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The Serve: Twist Versus Forward Rotation

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  • #46
    Originally posted by seano View Post
    My understanding with the elbow position in the upward swing, is to keep a constant angle between the elbow, shoulder and side of the trunk (shoulder abduction angle). I've heard the angle should remain constant at 100 - 110 degrees. Was asking Brian to see if that is true. When you start to tilt your body (lateral flexion) you are bring the contact point higher up and not to the side. A common mistake with the tip to "scratch your back" is it raises the elbow too high, leaving 2 problems. 1) less room to accelerate up 2) increase risk of injury (impingement of the shoulder).
    I just have trouble with this line of discourse as it doesn't seem to include the independent arm rise, the "adduction" that JY once talked about and is talking about again in his most recent promotion of TennisPlayer. Is there an independent sling of the upper arm or is there not? It can't be the same thing as the elbow rising and the racket tip going down and out to right. That wouldn't help the arm then to passively straighten. And if the javelin throw I'm trying to suggest does exist, it has to happen after elbow is lined up with the clavicle or shoulder balls or whatever, no (?), so what maximizes it (?). This is about both language and conception of the serve, no? I just think all of this has to be perfectly and precisely hammered out in someone's mind if he is going to progress. And in this case the someone is I.

    Am I wrong? Is there not a separate javelin throw where elbow, bent a lot or some, is the javelin? Should we be totally solid as elbow accelerates, and this is why the words "lift of the shoulder" and not "lift of the upper arm" were used? Semantics, semantics, I suppose, but terribly important, at least to me.

    I see a big consciousness change in the passive or motion-dependent arm straightening. I'm there and happy with this development in my serves. But the question is what's best to happen just before.
    Last edited by bottle; 10-14-2018, 06:12 AM.

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    • #47
      I watched the video again. I know it's all about sequence, but when one watches, one may see, or think one sees, as I just did, the fast independent elevation of the elbow coming neither before nor after the lowered racket tip moving out to the right but just then. In conjunction with all kinds of energy starting in the lower body. Am looking forward to this change. And may have gotten carried away with the javelin image.

      But something like that can happen when you leave the text of a complicated blueprint and start implementing all on your own-- which you have to do, it seems to me, I can't see any other choice. Unless one wants to live forever in a blueprint.

      That said, it could be helpful to study the blueprint, implement like mad, return to blueprint, implement again, etc., etc., back and forth until the outcome is great. One thing for sure: This blueprint is great and a person ought to try to carry it out as best he or she can.
      Last edited by bottle; 10-13-2018, 10:47 AM.

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      • #48
        Take Me Seriously, Please, Anybody, You're All Good

        Turn off the sound and go to 1:14 of the video. Play that sequence of Federer's upward rotations over and over. Just get on 1:14 and click click click again and again.

        This ought to resolve the questions just brought up. Ought to but won't. Some question still will remain: Is there independent raising of the elbow or not?

        Note that left elbow appears to go down at the exact same rate that right elbow goes up.

        Does that argue for no independence of elbow? Or for matching independence of BOTH elbows?

        To implement what is best for oneself there can be absolutely no doubt at all?

        A few more of same click from 1:14 . Now I think the left elbow goes down faster than the right elbow goes up.
        Last edited by bottle; 10-13-2018, 03:22 PM.

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        • #49
          Originally posted by seano View Post
          Brian - I have several questions about the latest serve video (Rotations in Upward Swing).

          1) Is it a correct assumption that the synchronization of the lower and upper body is that the leg drive initiates the racquet drop?
          2) The racquet to the outside in the external shoulder rotation portion (racquet lined up with the elbow exiting the backswing and entering the upward swing), is that a technique issue or a flexibility issue?
          3) 2 parts - a) When raising the elbow in the upward swing, is that the beginning of the somersault motion and lateral tilt of the trunk?
          b) When raising the elbow, does the shoulder abduction angle remains constant thru out (100 - 110 degrees?)?
          4) The wrist flexion you mentioned after internal shoulder rotation, is that to bring the wrist to a "neutral position"? I know you are only talking about the upward swing that takes place before contact.You're not suggesting to flex the wrist further than that, correct?
          5) What are your thoughts on the serve tip - "to achieve greater external rotation of the hitting shoulder, in "full racquet drop" try to keep the elbow higher then the hand".

          Thanks again for your input.
          1- That is one of 3 roles of the leg drive - think I will cover that coming up.
          2- Both
          3- See separate post.
          4- yes, flexion to neutral.
          5- seems feasible.

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          • #50
            Most of the discussion seems to relate to the independent shoulder motion relative to the trunk. Keep in mind that in the upward swing the cartwheel has been completed and the main torso rotation has changed to twist about a laterally tilted torso axis. The cartwheel's main role is to transfer forward angular momentum (rotation) toward the arm during the backswing.

            In the upward swing there is independent rotation of the arm at the shoulder in for lack of a better term abduction/adduction (anatomically hard to describe). That motion along with twisting of the torso (derived from the forward rotation) account for most of the racquet head speed in the first third of the upward swing. These contribute in about equal proportion, roughly 40% each (Gordon and Dapena, Journal of Sports Sciences, 2006).

            In general, the positioning of the elbow from independent non-twisting rotation of the shoulder will not (and should not) violate the 100 degree rule due to the afore mentioned lateral tilt of the torso axis.

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            • #51
              Thanks.

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              • #52
                Thank you Brian

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                • #53
                  I have watched your videos on the serve and have read your articles. Very good information I understand the leg drive and hip driving up and angular causes the racquet drop.I am concerned about the trunk rotation for young players during growth spurts. Will it not cause back problems?
                  also is there pronation or does the wrist go to a neutral position from the rotation of the upper arm from the upper swing through contact. isn't it similar to a quarter back passing a football?

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                  • #54
                    From what I've read - The lateral tilt has been known to create problems in the lumbar region if focused on at too early of an age, better to focus on after puberty. I like the following phrase - ''coaches must address different mechanical features at various phases of the developmental pathway. Specifically, preparing the body segments can be taught from a young age, however the propulsive movements do not begin to mature until after the onset of puberty".
                    Last edited by seano; 10-15-2018, 06:12 PM.

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                    • #55
                      jmtennis - great questions - thanks.

                      There is of course some risk associated with trunk rotation but it is my experience it is no greater than the risk associated with playing tennis in general, or any sport for that matter. Most of back injuries seem to occur through a simultaneous combination of twisting and non-twisting torso rotations. The most dangerous is twist combined with extension often seen in preparation for the backswing.

                      I've been fortunate not to have any back injuries in my many years of coaching. I'd like to believe this is due to good mechanics but maybe I'm just lucky. The lateral trunk rotation occurs before the twisting - they do not occur with significance at the same time (lateral - backswing; twist - upward swing). Further, the extent of lateral rotation is built in over time starting at about 5 degrees and progressing to about 25 degrees. Even 25 degrees is pretty moderate and fortunately the most required to transfer forward angular momentum.

                      Pronation of the forearm is insignificant - the forearm acts as transmission for the internal shoulder rotation but is not independently pronated, in fact the opposite, research has indicated it is supinated slightly on average. The wrist goes to a neutral position from muscular contraction of the wrist flexors - this is not a motion dependent event - internal shoulder rotation tends to drive the wrist into extension, not flexion.

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                      • #56
                        Twist Rotation Versus Forward Rotation…Dr. Brian Gordon


                        Transcribed from the video below:

                        https://www.tennisplayer.net/members...ersus_forward/

                        Having played a wide variety of sports it quickly became apparent to me that tennis was by fare the most complex and difficult to master. So I can remember as a young man…actually a boy growing up I spent countless hours thinking about how this stroke should work, experimenting with the best way to do things which is a little bit unusual for a child of that age. But if I was to be completely honest I would say that most of the concepts that are in my current teaching methodology have been present in my recent research were actually hatched before I was twelve years old.

                        So I guess it was inevitable at some point that I would further my knowledge and course of study become involved in the study of biomechanics which is the physics of human motion. Because of my interest in tennis strokes as a young man and trying to become a better player that was obviously what I chose to work on. All of the strokes are of interest to me but of particular interest was the serve because it struck me as being one of the most complicated and interesting motions in all of sports.

                        So as my education progressed and I became able to use quantitative methods of measurement and take a much deeper look at stroke mechanics in the serve in particular several things appeared to emerge. The information that came out through my study starting in essentially 1995 through my Masters and PhD work and up to the present in my applied work on the tennis court, showed that the certain mechanics that I was seeing are much different than the ones that I was taught when I was a young man.

                        In particular what I was taught when I was young and to a great extent this is still prevalent in tennis today is that the serve is fundamentally a twist based motion. Which is to say that the forces that are exerted on the ground in the preparation of the body should be such that the body is rotated very far away from parallel to the baseline…er, perpendicular to the baseline and that the forces that are exerted on the ground are used to generate a twisting rotation of the torso. I can remember as young as eight years old when I was told this, thinking this makes absolutely no sense.

                        Why would a motion in which I am fundamentally developing racquet speed in a vertical direction be predicated by a twisting rotation of the torso? So, in other words, I am being asked to twist my body this way and yet produce racquet head acceleration this way. From a very young age that made absolutely no sense to me. What was interesting is that as my knowledge increased and more data come about, I found out that the more better servers in more recent times do not in fact use a twist rotation of the body directly to impact racquet speed development.

                        To be clear, when I talk about a twist rotation, I am talking about rotation of the body around an axis that is vertical. So my hips, my shoulders, everything is twisting this direction about this axis which means that I am using ground forces, pushing on the ground interacting with the ground to generate a twisting rotation. But what the research has shown is that the way that the serve is developed is not so much through this twist rotation but actually through a forward rotation of the body. A forward rotation of the body, which I refer to a lot as a somersault rotation, is around an axis that is parallel to the baseline. If we consider that axis passing through the centre of my body, I would be generating rotation starting from the ground and then through transferring the rotations around this axis. A forward axis making my body rotate essentially forward which is in stark contrast to a twisting rotation.

                        So all of the actions that I use starting with the ground, pushing on the ground are used to develop a forward rotation and the subsequent body rotations are used to transfer that rotation or what in biomechanics we call angular momentum through the torso and into the hitting arm. This is a far different paradigm that I learned as a boy and a paradigm that is still fairly prevalent in tennis. So in a twisting rotation I would start rotating away from the baseline, I would use the ground to generate a twist rotation and I was actually taught to step through with the back foot. Again that makes no sense if the goal is to generate vertical racquet acceleration.

                        More recent serving and what my serve evolved to without coaching, by the way, is that rather than doing that you generate forces from the ground to generate a forward rotation you would leave the ground and land with the front foot with the body actually tumbling forward. So in other words I am developing all of this rotation and using that as kinetic fuel for the motions of the arm approaching impact in the upwards swing. I don’t mean to imply that the twist is not actually important. What I am saying and what I will discuss later is that the twist rotation of the body does not necessarily need to be generated by exerting effort in pushing against the ground. The twist rotation, particularly of the upper torso, can be derived from the forward rotation generated from the ground by placing the body in a very particular orientation in the air. That seems to be what most of the high level servers do to this day.

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                        • #57
                          Twist Rotation Versus Forward Rotation…Dr. Brian Gordon (cont.)


                          Transcribed from video below (cont.)

                          https://www.tennisplayer.net/members...ersus_forward/

                          I will also say that there is a requirement for a slight twist rotation from the ground reaction so in the ground reaction again I am trying to generate a forward rotation of the body. I do need a minimal input from the back leg to get the hip initially started around. That will help as I acquire twist rotation from the forward angular momentum later in the swing.

                          When I talk about these things people inevitably say to me…”oh, but there are examples in the fairly recent history of players that do seem to still be rotated like this”. So in other words they appear to still be driving a significant amount of their kinetic fuel from generating a twist rotation from the ground. But closer inspection of those players shows that they actually use this forward rotation or somersault based swing mechanics and they are only essentially starting from a more turned position in order to change the axis of rotation from parallel to the baseline to a little bit skewed. The reason that one would want to do that is that it makes the rotation generation a little bit more diagonal compared to the baseline which is a very useful thing in generating spin rotation on the ball, particularly on kick rotation.

                          So…for servers, Pete Sampras being a notable example, that generated both pace abut also significant amount of rotation on the serve, it would be beneficial to instead of having a purely forward rotation axis to have one that is diagonally skewed to diagonalize the transition from the torso rotation to the arm and having the arm segments coming out not so much forward as they would on a flat power serve in the forward oriented one to a more diagonal path which would facilitate their ability to generate a significant amount of rotation on top of the (power/path ?).

                          This series is really a follow up to a series that I wrote on John’s site tennisplayer.net in the mid 2000’s. It was a very detailed and difficult to understand and read series of five or six articles really getting into the base mechanics of the stroke. This is a follow up in that it is designed to be a little bit more applied. In other words, I am describing things rather than writing them in brutal detail. So…hopefully that will enhance understanding of what I wrote a little over a decade ago. Most of which still stands…actually all of it still stands. There’s been some additions to it.

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                          • #58
                            Interesting video Brian. I can call you Brian...can't I? Do you know in Sweden that people never refer to doctors and Dr. So and So? In this society they are really on guard that nobody thinks that they are better anyone else. Just a little cultural anomaly.

                            Brian...did you ever read my little story of the roller coaster serve? I'm not certain if I drew it to your attention or not. I transcribed your video in the two posts above. It's a great exercise for me. I must have heard the video at least five times in total by going back and forth...listening and typing. I think it really enhanced my understanding of what you were driving at.

                            Question for you Sir...do you know anything about golf and the golf swing? I think that you would find that motion to be ultimately fascinating too. I have compared it to an upside down tennis serve. In a tennis serve we attempt to tee the ball up where we are going to hit it instead of teeing it on the ground. Golf swing analysis seems to be light years ahead of tennis swing analysis. You seem to have a corner on the market when it comes to breaking down the motion to its bio-mechanical foundation.

                            I find this concept of "ground force" rather curious. I notice one of your models using a platform stance which a advocate almost exclusively. The less moving parts, the less that can possibly go wrong. In such a complex motion it seems wise to make it a simple as possible. I saw on a golf video the instructor was recommending to use the feet like they were turning a screw into the ground on the backswing and doing the reverse on the forward swing.

                            Very interesting video and it was fun to transcribe it. Studying your paradigm and at the same time studying you. Nice delivery! Nice serve!

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                            • #59
                              Thanks for this don_budge. To me it looks better in black and white than watching an old guy gimping around.

                              Never thought much about the Dr. thing. I guess on some level it validates the 20 years of "higher education" to understand human motion. On the other hand it probably makes many wonder who would be crazy enough to spend that kind of effort to understand how to hit a little yellow ball. At any rate, please call me Brian - no-one I know calls me Dr. and most call me Bri - my players shorten it to B.

                              I didn't read your piece but will if you tell me where to find it. Afraid golf mechanics is outside my realm although some in my academic labs studied it. From that I got bits and pieces. I will say the best qualitative description I've seen of mechanics in any sport is the golf book: Search for the perfect swing by Cochran and Stobbs. Are you familiar with it?

                              I'm with you on the platform stance. Thanks for your kind words and time, BG
                              Last edited by BrianGordon; 12-03-2018, 06:56 PM.

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                              • #60
                                Originally posted by BrianGordon View Post
                                Thanks for this don_budge. To me it looks better in black and white than watching an old guy gimping around.

                                Never thought much about the Dr. thing. I guess on some level it validates the 20 years of "higher education" to understand human motion. On the other hand it probably makes many wonder who would be crazy enough to spend that kind of effort to understand how to hit a little yellow ball. At any rate, please call me Brian - no-one I know calls me Dr. and most call me Bri - my players shorten it to B.

                                I didn't read your piece but will if you tell me where to find it. Afraid golf mechanics is outside my realm although some in my academic labs studied it. From that I got bits and pieces. I will say the best qualitative description I've seen of mechanics in any sport is the golf book: Search for the perfect swing by Cochran and Stobbs. Are you familiar with it?

                                I'm with you on the platform stance. Thanks for your kind words and time, BG
                                I think that transcript is a good complement to the video. I thought you were looking pretty distinguished and sounding very credible. A nice performance. I'll check out the golf book. You may have missed your calling. It seems to me that what you are doing for tennis is what any number of fellows are doing for golf. I really feel that generally speaking there is a much better understanding biomechanically speaking in golf than there is in tennis. There aren't too many doing the sophisticated analysis that you have laid out from your research.

                                I sometimes cryptically make the comment that I have learned more about teaching tennis from playing, studying and teaching golf than I did from playing tennis. I describe tennis as golf on the run. The nice thing about golf is that you don't have to succumb to the years as early as you do in tennis. There isn't any real hurry to get to the ball. Which is another story in itself. It would be interesting to see if your understanding of biomechanics would help you to learn the golf swing.

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