Ok, parametric acceleration! Interesting that in 2016 I wrote an email asking Andy Fitzell about parametric acceleration. Mr. Fitzell makes some very nice video.
I started messing around nunchucks trying to understand tennis stroke a couple of years back. Knowing how to whip nunchucks enable me to whip a tennis racket with 2 fingers. Yes, the racket can come around very quick with very little effort, if you pull it just right.
My understanding is that some form of parametric acceleration probably exist in all forms of tennis swing. If it is not used then everyone will be manipulating the tennis racket as if it is one rigid unit from the racket all the way to the shoulder. Yes, that is kind of a visual model I get when I read Vic Braden's books, keeping wrist firm, swing the racket from the shoulder. I get it, keeping everything in relatively fixed angle and you keep things simple and be more consistent. But in reality, everything flexes. Parametric acceleration is in even in waiter's serve. It is everywhere, like hammering a nail.
How is a hammer used? You start holding it straight up, lift up straight right directly above the nail. Then drop the hammer head straight down as the hand goes down and hand/handle back away. How about the pick? same thing.
If we can agree on this, some PA, is at play during most swinging motion, then we can discuss how to harness it.
Well not exactly, if understanding the optimum motion path which enable us to program ourselves then great. The biggest problem is instruction and human body is not so easy to program. Well, let's go back, we actually do not know exactly what motion is optimum. And then what is optimum. What is good for max speed is not necessarily good for control, as the previous post nicely pointed out.
As someone who teaches physics in high school, I want to point out that, the end result is actually the speed we want. We actually want a high racket head speed moving translationally at contact, because we want control and not a slap. You can have a small acceleration for longer time or large acceleration and shorter time, both can achieve a high speed. It is a wonderful world, we do not all have to do it the same way.
My thought at this point is... focus on the swing of the racket, not your body. Feel the swing, play around with it. Most of all have fun!