Importance of the Back Knee Flex

During the setup in a golf swing the legs are flexed at address, and the back leg must remain flexed throughout the back swing movement. his is a must for a correct body turn.

By maintaining a flexed back leg the head is held at a constant height from the ground during the back swing. It does not bob up and down.

Promotes Better Body Turn

The flexed back leg promotes a full and correct body turn. By remaining flexed and active the hip and side can be fully cleared to the rear. During the turn of the golf swing the rear hip goes back, but it must not be allowed to rise up. If the back leg straightens during the back swing a full hip and shoulder turn will be virtually impossible. Further, the head will tip over in the direction of the target and the "shape" of the body turn is destroyed, as is the plane of the back swing.

Role of the Knees

Powerful driving begins from the ground up. Top golfers generate power by making a huge shoulder coil above a braced lower body. If you have weak, loose or overactive knee action, you'll have slack in your coil -- a major power leak.

Resistance and counter forces Power comes from "the resistance of the hips to the turn of the shoulders in the back swing".