Originally Posted by ndtennisfan
Is it because of the flick of the wrist necessary to generate the spiral? Same principal holds true in golf ... if you want to generate massive clubhead speed, it's all about waiting until the last moment to 'pull the trigger' and break your wrist to bring the clubhead through. Watching Serena's serve in slo-mo, the wrist snap is ridiculous.
If you watch instruction on how to throw a football you will see forearm pronation. But they don't call it that. The follow through after pronation (wrist snap) is to the left hip. For a righty. The motion almost mimics exactly the flat serve with forearm pronation on the right of the body and the follow through to the left of the body. The snap. Whippy arm. It's all there.