Originally Posted by maxpotapov
... it's not just arithmetic sum, but there's a progression in how parts align and interact to create optimal conditions for fastest racquet acceleration at the point of impact.
I would also argue, that even if PROPER coordination/rotation of lower/upper body contributes only 15% to the racquet speed, LACK THEREOF might cause a 40% slow down.
Originally Posted by toly
... I think that 15% contribution to the racquet speed is not very important for the reason that we have to waste a lot of energy to create fast rotation of 130 - 200 pounds body. IMO it is better first to concentrate on arm actions and then on the body. The arm is much more important. In tennis everything is important, however with varying degrees of importance.
Don't really know exactly what Brian Elliot means by this 15% contribution. However, what I've read of his published study, he seems to indicate that a full well-coordinated kinetic chain is important to high level tennis strokes. In light of this, the 15% figure appears to be rather misleading. It suggests to some that the contributions from the legs, hips, core and trunk are not all that important. I do not believe that this is the case. maxpotapov
's statements above could have some merit.
If the contributions from the links are really not all that important, then why do high level players "waste a lot of energy" employing those links on most of their shots? Often, they are playing or practicing for 3-5 hours or more a day. It would seem foolish for them to "waste energy" for an extended period of time if the returns are trivial or unimportant.
It is my belief that using the legs, hips, torso, etc reduces stress to the shoulder and rotator groups. We transfer "energy" to the shoulder and arm from the previous links rather than have the shoulder (and arm) generate it all own its own. The leg muscles are much stronger that the shoulder and arm muscles. The legs, hips and torso also represent larger masses (with greater rotational inertia) than the shoulder/arm and racket. So when we transfer the energy from those larger parts to the shoulder, it allows the arms to accelerate more easily (with less stress).
I am keenly aware of the stresses in my own shoulder. For the past few years I've had somewhat limited shoulder function (from an old volleyball injury to the rotator groups -- some 20 yrs ago). If I prepare late for a shot and try to rely solely on my shoulder/rotators to swing my racket, I experience significant pain. However, when I employ my legs, hips and torso, I can get my shoulder/arm moving quite fast without pain.