From a little something I wrote based on an article my chiropractor gave me a about spinal injury due to rotation.
"The Golfing Machine by Homer Kelley teaches that there are four sources of power in the golf swing, known as Power Accumulators- or Power Sources- none of which are based on torso rotation.
The turning of the body, "pivot", should be a reaction to where the hands need to go. This is referred to as a "hand controlled pivot" in The Golfing Machine. Many teachers believe that the rotation of the body controls the hands. This is fine if you want to hit less than your maximum distance potential and create room for injury.
The geometry and physics of the golf swing, studied by all Authorized Instructors of The Golfing Machine, dictates that the hands always have a destination. Give your hands an assignment, where to go and what to do, then have them complete that assignment. The body should play a supporting role, and not vice-versa."
__________________ Hitting the Ball is the easiest part of the game-hitting it effectively is the most difficult. Why trust instinct when there is a science."1-G.