where'd the bent arm come from anyway?

[oliensis]

Here's another video from the same source:

http://www.youtube.com/watch?v=98mVxe1lBKU

If you don't want to wach the whole 5:47 video on batting, skip ahead to about 4:50 and let it run. The commentator addresses the myth of "extending the arms" in a baseball swing.

David Wright, David Ortiz, Ken Griffey Jr, etc., all hitting a BASEBALL w/ a double bend in rear arm. Pretty good power on all of them. Go figure!

[oliensis]

Don,
Well put.
There are fulcrums and complexities in the kinetic chain that make it complex as hell.

Would the longest whip give you the biggest snap? (Some towels are too big to snap effectively.)

Do you hammer a nail with a straight arm? Why not?
Why is a 9 iron shorter than a driver?
Why don't pros play with 29" rackets if a longer lever is optimal?
Why don't baseball players hit with 41" bats and stand as far from home plate as possible?

Here's Federer hitting a mid-court forehand where he clearly had plenty of time to set up, move to the ball (several steps) and rip it with whatever stroke he wanted:

http://www.tennisplayer.net/members/strokearchive/pro_men/rogerfederer/rogerfederer_forehand/rogerfederer_fh_short/rogerfederer_fh_short.html?FedererFHShortSide1.mov

Looks like a modest double bend. Why not straight arm? Maybe because, given that he's rolling the racket over the ball and driving either inside in or a little bit cross court, he's using the elbow as a fulcrum, to some extent, from which he is rolling the stroke over in order to generate the particular direction and spin he's going for.

Of course, you want to use the longest lever you can within the parameters of the shot you're trying to hit, but, only up to a point....Watch this video:

The commentator is talking about similar issues for baseball swings. He's discussing the lead arm. But look at the rear arm. A lot of damn good hitters are hitting the baseball (which swing putatively should have extended arms) with double bend structure in rear arm (analagous to forehand).

http://www.youtube.com/watch?v=vS3HTHXspmk&feature=related

The difference in the length of the lever between a straight-arm and double-bend forehand may be between 1 and 3 inches. That difference is not inconsequential, but is often outweighed by numerous other factors in reality.

Of course, setting up for the ball with good distance, and keen awareness of a good contact point are very important...probably more important than the specifics of stroke mechanics in many ways.

[uspta990770809]

Is the arm the real lever arm?

Carrerakent,
I have seen bits and pieces of many of your responses on various threads the last couple of weeks and I certainly haven't seen them all, but the general theory I get is at least part of your teaching approach (I don't want to say system because I think you would jump all over that limiting your students) is that you should use whatever leverage you have and take advantage of the increased velocity a straight arm gives the racket head. I've seen the parts about the right contact point and athletic moves, but in general, I get the sense you are saying anyone would be a fool to try to use a bent-arm shorter lever arm to hit the ball if he could possibly use the full length of his arm. But if that were the case, wouldn't we all have gravitated to the extended length rackets that were introduced a few years ago? The serve is different because you have the ball in your hand, but because of pronation, we don't even hit that with a truly "straight" arm from the shoulder. But players are definitely getting taller in the pro ranks. But I digress. Let's stay with the forehand.

My belief is that tennis is and always has been defined by C.A.P.: Consistency, Accuracy and Power. The more consistent player will always win. The more accurate player takes his opponents consistency away from him by forcing him to play from positions in which he loses his consistency (i.e. on the run). The more powerful player wins by forcing the more consistent player to play at a speed at which he is no longer more consistent. As a result, tennis (as much as it has become a game of power in recent years) is not simply a game of power. However, spin and racket technology has equalized consistency to a large degree to the point where accuracy and power have become more important than ever before. This is, at least, my belief.

But coming back to the power generated by the longer lever arm and arc of the straight arm, (and I need some help from the biomechanists here) isn't the actual lever arm the imaginary lever arm from the contact point to the axis about which this motion is rotating. Therefore it is not as simple as the straight arm is the most powerful position to hit the ball. Before we get to the fundamental question of diminishing returns on an ever widening and increasing arc and lever arm in terms of reduced accuracy and consistency (or a heavier racquet for that matter), there is a question of whether the shoulders are part of the line from contact point to the center axis of rotation of the swing. I don't know the answer. I'm trying to propose it is not even as simple as straight arm vs bent arm. On the one-handed backhand, you could argue a straight line from the hitting shoulder where the axis of rotation is located (most of the time). But on the forehand, the hitting shoulder is the back shoulder most of the time and only gets into the line of the lever arm right at contact. You could visualize an axis of rotation through the left shoulder/hip/foot for a right hander hitting a square stance forehand with a straight arm, but we do not actually hit the ball with a truly circular motion around that axis like a hammer thrower. We generate racket head speed gradually with the assistance of a gravity drop (no charge from the cosmos!), accelerating from what I think you call the "sweet spot" behind the ball. While the body can only generate forces with torques, the forces that we create to actually hit the ball are very briefly linear. in fact, the racket touches the ball for a few inches on a 60 mph shot (88 fps x 1/250 sec x 12 in/ft). If we were truly moving the racket in an arc, consistency and accuracy would be impossible. Instead, we try to create a hitting "zone" which is probably much greater than 3 or 4 inches so that we have some margin of error and can be somewhat consistent and accurate. Because of this constraint, simply hitting at the longest possible lever arm position with a straight arm would seem to be too difficult a goal. Nice for creatures from another galaxy like Nadal and Federer (you knew that, right?!), but a little too challenging for the rest of us. On the other hand, the human ability to coordinate things is truly otherworldly and you say you are having great success with your methodology with even 80 year olds. But I feel when the ball starts to move around at the speed of world class shots, you have to be able to adapt and a "bent-arm" configuration gives you the most flexibility and ability to compensate for incomplete (not necessarily poor) footwork. And if the lever arm is actually to the axis of rotation, how much do you actually give up in power if it means you are able to keep the racket moving along that 4 inches of contact zone in a straight line delivering power to the ball the whole way (Brian, am I wrong here? Is all the power done in the first 2 milliseconds? I hope you will chime in.) In fact, I would question whether in even a "straight-arm" forehand, whether that arm is part of the "effective lever arm" from the contact point to the center axis of rotation or if the racket and hitting arm are actually parts of a triangular structure that is created by the shoulders, the hitting arm and the racket, and the imaginary "effective lever arm". My vocabulary may be way off. I would appreciate any help from you biomechanists out there. My background as and engineering school graduate and a chiropractor gives me a little bit of technical understanding, but I am no biomechanist; mostly just a struggling tennis pro dealing with a few very talented kids and a lot more people who are just normally talented.

That's enough. Hope that gets a little bit of a discussion started.
don

[johnyandell]

Uh, again as we've discussed a few times, it's not a coaches' conspiracy. Showing video of other sports, including throwing dirt clods, is interesting but probably irrelevant.

One point overlooked is that Federer himself hits about 1/3 of his forehands double bend, and Nadal does it on a percentage.

The reason players do it is that it works for them. As you quoted the site--actually it was something I said--coaches follow players.

Sampras, Agassi, Djokovic, Del Potro, Federer, Berdych, Soderling, Murray, Jo Willie--to mention just a small number who all use this structure with huge forehands.

I'm not sure how you can call it bizarre when it's the overwhelming norm. You have certain feelings but is that right to impose on the entire tennis world? The answer is? And again maybe it is the future--and maybe not. If you really want to have credibility you'll have to explain how the average player should somehow have a more "advanced" technique used by only a few elite pro players.

[carrerakent]

Has anyone ever asked why tennis players, coaches, and teaching pros think a bent arm is a rational way to hit a tennis ball?

Look at other sports and neighborhoods and how it has been known for decades and taught at all levels, that the extension of the arm at the shoulder all the way to the wrist/hand completes the natural biomechanical motion of hurling or hitting an object. Javelin, discus, football, baseball, hockey, golf, throwing rocks at cars or cats, the list goes on and on of sports where they've known for decades... and our tennis friends are still confused. (See attached images)

Any kid that grew up throwing rocks, dirt clods, or a baseball knows that you just naturally extend to the point of release. So why is it that tennis players got the bright idea that in order to hit harder we have to shorten our arm and muscles.

And then a couple of guys come along recently that look like they are dragging a sack of potatoes with their "straight arm" forehand, they have a couple of good weeks of tennis and tennis enthusiasts wonder if that is the next evolution.

I really would like some help in understanding how this bizarre phenomenon came about in tennis only. Was it Jim Courier? He sure drug his arm through the hitting area like he was pulling a piano behind him.

I think it all came about because tennis players came to decide after over 100 years that it was okay to actually explode with all of their might into a ball (novel concept since athletes had been doing that forever already) but since tennis players have such limiting boundaries in which they can hit (the court), they didn't know how to trust their new found athleticism to not hurl the ball into the stands and they didn't understand how to perfectly align their bodies to get an extended contact over and over, so they evolved into a guiding motion.

Maybe the whole white long pants and skirts thing just got tennis off to a very very very slow beginning of confusion as to whether this was a sport or not. I guess it doesn't really matter...does it?