Let’s talk about flexion and extension of the spine. We’re going to jump during the golf swing to get some vertical force to help you hit the ball farther. In order to do this, you need to flex and extend. If we were just thinking about jumping, we would start flexed and then we would go into extension to jump up and down. This same thing happens during the golf swing.
When you get to address your spine is flexed and during the backswing, you lose that flexion and go into extension. You need to regain that flexion in order to build extend through impact so as you start coming down you go back into flexion when the club is parallel to the ground just before impact. From here, you get to extend up into the finish and explode off the ground. At the end of the golf swing, your spine should be fully extended. Using the ground to propel you up will give you a lot more power in your golf swing.