definition of this is to extend the body from the hips or to straighten up from a forward bend position.  There are different versions of early extension, but let’s look at one common version.  Many golfers will start the downswing with some pelvic rotation and then quickly straighten up or early extend.  This means that there is a lack of side bend through impact.  This almost always means that the club will be delivered from the outside as the right shoulder will not come in low enough to deliver the club on path.  The answer for this is to learn how to start the downswing with some downward pressure into the ground and then rotate in a way where the lead hip works up and around.  As you can see in the photo above Tiger has moved into his left side and is ready to start pushing up through the left foot to rotate the pelvis resulting in a strong position at impact.
Understand that the pelvis is the hub of the golf swing and therefore much attention must be given to learning how to move it through the swing properly.  If you are not sure how your pelvis moves through the swing then get evaluated so that you have a better understanding of this all important piece of the puzzle.
Practice Smart!
Photo Courtesy of Golf Digest