Hip rotation in a golf swing is one of the most important parts of developing an efficient golf swing. In a study presented by the American College of Sports Medicine, researchers looked at the difference between hip strength and level of golf ability and the difference between hip strength and self-reported driving distance. Researchers studied the strength of the hip muscles that move the legs toward and away from the center of the body (hip adduction and abduction strength, respectively).
The study showed hip abduction strength was significantly higher in better golfers. In addition, all the hip movements tended to be stronger in the best golfers who had the lowest handicaps and longest driving distances.
The hip abductor muscles are a group of four muscles located in the buttocks region on both sides of the body. The abductors' main function is to abduct, or separate, your legs away from the midline of the body. This occurs in the golf swing when you shift your weight on the backswing and downswing.
If your hips are tight and weak, the tendency is to slide the hips to the side on the backswing instead of turning them, which causes the dreaded reverse upper body tilt (left photo).
This is a very weak position in the golf swing and will cause numerous faults in your swing. Ideally, you want to rotate your hips on the backswing in order to load your weight correctly. Think of winding your upper body over your lower body, so that your left shoulder (if you are right-handed) ends up over your right knee. You will now have your upper body stacked correctly over your rotated hip (right photo).