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very,very interesting and useful article.Hope reading more articles from this coach.
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another article is coming
Thanks for the positive feedback, Zakito. The follow-up article that gets into timing more than the racket head is coming up soon. It's great when people let John know they like this article. He pays attention!Comment
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I like the way this site is always improving, feel like my money is well spent
This year I subscribed also another site of tennis coaching I'm not obviously mentioning: bleahhh,It's awful compared to tennisplayer: 6/0 6/0 for John.
Glad your next article is coming soon.Comment
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Momentum and racquet head
Great article on timing, and I think I understand, and agree with, most everything said. What I don't understand is the concept of racquet head momentum, and maybe I just don't understand Bill Tilden when he says it's only the racquet head which connects with the ball. I tend to think of the body and racquet as being connected, basically a single unit, with the body contributing the bulk of the mass in the creation of momentum. Is it Tilden's position that at the point of contact the racquet is no longer effectively attached to the hands? If so, then wouldn't the velocity of the racquet head have to be very high to create the necessary momentum to counteract the momentum of the ball?
And, if I take Tilden literally and only the racquet head is involved, then I must have lost touch with the racquet and now have no feel whatsoever. I've tossed the racquet head at the ball and at some point can only hope for the best! Hmm, I don't like that idea!
Do you know of anyone who has ever explored the idea of "effective" mass, which would take into account the size of the person hitting, the rigidity of the grip, maybe if the person is positioned strongly behind the ball versus reaching out to the side, etc.?
Thanks for the article and the drills!
MikeComment
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There's a couple of points to be made in response to your question, Mike. First of all, excuse me for being a little slow in a response. It's been a busy week.Originally posted by uspta170296952 View Post
Momentum is mass times velocity and the mass of the racket head is approx. 10x that of the ball (or more). It is not traveling as fast as the ball, but it is traveling almost as fast as the ball, so there is no great question of overcoming the momentum of the oncoming ball, as long as the racket head is moving in the right direction. That's how you move a volley off a fast ball with a short swing, if you have your volley swing moving in the right direction at impact.
I don't think Tilden was talking as much about the racket head momentum as he was about the fact that the racket head is what actually physically touches the ball and there is certainly no getting around it. But (and I haven't seen that book in a long time) he was also inferring something about the momentum of the swing.
As far as your concept of effective mass, I need some input from the biomechanists out there, but there are some fundamental principles that apply.
We hit the ball with levers. Long levers are more powerful than short levers. But remember how Archimedes said he could move the world with a lever if he had a place to put his fulcrum. Your body weight and planting your transfered weight on the front foot makes your "fulcrum" or pivot point more secure for you to swing around. But increased weight may be more stable, but the law of diminishing returns takes effect (or tennis champs would look like interior linemen). Tennis is still more about movement than about how hard you can hit the ball. Also important to note, when you snap your wrist on a forehand, you move the fulcrum to the wrist or basically the end of the handle, whereas when you swing with one big piece pivoting around the center of your body, the lever arm is much longer and the "fulcrum" is somewhere deep in your chest (almost twice as long as from the end of the racket).
As for releasing the racket, you should be able to release the racket right at impact and still have a pretty good shot. Your grip should be snug to control the racket rather than tight. When you hold on tight, your muscles act like brakes. What you really want is to accelerate through the impact (even on a slow shot) so that you can keep the ball that little bit more (at least in feel). One of the great drills is to have someone try the two-finger or middle finger and thumb hit, especially with weaker players who are struggling to get any power. Suddenly, they actually hit the ball faster with this grip because they must use the momentum of the racket head. Maybe not on the first 2 or 3 shots, but almost everyone gets the idea within a few shots.
More food for thought: do you want your surgeon to hold the scalpel tight, or do you want him to let the blade do the work and hold it with absolute control and accuracy (and very lightly)? The racket should be your scalpel. Control it, don't strangle it!
That's all I have time for right now. I hope that answers some of your questions. Perhaps someone else will chime in and explain these points in a little more technical terms.
donComment
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