Soderling's Backhand; Video Available?

[uspta146749877]

2HBH of Roddick

I talked about some of the other technical aspects of the modern 2hbh in my longer post which got eaten by the internet, but basically I agree that you need some flexibility in the wrists to get the whipping action which will give you some additional pace and topspin. I don't think Roddick does this very well and that's one reason his backhand isn't that great.

I also agree that many pros have most of these technical aspects down (Roddick excepted), but I still think that those that have the hardest backhands are the ones who are able to get their body weight into their shots most effectively. I don't think it's any coincidence that the guy with the hardest 2hbh is also the heaviest guy at the top of the game (Nalbandian). I've also heard that he uses an insanely heavy racket. Murray's backhand is great, but he usually uses control and finesse not pace, so he's using his wrists more than his body weight.

In the case of Roddick his 2HBH grip is the issue.see Macci

[crass_lawner]

In the case of Roddick his 2HBH grip is the issue.see Macci

One of them. He also doesn't use his bodyweight, same thing with his forehand, he's all arm. So he can't get that k-chain or whatever going, that's why it always looks like he putting so much effort into his shots and yet still hitting mid-paced floaters. If he does rotate his body, it's because the momentum of his arm/racket turn his body around, not the other way around as it should be (as oliensis's post mentioned). It's the same physics that result in the supersonic speeds at the tip of a bullwhip. If it were just his backhand grip that was the problem then his forehand would be fine, because there are plenty of players w western grips who can generate tons of pace (Kuznetzova, Mathieu), but since he doesn't use his bodyweight to start the "k-chain" his forehand suffers from the same problem as his backhand.

Speaking of players with western grips who generate tons of pace, any chance of getting a video of Andreev's forehand on this site? I've never seen a slo-mo version and I'd be curious to see how it works. I know it's very unorthodox and he not a top ranked player, but sometimes I think it's the unorthodox ones that are the most interesting.

[johnyandell]

Uh, sorry, but the concept of body weight is of dubious biomechanical significance.

You don't hit the ball with your body, hit the ball with the racket and the speed and path of the racket is what determines the path of the ball, not how much you weigh. I understand it at the level of metaphor. But I have been on the court with 12 year old girls who way 90lbs and hit the ball way harder than 99% of men club players.

What seems to matter is the sequencing of the key positions. It's the rotation of the segments, the speed of the rotation, and the positions of the segments.

[crass_lawner]

No need to be sorry. It's just simple physics, but since physics is kind of abstract it can be hard to recognize. It's just a matter of momentum, which is a product of speed and weight. Therefore, given the same speed, an object with more weight is going to impart more momentum on anything it comes into contact with. Therefore if Nalbandian swings his racket at the same speed (and with the same technique) as someone else, he is going to impart more momentum on the tennis ball.

You mention the "speed of the segments" but don't recognize that force is not just a result of speed, but speed and weight. Why do pros use heavier rackets than amateurs? Because they recognize that weight is vital to imparting force on the ball (and they have the strength to do it). So it's obvious that you need weight behind the tennis ball, but how does body weight translate into weight behind the tennis ball? Well it's all part of the "k-chain" that someone else mentioned and you (John) kind of make reference to and is briefly explained on this usta webpage: http://www.playerdevelopment.usta.co...390&itype=7418. This chain acts on the same principles as a whip: http://www.worldkungfu.com/whip.html or an ocean wave. The first link has more mass and little speed, and the last link has the least mass and the most speed. As energy is transferred down the chain, it is converted from mass to speed.

Why is hip and shoulder rotation so important? That's the body's way of creating torque which is then transferred to the arm, wrist, racket, etc. I'm sure you understand this, but if you understand this then you should understand that the more force created by the first link in this chain, the more force released in the last link, and as I've explained earlier, the force in question (momentum) is a product of weight and speed, therefore, given the same speed, the more weight the first link has, the more force will be transferred to the last link (the tennis racket).

[johnyandell]

Well the weight of the racket yes. Do you include the weight of the arm? It's a fascinating question but I don't think body weight enters into the equation directly. If that was a direct corelation you'd see NFL linemen winning Slams.

And in the equation I forget the exact ratio, but speed is the more important component. Somewhere there in Rod Cross's book.

[oliensis]

As a martial artist this question of how to transfer force has been interesting to me for almost 30 years. The formula is

force = mass * acceleration
(acceleration is different than speed, it's the rate of change of the speed)

The formula for acceleration is here (it's a little more complicated).

http://wiki.answers.com/Q/What_is_the_proper_formula_used_to_calculate_acceleration

I don't know, but I suspect that "mass" must be considered to be the mass of the object that is "ballistic." By which I mean, the mass of whatever is the object that's hitting the target (in tennis it's the ball, in breaking boards it's, e.g., the fist--or not...more on this below). Or maybe the best term is to call it the "hitting lever."

If you throw a ball, the ball delivers only the mass (M) of the ball times its acceleration. But how about if you have a giant rock suspended from a frame by a rope and you pull the rock back, like a swing, and then release it. The the M is the M of the rock and the acceleration is complicated by the fact that it's moving along the circumference of a circle, which makes it angular acceleration, measured in radians/sec^2.

Here's the formula: http://en.wikipedia.org/wiki/Angular_acceleration

Now, suppose that the rock was an "L-shaped" battering ram. The mass of the entire L-shaped object would be the M in the equation, not just the mass of part of that object. So, in this case, the mass of the hitting lever is not just the part of the lever that was "in line" with the diretction of the force being deliverd. Why bring this up?...it's analagous to the mass of the hitting lever when throwing a "hook" in boxing. (The arm is an L-shaped hitting lever...as it is in a double-bend forehand--or in that case it may be a Z-shaped hitting lever, assuming that the wrist and elbow are locked during the strike.)

Ever notice how boxers' shoulders sort of "release" their whole arm when they "let the punch go?" So, when the punch is thrown, the mass of the hitting lever is not just the first, and not just the fist + forearm. I think that for a "hook" at least some part of the arm and shoulder are "ballistic" (should be counted as the hitting lever, and are moving as one w/ the fist, so that when the fist hits the other boxer the added mass of arm and shoulder are part of the force transferred).

How about with a very close body blow/hook punch where you can see the boxer get his hip way into the punch and the hitter sort of tightens up again on impact (like when a karateka tightens his center and all musculo-skeletal connections to the fist at impact when he "kiapps" (yells).) The M may be need to account for more than just the arm and shoulder in this case.

If, biomechanically, the force of a punch were just a function of the acceleration of the mass of the fist at impact, then a jab would almost always be more powerful than a hook or a cross. But that's not the case. The accleeration of the mass of the fist is only one small component of what is probably a very complicated equation that measures the force of the punch.

I suspect that biomechanical studies will discover that people who can throw powerful punches and hit powerful ground strokes have a knack for causing the ballistic lever (fist or racquet) to have more mass, functionally speaking, in the F=M * A equation.

If you have any doubt about this, imagine trying to break a board with a left jab. Now imagine trying to break a board with a long right cross. Now imagine trying to break a board with a short right cross with the target only about 12-16" in front of you. From years of experience I can tell you that the long jab and long cross are traveling faster than the short cross. But that the short cross is much easier to break boards with. Why? Because it's easier to put more M into the short cross. (Is the only dif. acceleration? Or mightn't functional mass of the hitting lever enter in? I think so.)

Now, how about when you punch a forehand volley, using almost no arm and shoulder movement but a big lunging step forward and a very firm wrist and elbow? I've seen Boris Becker absolute crush a volley like that. Why? Lots of M.

I wonder whether the double bend forehand might benefit in terms of power (relative to the straight-arm forehand) from the relative ease of transferring M...where the straight-arm makes it easier to have a larger A because of the longer lever.

I may be completely wrong on this, and I'm happy to hear diverging opinion/argument/information. But, to close, I'll add one anecdote: I once got to watch Jimmy Connors warm up on a clay court (in Manhattan about 10 years ago). He was stroking the ball very very slowly compared to a # of other senior pros (Pernfors, Borg, McEnroe et al), but the ball was absolutely jumping off his racquet. The only thing I could see that could account for how the ball was jumping was a load of M moving into the ball. Again, I could be wrong, but I think that his "hitting lever" was functionally very heavy.

[airforce1]

As a martial artist this question of how to transfer force has been interesting to me for almost 30 years. The formula is

force = mass * acceleration
(acceleration is different than speed, it's the rate of change of the speed)

The formula for acceleration is here (it's a little more complicated).

http://wiki.answers.com/Q/What_is_the_proper_formula_used_to_calculate_acceleration

I don't know, but I suspect that "mass" must be considered to be the mass of the object that is "ballistic." By which I mean, the mass of whatever is the object that's hitting the target (in tennis it's the ball, in breaking boards it's, e.g., the fist--or not...more on this below). Or maybe the best term is to call it the "hitting lever."

If you throw a ball, the ball delivers only the mass (M) of the ball times its acceleration. But how about if you have a giant rock suspended from a frame by a rope and you pull the rock back, like a swing, and then release it. The the M is the M of the rock and the acceleration is complicated by the fact that it's moving along the circumference of a circle, which makes it angular acceleration, measured in radians/sec^2.

Here's the formula: http://en.wikipedia.org/wiki/Angular_acceleration

Now, suppose that the rock was an "L-shaped" battering ram. The mass of the entire L-shaped object would be the M in the equation, not just the mass of part of that object. So, in this case, the mass of the hitting lever is not just the part of the lever that was "in line" with the diretction of the force being deliverd. Why bring this up?...it's analagous to the mass of the hitting lever when throwing a "hook" in boxing. (The arm is an L-shaped hitting lever...as it is in a double-bend forehand--or in that case it may be a Z-shaped hitting lever, assuming that the wrist and elbow are locked during the strike.)

Ever notice how boxers' shoulders sort of "release" their whole arm when they "let the punch go?" So, when the punch is thrown, the mass of the hitting lever is not just the first, and not just the fist + forearm. I think that for a "hook" at least some part of the arm and shoulder are "ballistic" (should be counted as the hitting lever, and are moving as one w/ the fist, so that when the fist hits the other boxer the added mass of arm and shoulder are part of the force transferred).

How about with a very close body blow/hook punch where you can see the boxer get his hip way into the punch and the hitter sort of tightens up again on impact (like when a karateka tightens his center and all musculo-skeletal connections to the fist at impact when he "kiapps" (yells).) The M may be need to account for more than just the arm and shoulder in this case.

If, biomechanically, the force of a punch were just a function of the acceleration of the mass of the fist at impact, then a jab would almost always be more powerful than a hook or a cross. But that's not the case. The accleeration of the mass of the fist is only one small component of what is probably a very complicated equation that measures the force of the punch.

I suspect that biomechanical studies will discover that people who can throw powerful punches and hit powerful ground strokes have a knack for causing the ballistic lever (fist or racquet) to have more mass, functionally speaking, in the F=M * A equation.

If you have any doubt about this, imagine trying to break a board with a left jab. Now imagine trying to break a board with a long right cross. Now imagine trying to break a board with a short right cross with the target only about 12-16" in front of you. From years of experience I can tell you that the long jab and long cross are traveling faster than the short cross. But that the short cross is much easier to break boards with. Why? Because it's easier to put more M into the short cross. (Is the only dif. acceleration? Or mightn't functional mass of the hitting lever enter in? I think so.)

Now, how about when you punch a forehand volley, using almost no arm and shoulder movement but a big lunging step forward and a very firm wrist and elbow? I've seen Boris Becker absolute crush a volley like that. Why? Lots of M.

I wonder whether the double bend forehand might benefit in terms of power (relative to the straight-arm forehand) from the relative ease of transferring M...where the straight-arm makes it easier to have a larger A because of the longer lever.

I may be completely wrong on this, and I'm happy to hear diverging opinion/argument/information. But, to close, I'll add one anecdote: I once got to watch Jimmy Connors warm up on a clay court (in Manhattan about 10 years ago). He was stroking the ball very very slowly compared to a # of other senior pros (Pernfors, Borg, McEnroe et al), but the ball was absolutely jumping off his racquet. The only thing I could see that could account for how the ball was jumping was a load of M moving into the ball. Again, I could be wrong, but I think that his "hitting lever" was functionally very heavy.

looking at Soderling BH in video of the match tonite, it would seem to support what you are saying, as his bh seemed to be quite compact on the big winners he hit with it. really reminded me of the Agassi return of serve, short and direct.

the bh return winners accounted for both of the 5th set brk points converted by Soderling.

[crass_lawner]

...
I may be completely wrong on this, and I'm happy to hear diverging opinion/argument/information. But, to close, I'll add one anecdote: I once got to watch Jimmy Connors warm up on a clay court (in Manhattan about 10 years ago). He was stroking the ball very very slowly compared to a # of other senior pros (Pernfors, Borg, McEnroe et al), but the ball was absolutely jumping off his racquet. The only thing I could see that could account for how the ball was jumping was a load of M moving into the ball. Again, I could be wrong, but I think that his "hitting lever" was functionally very heavy.

Sorry it's 4 in the morning and I've been drinking so I was unable to closely read most of your post, but your mention of Connors piqued my interest. I almost mentioned him in my post. He was very famous for "throwing" his whole body into his shots, and if you see a slo-mo of some of his service returns you can really get a sense of this (maybe there's some on this site I haven't checked). Like you said, I think this is a real good example of the effect of mass as opposed to just speed (or acceleration) in imparting force on the ball. I've seen Simon hit some backhands that look really similar to these Connors backhands as well.

I also was going to mention the issue of players with excessive mass (like NFL linemen or just plain fat guys) that John raised in his post. Obviously weight is just one of many factors that are going to contribute to a hard well hit backhand. But perhaps if the sport of tennis were just a matter of hitting the hardest two handed backhands that land in the court then most tennis players would look more like NFL linemen, but unfortunately for them a real tennis player must then use that same body to run back and forth and up and down on an asphalt court for hours on end, something that very heavy people would have trouble doing. And I would also guess that just hitting a pro-level two-handed backhand requires a level of precision, flexibility, timing, and balance that many NFL linemen would have trouble with.

And yes, the weight of the arm does matter, but probably not as much as the weight of the first link in the chain (the players body) which initiates the whole sequence. I'm not a physicist, but I would imagine that given a certain weight for the first link in the chain (a player's body), there would be an ideal weight ratio (progressively smaller) corresponding to each of the subsequent chains, so hypothetically the arm could be too heavy, too light, or just right according to this ratio.

Of course as the usta page I linked to earlier mentioned, the first link in the chain is really the feet and legs, because by pushing off of the ground they are responsible for creating the speed or rate of acceleration (in some combination of forward and rotational momentum) that the body (dependent on its mass of course) will attain, but that's not necessarily important to my overall point.

[johnyandell]

Guys,

All this is just too hypothetical for me. Very difficult to understand and impossible to assess. So I am just going to bow out. The fact is when we start talking formulas and physics we've verged over into an area where measurement and data is required. And that we don't have. Just my personal perspective, but not sure how valuable the why is as compared with the how, anyway. Intuitively working with players it's obvious the whole weight issue is a non factor, but proving it is beyond my expertise and I am afraid also that of the posters here. So carry on if you wish. I've stated my views once and that's enough.. And by the way, for future reference, my name is John--only my wife calls me Johnny please.

[crass_lawner]

Guys,

All this is just too hypothetical for me. Very difficult to understand and impossible to assess. So I am just going to bow out. The fact is when we start talking formulas and physics we've verged over into an area where measurement and data is required. And that we don't have. Just my personal perspective, but not sure how valuable the why is as compared with the how, anyway. Intuitively working with players it's obvious the whole weight issue is a non factor, but proving it is beyond my expertise and I am afraid also that of the posters here. So carry on if you wish. I've stated my views once and that's enough.. And by the way, for future reference, my name is John--only my wife calls me Johnny please.

Oops sorry I misread your name. I kind of figured this was a pointless aspect of the game to talk about when I began, but I just couldn't help myself. And I just can't help myself from giving one last metaphor.

Picture a tennis player as a large top spinning in the direction of body rotation. This top has a little paddle sticking out of the side of it so that when a small ball comes towards it, the paddle hits it on its way around a revolution. Wouldn't you agree that the force with which this top hits the ball is dependent upon the weight of the top? That's essentially the exact same thing that's going on when a tennis player hits a ball.

The example I just gave ignores the "whip" aspects of racket acceleration, but gives a simpler demonstration of what happens when a player hits the ball by more simply illustrating the (force = mass * acceleration) formula. Yes it's "theoretical" in a way, but I really don't think it's so complicated as to be outside of the realm of comprehension.

As for young players, I think their extreme flexibility, coordination, reflexes, mobility and in the case of top juniors, training and technique simply allow them to compensate for their lack of mass by transferring their energy from their feet to their racket more efficiently than older, heavier players who aren't as good.

[airforce1]

Guys,

All this is just too hypothetical for me. Very difficult to understand and impossible to assess.

Intuitively working with players it's obvious the whole weight issue is a non factor, but proving it is beyond my expertise and I am afraid also that of the posters here.

I don't think you mean any disrespect John, but you might want to consider that this clearly is not the case with many of your readers and posters.

I personally know several of the phd posters who have more than one advanced degree, and on subjects form Aerospace engineering and physics, to Kinesiology. Clearly we have several Martial Arts instructors, along with former college and pro athletes.

Also you have mentioned your trust in numbers and measurements, but we have to remember that the measurements are only as good as the one doing the measuring and the methods employed. Many times tech folks who measure are not the same ones who do the innovative thinking either. Often, good ole experience is the basis for new and innovative ideas, and numbers proving the hypothesis come years later. Einstein worked out his ideas based on how he saw things working, then he and others were able to build proofs and observations to support them over the ensuing decades. So lets don't write off folks gut ideas too quickly.

[johnyandell]

No, my point is this--I don't think it makes sense or is productive to make quantitative arguments without having quantitative data. You get to the point of he said versus he said very quickly. Like I said, carry on, but it's not something that seems valuable from my point of view. If Brian comes along and eventually lays out some framework to actually evaluate these kinds of claims, great. But even then there is still the issue of why versus how. I'm not sure an explanation of the kinetic chain is the info the average player needs (and higher level players even more so) to improve their forehand...

[BrianGordon]

I don't think you mean any disrespect John, but you might want to consider that this clearly is not the case with many of your readers and posters.

I agree that John meant no disrespect, but a reasonable person would have to conclude you did. As I am the only person around here (and one of handful on the planet) that produces quantitative data on tennis strokes I consider your post offensive.

Also you have mentioned your trust in numbers and measurements, but we have to remember that the measurements are only as good as the one doing the measuring and the methods employed.

So… we’ve moved on from inferior subjects to questioning credentials and methods. OK, I’m here to learn like everyone else, so please enlighten me as to the proper training and methodology to produce viable measurements – be specific please.

Many times tech folks who measure are not the same ones who do the innovative thinking either.

There is no differentiation in sport biomechanics.

Often, good ole experience is the basis for new and innovative ideas, and numbers proving the hypothesis come years later.

Tempting but - nah.

Einstein worked out his ideas based on how he saw things working, then he and others were able to build proofs and observations to support them over the ensuing decades. So lets don't write off folks gut ideas too quickly.

Einstein never confused mass with weight, speed with acceleration, associated f=ma with rotational motion, described mass and speed as transferable forms of energy, abstracted the kinetic chain into nothingness, or considered weight transfer a mechanical concept, to name a few.

To the point of at least the latter part of this thread, getting the weight behind the ball or transferring weight into the ball is a coaching concept. The mechanical concept is motion of the center of mass and associated linear momentum. In both cases the impact on racquet speed (shot power) at contact is so negligible I don’t even report it when assessing contributions to racquet head velocity on ground strokes.

This makes sense intuitively on a backhand (primarily neutral/square/closed stance) stroke where the contact of the front foot on the ground and impending leg drive, near the end of the backswing and during the forward swing respectively, serve to stop any forward linear momentum of the body. This is by design to generate angular momentum for the body.

The case put forth by oliensis of effective mass is more compelling but really just represents different system definitions. Differences in speed of the end point across different techniques in the examples cited will be due to a combination of altered range of motion, altered joint rotation contributions, altered muscle moment arms and associated muscle lengths, and changes in the velocity of muscular contraction needed to rotate the joints among others. The primary difference between a straight arm forehand and the double bend for example, is not one of effective mass, but rather one due to alteration of the way upper arm rotations contribute to racquet velocity and what that means for other joint rotations.

Finally, if the velocity of the body center of mass is linked to a large proportion of the racquet head velocity, as on a classical volley due to minimal joint motion, getting “the weight” behind the ball can be important to racquet speed at contact – so I guess it is no coincidence that the timing of the step with the front leg relative to contact is radically different than on a ground stroke.

[airforce1]

No, my point is this--I don't think it makes sense or is productive to make quantitative arguments without having quantitative data. You get to the point of he said versus he said very quickly. Like I said, carry on, but it's not something that seems valuable from my point of view. If Brian comes along and eventually lays out some framework to actually evaluate these kinds of claims, great. But even then there is still the issue of why versus how. I'm not sure an explanation of the kinetic chain is the info the average player needs (and higher level players even more so) to improve their forehand...

You make very good points as always. I can clearly see why you would step back given your point of view.
My main point is there is no need to pass judgement that this is beyond the scope of your very educated readers, in the process of pushing back.
My other point is that while BG does outstanding work that can be very useful in attempting to sort things out, this work is still subject to errors in measurement, as well as data interpretation. I'm not saying it isn't worth his valuable effort, just that these evaluations are not the end all some seem to think. Even if most of it is very accurate (if ever done) it is decades behind the ideas and discussions that have led to it.

So while I respect your opinions and choice not to participate in the discussion that you can't appreciate, I can't agree with your assessment that it is beyond the scope of the posters and better to just wait on a study that may never come.

[johnyandell]

Uh, if beyond the scope means there is no hard evidence to support it, sure, beyond the scope. It's fun to speculate about how the body works. I do it all the time. That's different though than using scientific and biomechanical terms that aren't tied to actual analysis of the motions under discussion. That's where I think we can get out of our depth. I've been chastened by that experience many times! Actually wrote once that the ball accelerates after the bounce on the court...