No "Pet The Dog" on 2HBH?

[julian]

Originally Posted by WildVolley

Julian,

Looking at the video of Djokovic hitting backhands that you've cited:

http://www.youtube.com/watch?v=wlmhJTUFEfM

I believe I see a slight amount of elbow extension into that shot (I'm talking about Djokovic's left arm). Watch it and note whether his left arm straightens from the end of the takeback to hitting the ball. I believe he is marginally extending the elbow (straightening the arm) into the 2hbh. If anything, I believe he hits it with a straighter arm than he does with his fh.

Watching these videos, most 2hbh players have much less of a loop takeback on the bh-side as compared to the fh-side. Especially for players who hit a fh with a fairly straight arm (Nadal, Federer, Verdasco) the arm is bent more in the takeback and therefore there has to be straightening (elbow extension) prior to the shot. My interest in this extension is whether it is also helping some sort of reflex rather than just extending the arm straighter and perhaps allowing a greater arc on the swing and thereby easier pace and spin.

How long is a forward swing for a double handed backhand (in miliseconds)?

In the case of FOREHAND the corresponding number is below 250 miliseconds

[julian]

Does Nadal double handed backhand better that one of Djokovic?

If yes why?

[WildVolley]

Originally Posted by julian

Does Nadal double handed backhand better that one of Djokovic?

If yes why?

I'd argue that Djokovic has a better 2hbh than Nadal, but that's only from casual observation and I have no statistics to back it up, and I'm not sure the difference is simply a matter of form. I believe that Nadal tends to close the racket face more in the takeback than does Djokovic, or at least at the end of the takeback. Do you know of any sources with hard data on Djokovic and Nadal from match play? I think it is only a matter of time before we can get good computer data from something like shot-tracker that IBM used to provide at big tournaments.

Julian, I don't know about the length of the swing in milliseconds (doesn't that depend on how hard the person is swinging, or am I misinterpreting your question?). Are you getting these measurements from high speed video?

[julian]

Originally Posted by WildVolley

I'd argue that Djokovic has a better 2hbh than Nadal, but that's only from casual observation and I have no statistics to back it up, and I'm not sure the difference is simply a matter of form. I believe that Nadal tends to close the racket face more in the takeback than does Djokovic, or at least at the end of the takeback. Do you know of any sources with hard data on Djokovic and Nadal from match play? I think it is only a matter of time before we can get good computer data from something like shot-tracker that IBM used to provide at big tournaments.

Julian, I don't know about the length of the swing in milliseconds (doesn't that depend on how hard the person is swinging, or am I misinterpreting your question?). Are you getting these measurements from high speed video?

Is it possible to say anything about elbow extension of the RIGHT HAND of Nadal for his double handed backhand?

[WildVolley]

Originally Posted by julian

Is it possible to say anything about elbow extension of the RIGHT HAND of Nadal for his double handed backhand?

Here's a link to Nadal hitting some bhs that I'm looking at.

https://www.youtube.com/watch?v=j86FuSXtWUM

Watching that, it doesn't look as if Nadal's technique is radically different from Djokovic's. I still see more elbow flexion at the takeback stage with little or no 'pat-the-dog' and slight elbow extension into contact.

I think we can say a lot of the difference is that both Djokovic and Nadal have low take backs on the 2hbh and do not have the same sort of "pat-the-dog" motion into contact as on the fh-wing. But I'm seeing a lot of commonality in the two players' backhands.

[julian]

http://tennis.wettpoint.com/en/h2h/22080-91752.html
19-14 for Nadal

[julian]

Local experts say that a across double handed backhand of NADAL
is better than his DTL.
Julian wondering whether it is a correct statement
and why it is a correct statement

[WildVolley]

Originally Posted by julian

Local experts say that a across double handed backhand of NADAL
is better than his DTL.
Julian wondering whether it is a correct statement
and why it is a correct statement

I really don't know about that, but it may be possible to get data from someplace.

I'm not sure that the match data completely answers the question between the two players because Djokovic has improved his game considerably in the past couple of years and even a player who loses a match may be superior in a given stroke.

The thing that is more intriguing to me at the moment is the strong commonalities between the 2hbhs of Djokovic and Nadal. Can you specify a strong difference between the two players? I'm starting to see a lot of commonalities and fewer differences.

[BridgetJones]

Originally Posted by julian

I like
http://www.youtube.com/watch?v=wlmhJTUFEfM
I try to teach as close to this link as possible
I do NOT know whether it is a "big takeback"
I would say it is "compact" or "SMALLER".
I think it improves ssc
I will try to expand a bit later
PS Just to be specific:
I am talking about baseline stroke ONLY (no return of serve)
I am talking about DOUBLE HANDED BACKHAND ONLY

this is the backhand I want...(who doesn't)

Maybe not big takeback but he gets such a good turn maybe it seems that way? But I think perfectly timed and he can hit the ball early.

[BridgetJones]

Originally Posted by julian

Which level are we talking about?

If you mean my level, i have been playing since i was a little kid but I am still need tons of work. My backhand has always been reliable but I would not describe it as a weapon.

[julian]

Originally Posted by WildVolley

I really don't know about that, but it may be possible to get data from someplace.

I'm not sure that the match data completely answers the question between the two players because Djokovic has improved his game considerably in the past couple of years and even a player who loses a match may be superior in a given stroke.

The thing that is more intriguing to me at the moment is the strong commonalities between the 2hbhs of Djokovic and Nadal. Can you specify a strong difference between the two players? I'm starting to see a lot of commonalities and fewer differences.

Do you think grips at THE CONTACT are the same?

[WildVolley]

Originally Posted by julian

Do you think grips at THE CONTACT are the same?

They seem fairly close. I think that Nadal's right hand is slightly more of a standard semi-western than Djokovic's left hand. But it doesn't seem to be a large difference. I think Djokovic is holding almost an extreme eastern, but I can't see clearly enough (the resolution isn't high enough for me to tell).

Is that your impression of the grips? I think the other hand isn't as important as I think both hit an off-hand dominant stroke.

[julian]

How far away is a contact? (from a body)

[Power Player]

Originally Posted by julian

How far away is a contact? (from a body)

This is one of the money questions.

[WildVolley]

Originally Posted by julian

How far away is a contact? (from a body)

To estimate this well we would need some video shot either from directly behind or directly in front of the player and also to the side.

On the forehand side, for instance, Federer, Nadal, and Djokovic hit the ball away from the body more than players like Nishikori who keeps his elbow closer to his side. On the bh side, I think it is interesting to note that Djokovic keeps his left arm straighter at contact than he does his right arm at contact when hitting a fh. That might not mean the ball is any farther away, because the right hand limits the motion of the swing to some extent on the 2hbh.

When I have time I'll look for some videos with the angles we'd want for Nadal and Djokovic.

[julian]

A related question is:
is the bottom hand straight at THE CONTACT?
It would allow to calculate the distance

[julian]

Originally Posted by WildVolley

To estimate this well we would need some video shot either from directly behind or directly in front of the player and also to the side.

On the forehand side, for instance, Federer, Nadal, and Djokovic hit the ball away from the body more than players like Nishikori who keeps his elbow closer to his side. On the bh side, I think it is interesting to note that Djokovic keeps his left arm straighter at contact than he does his right arm at contact when hitting a fh. That might not mean the ball is any farther away, because the right hand limits the motion of the swing to some extent on the 2hbh.

When I have time I'll look for some videos with the angles we'd want for Nadal and Djokovic.

I have a shot from the REAR-the only problem is that it is on tennisplayer
Please do NOT angry at ME about it-just happened like that

[julian]

The one I saw are 500 fps
At some moment (very close to contact) the BOTTOM hand is straight.
It is a DIFFERENT model that SOME SHOTS by Agassi
It is complicated because:
on ONE HAND (pun attempted) one would like to have a hand straight
(after coming OUT of THE FLIP but very close to the CONTACT).
So we would like to employ SSC of biceps here
Some references related to SSC below
PS #1
J Appl Physiol. 1999 May;86(5):1445-57.
Length dependence of active force production in skeletal muscle.
Rassier DE, MacIntosh BR, Herzog W.
Source

Human Performance Laboratory, Faculty of Kinesiology, The University of Calgary, Calgary, Alberta, Canada T2N 1N4.
Abstract

The sliding filament and cross-bridge theories of muscle contraction provide discrete predictions of the tetanic force-length relationship of skeletal muscle that have been tested experimentally. The active force generated by a maximally activated single fiber (with sarcomere length control) is maximal when the filament overlap is optimized and is proportionally decreased when overlap is diminished. The force-length relationship is a static property of skeletal muscle and, therefore, it does not predict the consequences of dynamic contractions. Changes in sarcomere length during muscle contraction result in modulation of the active force that is not necessarily predicted by the cross-bridge theory. The results of in vivo studies of the force-length relationship suggest that muscles that operate on the ascending limb of the force-length relationship typically function in stretch-shortening cycle contractions, and muscles that operate on the descending limb typically function in shorten-stretch cycle contractions. The joint moments produced by a muscle depend on the moment arm and the sarcomere length of the muscle. Moment arm magnitude also affects the excursion (length change) of a muscle for a given change in joint angle, and the number of sarcomeres arranged in series within a muscle fiber determines the sarcomere length change associated with a given excursion.

PS #2
J Biomech. 2003 Sep;36(9):1309-16.
Stretch-induced, steady-state force enhancement in single skeletal muscle fibers exceeds the isometric force at optimum fiber length.
Rassier DE, Herzog W, Wakeling J, Syme DA.
Source

Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, 2500, University Dr. N.W Calgary, AB T2N 1N4, Calgary, Canada.
Abstract

Stretch-induced force enhancement has been observed in a variety of muscle preparations and on structural levels ranging from single fibers to in vivo human muscles. It is a well-accepted property of skeletal muscle. However, the mechanism causing force enhancement has not been elucidated, although the sarcomere-length non-uniformity theory has received wide support. The purpose of this paper was to re-investigate stretch-induced force enhancement in frog single fibers by testing specific hypotheses arising from the sarcomere-length non-uniformity theory. Single fibers dissected from frog tibialis anterior (TA) and lumbricals (n=12 and 22, respectively) were mounted in an experimental chamber with physiological Ringer's solution (pH=7.5) between a force transducer and a servomotor length controller. The tetantic force-length relationship was determined. Isometric reference forces were determined at optimum length (corresponding to the maximal, active, isometric force), and at the initial and final lengths of the stretch experiments. Stretch experiments were performed on the descending limb of the force-length relationship after maximal tetanic force was reached. Stretches of 2.5-10% (TA) and 5-15% lumbricals of fiber length were performed at 0.1-1.5 fiber lengths/s. The stretch-induced, steady-state, active isometric force was always equal or greater than the purely isometric force at the muscle length from which the stretch was initiated. Moreover, for stretches of 5% fiber length or greater, and initiated near the optimum length of the fiber, the stretch-enhanced active force always exceeded the maximal active isometric force at optimum length. Finally, we observed a stretch-induced enhancement of passive force. We conclude from these results that the sarcomere length non-uniformity theory alone cannot explain the observed force enhancement, and that part of the force enhancement is associated with a passive force that is substantially greater after active compared to passive muscle stretch.

[julian]

Originally Posted by WildVolley

To estimate this well we would need some video shot either from directly behind or directly in front of the player and also to the side.

On the forehand side, for instance, Federer, Nadal, and Djokovic hit the ball away from the body more than players like Nishikori who keeps his elbow closer to his side. On the bh side, I think it is interesting to note that Djokovic keeps his left arm straighter at contact than he does his right arm at contact when hitting a fh. That might not mean the ball is any farther away, because the right hand limits the motion of the swing to some extent on the 2hbh.

When I have time I'll look for some videos with the angles we'd want for Nadal and Djokovic.

Maybe it would be a good idea to specify videos you use
(probably via links)

[julian]

Originally Posted by Power Player

This is one of the money questions.

Do u have any specific suggestions?
Can I do anything specific to investigate?