It's the only way to create the speed your swing needs.
"Swinging the club faster only happens when you swing your arms faster. The trick is doing it at the right moment.
Once you've leaned into the shot like in No. 3, go after the ball as hard as you can with your arms and hands. This has been my No. 1 swing key for many years once I perfected it, I started blowing my irons and woods past players twice my size. Just make sure you don't fire your arms before leaning toward the target or you'll risk swinging off plane."