View Single Post
Old 03-02-2011, 11:27 PM   #50
sennoc
Semi-Pro
 
Join Date: Mar 2009
Posts: 406
Default

Quote:
Originally Posted by salsainglesa View Post
Sennoc no disrispect here, but if serve was only done by the hand then that would be true, but there are more axis and levers than that.
There is more, I agree. Much more, in reality. But this is a scientific fact: iternal rotation of upper arm generates 40% of energy, horizontal flexion 15-25% depending on the type of serve. Contribution of palm ulnar flexion is ca. 30% at power serves and negligible at kick serves, while ulnar flexion generates ca. 20% at kick serves and almost nothing at power serves.

People believe in the magical role of other parts of kinetic chain because they usually watch the best servers. They (best pros) really use many many other elements, so many that they sum to important values. But what about players like Wawrinka? His kinetic chain is very short but he serves quite well. Does he use magical powers of the other universes?

You also have to remember that kinetic energy of racquet's head is not a simple sum of energies generated at every part of kinetic chain. This energies contribute to ca. 70% of kinetic energy of the stroke. Just 70%. The rest - ca. 30% of the sum!!! - is generated by energy transfer along kinetic chain. I have a beautiful picture here from one of the scientific papers, but I can't attach the file and I'm too lazy to find a host. But I promise I'll post it here - in hours after LeeD's first video from the court

And here is the most funny part. If you want to have an access to this "additional" 30%, you have to use your kinetic chain in a way similar to a whip. The problem with amateur tennis players is that they do not use this method. But if you start working on proper serve technique, you unintentionally learn how to use better energy transfer! So, when a player starts to think about "upper arm rotation", about "pronation", he begins to move energy along kinetic chain! "Wow!" - he thinks - "that pronation is a really huge source of energy!".

Funny, don't you think?

Toly, give me please some time.

Last edited by sennoc : 03-02-2011 at 11:29 PM.
sennoc is offline   Reply With Quote