Based on ideas from
www.modelgolf.com and
Dr. Mann's excellent book
Swing Like a Pro

Shift-Turn-Shift-Turn

Proper timing of the Shift-Turn-Shift-Turn sequence is all there is to it in unleashing enormous power in the golf swing! The key lies in a two-directional transition motion that occurs near the top of the swing. The simultaneous completion of the backswing turn coupled with the beginning of the downswing shift creates the potential power. A tremendous whip-like energy gets stored in the big muscles that then gets transmitted to and released by the smaller muscles, which causes the club to ka-fling into impact.

Backswing

Downswing