Serving wrist flick?

Discussion in 'Tennis Tips/Instruction' started by tiochaota, Aug 19, 2010.

  1. Recon

    Recon Semi-Pro

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    Seems like me and you are battling many. Ridiculous, these guys actually believe novak and top pros don't know what their doing, and are basically retarded. Good point on most coaches were high level players, Here is what I don't understand. these guys are learning from pro strokes (analyzing video, breaking down key movements, giving them fancy names, etc etc) but wont listen to the very people they're trying to learn from...How STUPID does that sound?
     
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  2. Kevo

    Kevo Hall of Fame

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    First, people have no idea consciously about most of the stuff their body does. Do you teach a baby which muscles to activate in order to walk? As a coach, I try to teach only what I need to. I've seen plenty of students put off and confused by too much instruction. I have recently started using my cell phone camera to show some of my students what they look like on court. They hardly ever look like what they think they look like.

    So I don't think it has anything at all to do with intelligence. People just aren't wired to be conscious of all that is happening with their bodies. In fact it's the opposite. Imagine if your brain made you consciously aware of every nerve that fired all the time. Wearing clothes would require some sort of meditation to try and block out all the sensory information coming in.

    So while Djokovic's brain clearly knows how to hit a serve, we can't necessarily conclude that he is consciously in control of that knowledge.

    The snap being a significant source of power is certainly true assuming you define snap appropriately. I've looked at the Elliot study enough to know that there are caveats to the work. Certain things were excluded from study. The 40% figure was hand/ulnar flexion. That is not the snap that most people refer to when they say snap.

    I don't think anyone is arguing that the wrist isn't used at all. My take is that people are arguing that it's not used in the way most people think of when they say snap.
     
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  3. chico9166

    chico9166 Guest

    Really not trying to sound elitist Guy Glinch. :)

    As per your points.

    1)Well, I am both, a former major college player, and tennis instructor for the past 20 years, and certainly don't think I have the market cornered on absolute truth. I have seen great players who were terrible teachers and poor players(by industry standards) who were fantastic teachers. It really gets down to the individual pro, and how they go about there job. Like any other profession.

    2)Haven't seen that piece by Heath, but have read much of his work, and think he brings alot to the table as far as instruction goes. I actually think he's great. Just probably wouldn't agree with him on this one. I tend to take a more macro approach with students. The loading and storing of energy, fluidity, and priming the muscles in a more motion dependent way. The upper arm, forearm and wrist will "fire" for the most part, if set up properly. So no, I wouldn't focus on pronation, flexion, or any other muscular movement, at the end of a kinetic chain. Just my opinion.

    3)Disagree here. Just because a player can do something well, doesn't mean they can articulate it, or teach it well. Or even understand it well, for that matter. This really is common knowledge. I'd rather take piano lessons from a trained professional teacher, than from Mozart, who could "just play by ear". Dennis Rodman was a great defender, but I'll take Bobby Knight any day if I want to really understand that end of the court.
     
    Last edited by a moderator: Aug 21, 2010
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  4. JohnYandell

    JohnYandell Hall of Fame

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    Funny thing about Novak because he and his coach sought my advice about his serve and studied high speed video I gave them. As you may have noticed he tried some changes and then mostly abandoned them. I was able to give these guys film of all the variations.

    The wrong assumption here I believe is that this is an either or answer--either you have to take Novak literally at his word, or, take mine. Respectful collaboration is the way to go. I always learn something from talking to tour players and coaches, and they ususally tell me the same.

    Words like "snap" are funny things. And I have moderated or expanded my view on that somewhat over the years. We are doing new high speed video right now in Cincy and you can see on many serves that there is ulnar deviation right after contact--that flex of the wrist slightly to the right. Want to call that snap fine.

    The wrist definitely moves from a laid back position at the drop to netural at the contact. Want to call that snap, go for it.

    But if you look at Novak or any pro what is clear is that the wrist doesn't break forward during or even right after contact. That was always my big point.

    The upward motion is predominantly the elbow extension and the massive rotation of the hand and arm. Want to call that snap? Fine with me.

    But what the tennis channel snap guys calls a snap--that 90 degree break forward--doesn't really happen and in fact if you try to do it, you'll impede that critical rotation move.
     
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  5. JohnYandell

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    And one more thought about what tour pros "know." My experience has been that they often do not process technical information verbally.

    A friend of mine who grew up with Sampras had him at a clinic for some juniors and said something like "Pete, explain to us how you hit your volley." Pete's face turned white and he said "I don't really know how I hit my volley."

    In my opinion Pete and others are processing physically and visually. When I did my first instructional video in the 1980s with J Mac, he had to do some simple drills to demonstrate the basic strokes. Knew he needed to do it, did it, didn't like it at all, because he said it made him start "thinking" about his strokes. Quote: "I am a no brain player."

    But later in the shoot he told me. "Sometimes before I hit a shot I see it flash across my mind." Another time he described it as "a feeling that has a picture." That's the only way it'll work in actual play in my opinion. As Bill Russell said: words and movement don't mix.

    Now other players are more cerebral and off the court can go back and forth between the body and words.

    But my experience is that a lot of players forced to use words can't articulate what they do, or articulate something different than what the video shows they do.
     
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  6. tiochaota

    tiochaota Semi-Pro

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    So my wrist should not move at all during the serve? Just let my arm do the serving?
     
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  7. JohnYandell

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    You need to match the positions of good servers at the key points. A great racket drop and then the complex upswing that resembles giving the ball a high five with a continental grip. If you are relaxed, most likely the wrist will take care of itself.
     
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  8. tiochaota

    tiochaota Semi-Pro

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    If I'm relax how would my serve have any power at all? I should not muscle at all? Just swing through relaxed?
     
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  9. Vyse

    Vyse Semi-Pro

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    Yes all relaxed, it will be 20x times better. Think about hitting the ball with the edge of your racket like a hammer but dont tense your arm at all. Its like a spaghetti noodle.
     
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  10. JohnYandell

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    It's like throwing a ball--most like a football. A balance of contraction and relaxation. That's one of the challenges to make the positions which obviously requires muscle contraction, without tightening up more than is necessary which slows everything down. Honestly it is mostly just a matter of making the right technical positions--which most people don't.
     
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  11. GuyClinch

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    Here is the problem - this is actually to be expected even if the motion involves alot of wrist. This does not help or support your argument at all. If anything it supports the opposite view - that the wrist is used in the shot. A great example - and the guy who wrote the revolutionary tennis website brought this to my attention (I am not saying its my idea) - is a basketball jumpshot. Now if you snap a picture of a guy shooting a jumper just at it leaves his hands the wrist is still laid back or neutral. But of course we all know that just a few milliseconds later the wrist ends in a full forward position.

    This is precisely the argument you use to "prove" the wrist isn't a factor and it's just doesn't pass the sniff test for me.

    Catch a guy with the ball just leaving his hands - and you know what his hand is in a neutral position or laid back.

    http://img513.imageshack.us/img513/5697/shothk5.jpg

    So how can you claim that your 'analysis' is proof the wrist isn't being actively used - especially when high level servers claim they do this. And when EMG indicates alot of hand flexion? Your making the bold controversial claim - so the onus is on you to provide evidence. Call me boring but I believe most pro athletes know what they are doing if they claim they do. The ones that may have "no idea" (not Novak) maybe they wouldn't make good teaching pros.
     
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  12. GuyClinch

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    I get your point but I think this is a gross exaggeration. First of all tennis serves are not learned at birth or in early childhood
    Yes we have little idea of what exact muscles are used in breathing and our conscious mind might not know how to breath or how our heart beats. But this is not a tennis serve. A tennis serve is something learned and taught.

    Your argument carried to its logical conclusion leads to alot of absurdity. We shouldn't ask carpenters how to hammer a nail because they don't know what their body does. We shouldn't ask Bode Miller how to ski, we shouldn't ask race car drivers how to increase our lap time etc etc.

    Like I said its rather a ridiculous elitist argument. If Novak said "well I have no idea how to hit a serve but maybe you use your wrist" then you would have a point.

    Actually what makes elite athletes like Novak so good is that unlike the people you will have in your class he is a very talented. In that like other pros he can simply watch other pros play and expertly mimic their motions. Pro athletes have far superior body control and body awareness.

    The root of the problem here is your not giving pro athletes enough credit. You think again they are too stupid to know what their body is doing. And yes I do think this is a kind of intelligence. It's just not measured by IQ tests.

    But it's actually the exact opposite. Pro athletes have better body control. I'd much rather get a tennis lesson from Justine Henin then a "book smart' pro who attempts to teach from a tennis book.

    I saw Henin explain her backhand on the tennis channel - and I was able to go out and add spin to my backhand using her tips. She is aware of what really works on the court and like other good athletes aware of her body.

    I see no reason to doubt Novak - and alot of reasons to doubt a theory based on in my view flimsy film evidence. But like I said before that's just my opinion. Its an opinion shared by many though even teaching pros.

    So again the book is not closed on the wrist and the serve. I think Yandell was just looking for an interesting counterintutive finding and ignore what's really there in front of your face. The serve is a shot that involves the wrist - and specifically hand flexion to the tune of 30% of your power. That's why you can stand at the baseline and serve with just a wrist motion.

    Blake says he can whip it in there at over 100mph. That might be an exaggeration (as he probably cheats and uses some shoulder rotation or something).. But I think its likely he and Novak are correct.
     
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  13. GuyClinch

    GuyClinch Hall of Fame

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    It's funny you say this - because it actually goes against your theories on the wrist use. Pat Dougherty (a respected serve expert) compares it to a pitching motion but in a upward direction.

    Here is a tidbit I found about pitching:

    I will give you some credit. My feeling is that almost alone you managed to steer thousands of teachers in a direction that I don't believe is supported by the evidence. I imagine I could find much the same information about a football throw which for me involves even more wrist action then a baseball pitch.

    Wrist FLEXION - which I think is equivalent to the hand flexion that Bruce Elliot indicates is responsible for 30% of the serve power.

    Seeing that I am not some expert I can't say you are wrong but I sure don't find your argument convincing at all. This is purely an academic argument. I will concede that for many students you probably don't even have to teach the wrist flick. But its helpful for some.. I find I can bring the ball in sooner and with more power if I start to think about emphasizing it.

    I actually learned to do this from my coaching on overheads. If I missed it long my coach would always say 'snap the wrist" and I did - and my overheads were fixed.
     
    Last edited: Aug 22, 2010
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  14. JohnYandell

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    Guy,

    I don't think you have understood what I have said.

    The point I am making involves the forward break in the wrist. If you think I am arguing that there is no wrist movement in the serve, that is not what I wrote in the post.

    I am not going to get into or respond to the insults and personal attacks that have characterized some of the exchanges on this thread. There is no justification for taking a rude and hostile tone.

    But I think what I have said is clear and is supported overhwelming by the video evidence, which is found not only in my articles, but all over the internet.

    You can also see what I am talking about here, in a clip I posted a while back on TW:

    http://www.tennisplayer.net/public/tw/nadal/hs

    Watch the hand and arm rotation. Every top player looks the same, and the amount or rotation is a matter of degree. The guys who advocate the forward snap through the contact end up with the racket face pointing downward at the court, rather than at the side of the court.
     
    Last edited: Aug 23, 2010
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  15. FloridaAG

    FloridaAG Professional

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    My wife once asked Roddick for serving advice, and his response was I don't know I toss it and swing as hard as I can.
     
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  16. GuyClinch

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    I have made no insults - nor have I used any rude or hostile tone.

    I understand that challenging someone's work can be upsetting. But I am challenging your argument (in this VERY specific area) not you the person.

    Do you not agree with this statement? I am arguing that the wrist is conciously involved in strokes and the wrist muscles are actively firing to provide additional power in tennis strokes and in this case the serve specifically. Though its also used in the forehand and OHBH IMHO.

    Its a pretty simple argument - its a yes or no thing. I am arguing that your famous "the wrist is myth" article is if not wholly incorrect based on shaky and unsupported evidence.

    So yes of course the wrist moves. That's not the issue. The issue is the body firing those wrist muscles to aid in serve accuracy, power or spin.

    I say yes it is - and studies back up this theory. Novak says it is - and I believe him.

    Pete
     
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  17. GuyClinch

    GuyClinch Hall of Fame

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    Maybe Roddick isn't as nice as Novak and didn't want to tutor your wife. <g> Can you imagine how often Roddick gets that question?! Poor guy..
     
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  18. FloridaAG

    FloridaAG Professional

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    He was about 19 years old or so when this happened and he was chatting with everyone at an event and was happy to answer the question. Could he be dodging the question of course - it was an anecdote.

    I would think if Novak really understood the serve he would be able to fix his serving problems
     
    Last edited: Aug 23, 2010
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  19. GuyClinch

    GuyClinch Hall of Fame

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    I get what your saying - and I think this happens to a point. I Let me give you an example..

    My dad drives a stick shift in his car. This is learned process - now if you ask him what he does - he will say he just shifts or he just drives.

    Once you have driven a stick for a while you don't have to think about it. It's "automatic" for him - I am sure its quite the same with serving or dancing etc.

    This doesn't mean though if he stops and thinks about it for a second he wouldn't be a great person to teach someone how to drive a stick shift. He would just have to kind of 'rewind" a bit and say let me see I hit the clutch like so and add some gas when I want to down shift etc etc.

    Who would you go to to learn a stick? Someone who drives a stick shift. Likewise - who knows how to hit really big pro style serves. Novak. Just because he thought about it a bit and explained how he does it - and some athletes have not.

    That doesn't give people some blanket excuse to think that no athlete knows what he is doing. That's just a ridiculous elitist argument. I wouldn't go take dance lessons and tell my instructor - oh you don't REALLY know what you are doing.. Would you? And yes most dance instructors are great dancers. Just like most teaching pros are very good players (and sometimes former greats).

    In this particular case though I still bet that Roddick was just dodging the question.

    I imagine he gets it all the time AND has seen TONS of video about his own serve so he is fully versed on how to hit huge serves. These modern athletes are quite high tech and often versed in the science of their game too. I'd bet money that Tiger Woods could teach more on the golf swing then most any teaching pro I could find around where I live..

    Heck doesn't Federer go without a coach? Don't try telling me he doesn't know how he hits his forehand. When he credits his fast wrists I believe him.

    Pete
     
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  20. JohnYandell

    JohnYandell Hall of Fame

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    Let's just say I disagree about the tone and nature of your comments.

    But those are your choices to make. My stance has always been that it's about the positions in the motion. And that was the stance I took in the original article.

    That the wrist doesn't break forward.

    I am going to assume that we agree on that as you did not respond to or challenge the clip. You want me to respond to a specific question, which I think is an interesting one, which I will if we are now in agreement about the actual shape of the motion.
     
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  21. pug

    pug Semi-Pro

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    Dave, John, and anyone else,

    Ok, so how is this accomplished? Does anyone have a video of this?

    I can not hit 100 MPH in a full serve motion, how can some do it from seated/kneeling position? Pronation, wrist-snap, or what?

    Thanks.
     
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  22. spacediver

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    in terms of consensus here, it seems that just about everyone here, John included, agrees that a degree of wrist flexion occurs before contact with the ball during the serve. Nobody seems to be caught up on the idea that the wrist flexes past a neutral position before contact. I believe this is what John means when he talks about no forward break in the wrist.

    GuyClinch is advocating the idea that there is conscious control of this wrist flexion.

    John isn't denying this, but is saying that it is perhaps not pedagogically useful to emphasize conscious control of this flexion.

    Now to aid discussion, we could perhaps lump all wrist action (deviation and flexion) into one term, and call it "wrist action". I am ignoring pronation for the time being since that doesn't actually involve a change in the configuration of the wrist joint, but rather the shoulder and elbow joints.

    So, given that we all seem to agree that wrist action does indeed occur, let us turn to the question of whether innervation of the motor neurons that control wrist action is necessary, and whether it is pedagogically useful to emphasize such motor control.

    My understanding of the whip like action involved in a kinetic chain is as following:

    Conservation of angular momentum dictates that if the previous link reduces its velocity (or comes to a complete stop), the momentum is channeled into the next link. Given the architecture of the human body, the next link is almost always lighter. This means that if all the momentum is channeled to each successive lighter link, then that next link will travel at a higher velocity.

    So it is possible to achieve whip like action without imparting extra energy to the successive links.

    This, however, does not mean that extra energy cannot piggy back ontop of this natural whip effect.

    In fact, my own personal experience suggests that my most effective whip actions are when I feel that stretch of the muscle, and can feel the momentum starting to drive the motion by itself, and then i fire ONTOP of that for a turbo boost. It's all about timing.

    So intuitively (and this is solely based on my own intuition), it appears that independent innervation of the wrist could indeed enhance racquet head speed.

    Whether it is useful to emphasize such independent innervation is an empirical question (and a tricky one to approach). Such independent innervation may happen naturally once a student gets a good feel of the motion and learns to fire at the right time.
     
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  23. JohnYandell

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    Great summary space.

    Not sure that we are all agreed on the lack of forward flex after the contact--but it would be hard to argue that it happens. You can find plenty of high performance serves where the wrist stays neutral all the way through the followthrough, or breaks minimally.

    In all cases, even when there is forward flex in the followthrough, the wrist stays in the netural position for a clear interval from the contact out through maximum rotation, showing that the motion is not continuous. In the Rafa clip that takes about 1/10 of a second. That's the same interval as the movement from the drop to the contact, where the wrist is flexing up to the neutral position. Now it stays still for the same duration and that's continuous? Nope.

    If that's not enough evidence, then try emulating the position in the Rafa clip at maximum rotation and then flex the wrist forward and see if you think movement past neutral could have anything to do with the hit.

    In the original article, that's all I really claimed. When Brian Gordon started writing for Tennisplayer, he introduced the concept of motion dependent torques to explain the wrist action. The idea being that the forces in the upward swing of elbow extension and arm rotation drove the wrist motion.

    At about the same time I had some correspondence from the Australian physicist Rod Cross who said the same thing. He calculated that trying create the wrist flexion on the way to contact would actually slow the racket down, because the rotational forces were so much greater than anything you could generate with a conscious forward flexing motion.

    The way he put it was this: rather than the wrist snapping the racket, the racket was snapping the wrist.

    That made sense to me from my experience and that was where the addendum came from, that the wrist was a hinge and passive.

    I would like to see the actual reference to the studies on muscle measurement that Guy refers to, that would be interesting.

    There are three issues here: what happens--the actual motion.
    How it happens--what muscles do what. And making it happen--trying to snap, visualize positions etc. I can refer to Brian or Rod on the how, but my expertise is in the what, and to a lesser but not insignificant extent, the making.

    I've lived long enough to see that how people produce tennis motions and what keys and words they use may not corelate with reality. Don't think that matters. In fact it's a positive if it gets the correct result in terms of the actual motion. That is how I see this vague term snap. Works for some. But emphasizing it to the point that it produces an obviously inferior motion is the problem.
     
    Last edited: Aug 23, 2010
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  24. CoachingMastery

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    It is accomplished by optimizing the rhythm and technique available. It isn't just pronation, but a combination of a fluid motion with the speed of the racquet reaching peak acceleration at the contact point. (Obviously, something all players who are looking to serve with as much velocity as possible will be striving for!)

    Most players who can't serve over 100 mph usually can be seen swinging way to much with the arm, usually using the wrong grip, (usually the eastern forehand grip), and using an inadequate service motion including limited collapse of the racquet arm, dropping or pulling down the hitting elbow, opening up too early, etc.

    I can't pinpoint your own particulars of why your not able to reach your serve goals, but look at these issues mentioned and compare your strokes to the pros and I think you will see the differences.

    I compare it to golf: I also taught golf for many years in Phoenix and had a girls golf team. I drive close to 300 yards and was hitting my second shot ahead of our #1 girls group...Grace Park who was playing on our opponents team, hit her drive past mine from the same tee box as mine, as I watched her shot roll past me. Grace was only about 4'9" tall but could out drive me and most of the good players I usually played with.

    This also explains why some of the women on tour serve nearly as hard as some of the men.

    Unfortunately, I no longer have video clips of me hitting the 100+ mark from my knees but it isn't that uncommon among skilled teaching pros to show this from time to time.
     
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  25. Kevo

    Kevo Hall of Fame

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    I commented on this earlier in the thread, but the study give the 30% value to palm/ulnar flexion. This, from what I can tell with my limited biomechanics knowledge, is the hammering type motion not the flappy hand wave motion you see many players use when they serve with a forehand grip.

    Anyway, I think your doing a great job with your video analysis John. Thanks for posting and contributing.
     
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  26. bhupaes

    bhupaes Professional

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    ^ I agree with John's analysis, too. But I am really curious about how analysts determine how much each segment contributes to serve speed. It has to be a very inexact science, any way one looks at it. Are these motions studied in isolation? If I use my whole service motion, I can thump the ball on to the back fence. If I just use ulnar flexion, it is, well... pathetic. If I stand still, hold my wrist fixed, and use my upper arm, again... it is pitiful. The whole is simply much more than the sum of the parts. What does one do to determine that the hand motion contributes 30% and the arm motion contributes 40%, and the legs only yield 15%? :confused:
     
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  27. tiochaota

    tiochaota Semi-Pro

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    So I DON'T use my wrist at all?!?!?! darn this is complicated...
     
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  28. pug

    pug Semi-Pro

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    Dave,

    Thank you for your reply. Yes, sadly, I know there are vast differences between what I do and what an accomplished player does in regard to the service motion. I fear that it may be a case of, "You can't get there from here," where I can not self diagnose my issues and don't have the means for professional help. Any suggestions?
     
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  29. BrianGordon

    BrianGordon New User

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    On occasion I read these threads with some interest ... generally I choose not to comment though I've made my findings on this subject, based on extensive research, very clear on this board in the past.

    I do and have worked with some of the best minds in tennis and sport science and must say John Yandell is an expert whose opinion I respect greatly - I know him well and though we disagree on some issues, he walks the walk and is only interested in the truth.

    While interested in everyone's opinion, I feel compelled to mention that the data referenced is far from "inexact science" - in fact, it is based on academic research and methods developed over decades, some of which I've conducted myself - and research submitted to scientific peer review utilizing measurement systems that are exceptionally advanced and accurate.

    So please continue the interesting debate, but please give more thought before dismissing the science as "inexact" - if you are really interested in how we determine the contributions I will be happy to forward my published work on the subject - pm me - thanks - Brian
     
    Last edited: Aug 23, 2010
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  30. bhupaes

    bhupaes Professional

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    Hey Brian, lest I gave you the wrong impression, let me point out that I have the greatest respect for your work, and have read every article of yours I could lay my hands on! My post was prompted more out of curiosity and bafflement than anything else, and it is certainly not a dismissal, which I am not qualified to do. I also momentarily forgot that you have done some seminal work on these issues, or I would have addressed you directly. I will send you a PM - thanks for the offer to enlighten me on this very interesting topic!
     
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  31. CoachingMastery

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    Short of having you upload a video, post it, and have me analize your technique, I can only suggest you study what you know you should be working towards, emulate those elements that you know you should be doing, and do it all at speeds that initally are slow enough that allow you to feel the difference in the new methods. (Swinging too hard will almost always make you revert back to your old habits.)

    One thing that I hope is not taken as a plug for TennisOne is the ability for members to put up their own videos and play them side by side with the pros from the same angle for the same serve, etc. This is probably the best tool (sort of like Dartfish but without the bells and whistles!) that you can use to help identify patterns that are or are not working.

    But, even if you just video taped yourself and looked for various patterns, I think you will quickly identify areas that are deficient!

    Good luck!
     
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  32. papa

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    Yes, this is true (in the study 30% for a flat serve only) but nobody has mentioned that the same study says things like "movement is often incorrectly called wrist snap" & "novice players often strike the ball with the wrist flexed, while moving the hand at the wrist joint into further flexion". But it also seems to me that the major thrust of the article(s) were related to "upper limb" rotation and not about wrist snap.

    It seems to me that we have several "different" discussions going on at once here at different levels of understanding of the sport and the serve.

    I've been around this sport for quite a bit of time now and just might be one of the older posters. John Yandell and Dave Smith are not now or ever have been out to trick or mislead anyone - you can take that to the bank.
     
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  33. GuyClinch

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    I don't really disagree with the motion. Obviously Nadal hits pro quality serves so of course its accurate.

    I don't want to get wrapped up in the minutae of whether you consider this or that motion to be snap. Tennis pros do not use such specifity when describing 'snap' they just mean that you should engage your wrist muscles. When Novak is talking about using the wrist - its just that using the wrist muscles.

    The question really is do you believe the muscles in the wrist are along for the ride or a significant source of serving power. As I said before it seems that many tennis pros, biomechanics experts and playing pros disagree with this theory.

    As I pointed out studies show that a for a baseball throw the wrist muscles are a significant source of throwing power - and from what I gather its much the same in football with 'wrist snap" drills being an established part of football training.

    it seems your jumping through hoops to try to find support for your theory about the wrist muscles being along for the ride. From what I gather from your previous posts you are now positing that the wrist does move far enough for wrist flexion to be a significant source of power..

    This is sounds pretty much like a textbook case of confirmation bias. Now if you want to claim that the wrist muscles are in fact an active source of power for the serve - we are in agreement and I am sorry if I miscategorized your research.
     
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  34. spacediver

    spacediver Hall of Fame

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    can someone provide references to all these studies that examine sources of power? I'd like to look up the original articles and examine the methodology in more detail.

    So far I've found the following:


    Gordon BJ & Dapena J. "Contributions of joint rotations to racquet speed in the tennis serve", J Sports Sci. 2006, 31-49.


    Elliott B C, Marshall R N, & Noffal G. "Contributions of upper limb segment rotations during the power serve in tennis", J Appl Biomech 1995, 11433–442.



    Any others I should look at?
     
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  35. spacediver

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    K i've just skimmed through the first one, by Brian Gordon and Jesus Dapena (nice to see you posting in this thread Brian). Seems like a very rigorous video analysis of the motion - lots of geometry and math... and in principle seems like a viable way to infer the relative contributions of each joint to the final velocity.

    Still, in this study, as far as I can tell, there is absolutely nothing that can be directly infered about the relative muscular contribution. In other words, the 30% attributed to wrist flexion may have been completely passive.

    GuyClinch, in the baseball study you bring up that showed the role of wrist flexion, you mentioned that they determined that the muscles involved in wrist flexion were a source of power. How did they determine this? Can you provide the reference please.
     
    Last edited: Aug 23, 2010
    #85
  36. GuyClinch

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    If it's passive its not contributing any power. <g> What exactly would 30% of power "passive" mean? That makes no sense.
     
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  37. spacediver

    spacediver Hall of Fame

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    From what I understand, they calculated the velocity of each joint and compared it to the velocity of the racquet head. Nothing about power sources...

    At the very most, one could say that 30% of the power is channeled through the wrist joint, but that doesn't mean the wrist joint supplied that power originally.
     
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  38. GuyClinch

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    Fujii, N, Hubbard, M. Validation of a three-dimensional baseball pitching model. Journal of Applied Biomechanics, 18:135-154, 2002.
     
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  39. spacediver

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    Thanks, am getting it now. Having just read the abstract it seems as if it's only a computer simulation, so bear that in mind.

    Still, it seems as if they may have incorporated muscle action as a part of the model so it may be interesting.
     
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  40. JohnYandell

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    Guy,

    Glad the video helped and great if you now have accepted that there isn't forward flexion.

    This might further reduce your confusion. The biomechanical work is measuring racket head speed, not power. Not sure what that is anyway, "power," strictly speaking.

    Brian's study on Tennisplayer shows the wrist flexion is contributing about 25% of the racket head speed at contact, if I recall. What that means is the movement of the wrist from the laid back position to the neutral position is contributing the speed.

    Understanding what generates that movement in terms of actual muscle contraction is a different issue. That is not what is being measured.


    Brian himself and other scientists have postulated the idea that the forces of the upward swing may be responsible. Things can move very fast as a consequence of other motions--think of the tip of a whip.

    If you know of actual studies of the muscle contractions in tennis, would you be so kind as to cite them?

    Or maybe these experts are wrong. Or they may discover new evidence and change their opinions. Brian has told me that further analysis, developed since he provided the motion dependent torque theory, infers muscle activity--but does not measure it directly. If so great--it doesn't change my argument.


    You are basing a lot on one sentence from Novak and there are plenty of other great players with multiple grand slams who don't make the same claims about knowledge of technique. I believe Novak has one Slam while Mac and Pete are up there with over 20 between them.

    You have said your tone isn't hostile or condescending but you state that I am changing my argument in order to accomplish confirmmation bias, whatever that is. Not true and I would appreciate it if you stop making false statements.

    Either you didn't read my work closely or you forgot what was there, because first, I have always acknowledged the movement of the wrist and my whole argument about forward wrist snap hasn't changed.

    The whole goal should be to have players go through the right positions. You've stated how much the wrist snap helps you, great. Post some video and let's see.
     
    Last edited: Aug 23, 2010
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  41. spacediver

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    I skimmed through that baseball article, and it was difficult for me to make too much sense out of it (not my field).

    They did analyze high speed footage of a human pitcher and I think they also ran a simulation with torque generators as part of the model.

    I believe they estimated active torque (vs. passive torque) by analyzing the velocity of each successive joint in the kinetic chain. If a successive joint moved faster than it should have (assuming passive channeling), then the extra velocity was attributed to active torque (power generated by the muscles controlling that joint).

    I wasn't able to decipher the data well enough to see whether and how much active torque they measured at the wrist joint, unfortunately. Perhaps someone else more fluent in this field would fare better.
     
    Last edited: Aug 24, 2010
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  42. spacediver

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    John, am quoting your last post in case it gets missed. I feel somewhat responsible for shoving you off page 3 :)

     
    Last edited: Aug 24, 2010
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  43. GuyClinch

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    It sounds to me like that contradicts any "passive" theory, no?
    Why not incorporate additional muscles into your swing if you can? Its hard to fathom that its better to ignore them..
     
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  44. GuyClinch

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    Well if Novak and Blake don't convince you I kind of doubt my serves will. <g>
     
    Last edited: Aug 24, 2010
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  45. tiochaota

    tiochaota Semi-Pro

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    Finally I have a thread that has so many replies! Ok so does everyone agree I have to be as relaxed as possible when serving? But if too relax how to hit a powerful fast serve?
     
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  46. JohnYandell

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    Yes, likely it wouldn't.
     
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  47. spacediver

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    No it does not contradict anything. I was describing the methodology as I understood it. In other words, that technique is what they used to assess active torque. I never said that they did indeed discover active torque generated in the wrist joint.

    Thus far, you've not backed up your insistence that the wrist is a source of power with any evidence. One of the papers (the video analysis of the serve) does not make any active torque claims. The other paper (the baseball one) may or may not make that claim, but at this point, neither you nor I are capable of parsing through that study well enough to discern it.

    A wise stance in this case (for both you and I) is to remain agnostic about the issue until we can find/make sense of a study that sheds light on the question.
     
    Last edited: Aug 24, 2010
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  48. spacediver

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    and a comment about blake/djokovic... even if the wrist passively channels the energy, the wrist is still being "snapped". In fact, it may even feel like one is consciously snapping the wrist in such cases.

    To get a clearer view of their understanding of the role of the wrist, one would need to sit down and ask some more incisive and penetrating back and forth questions.
     
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  49. GuyClinch

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    ^^^Sure - but it could be the wrist muscles adding power - you know like every other link of the chain. <g> No one said Yandell was proven wrong - it's the proven RIGHT that is the problem is science.

    This is why the 'whip' analogy is not perfect. A whip is of course dead and only channels power from your snap. Your arm, legs, core and shoulder all have muscles that can be used to power that 'whip."

    Even with regards to the 30% number - if we assume that's "passive" that's just convient for the argument. How do we KNOW this?

    It's just like the forehand - the pronation adds power to the Federer forehand.. or the backhand where the supination adds a bit of power to a OHBH.

    Again to me this FEELS obvious. The OHBH is a perfect example because you can swing and hit it fine without using your wrist at all. But you can add in some wrist movement. It doesn't take a rocket scientist to figure out that adding in this motion will add a smidge more energy to your ball in terms of spin.

    Truth is in all the throwing sports - basketball, softball, frisbee, baseball and football wrist "flick" drills are an established part of training. Is all this training incorrect? Perhaps but certainly any proof of this has to be provided.

    Like I said initially its not well established that the wrist isn't used in the serve. It's just a theory.
     
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  50. GuyClinch

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    That's pretty weak - they clearly make that claim just because you don't understand it doesn't mean there is no evidence. Anyway since ancedotal evidence backs up the idea of active torque being generated the onus is on you to provide evidence for the wrist is dead theory..
     

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