Essentially the role of the body during the swing is to start in a static position while flexed forward (flexion). Extend during the backswing and extend again to finish the swing. If you’re not doing this, you’re losing a great deal of power.

Think of jumping up off the ground from a static position. To do this you need to push down to be able to spring back up and leave the ground. Think of a high jumper or long jumper or discus thrower.

German 2012 Olympic Champion Robert Harting

It’s this action during the golf swing that creates a tremendous speed and a catapulting effect with the arms and club during the downswing.