Pronation versus "wrist snap"...

Discussion in 'Tennis Tips/Instruction' started by gzhpcu, Mar 22, 2009.

  1. gzhpcu

    gzhpcu Professional

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    Everyone is talking about pronation, but what is its real role to contributing to racket speed, as opposed to being a natural result of a good swing?

    Most articles discard "wrist snap", even though many pro players say they do it.

    Let's share thoughts on this.

    First, read this article: http://www.revolutionarytennis.com/download/wrist_snap_evidence.pdf

    The article quotes Brian Gordon's book Serve and Science. Brian Gordon is one of the few to really have done systematical, biomechanical analyses of the tennis serve.

    Interesting is his finding that:
    1) pronation contributes only to 5% of total speed overall in the kinetic chain
    2) wrist action contributes a whooping 24% of total speed

    Moreover, he states that

    or in other words, that players do indeed consciously "snap" their wrist when serving.

    The wrist snap sequence being defined as consisting of wrist extension, ulnar deviation, flexion.

    Some quotes from Stanley Plagenhoef's classic Fundamentals of Tennis:

    (my emphasis)
     
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  2. gzhpcu

    gzhpcu Professional

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    Have an old book written by Pancho Gonzalez. He said he did a "wrist snap"...
    [​IMG]

    Yes, I know they did not speak of pronation in those days... but if he mentions wrist snap, it means he was doing it consciously...
     
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  3. gzhpcu

    gzhpcu Professional

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  4. gzhpcu

    gzhpcu Professional

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    Some more thoughts:

    When coming up out of the bottom of the racket drop, towards the end of the trajectory, prior to ball impact:

    • forearm rotation turns the racket from on edge on to facing the ball for proper contact
    • the abrupt acceleration, causes the wrist to extend backwards
    • the wrist (and racket), if under a loose action only, will only start coming forward when the arm starts to brake (to transfer kinetic energy to the wrist)
    So the question is: can we augment this extension-flexion wrist action by consciously willing a wrist snap?


    Old-timers evidently thought so. From another old book of mine Stroke Production in the Game of Tennis by William Talbert:

     
    Last edited: Mar 22, 2009
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  5. theZig

    theZig Rookie

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    DISCLAIMER;
    I do not mean to belittle or insult anyone in anything I ever say. Should you find this proceeding example unnesessary, that is fine. I post this in hopes that SOMEONE reading this thread will benefit! Thank you.


    Get a soda can, a paper, a pencil, and some string. Wrap the paper around the can (Any cylinder will do, really) and draw a line with the pencil straight up and down the can (Line A). Now, draw a line starting from the same point going up again, but as you go up TURN the can (Line B) and be sure that your pencil is going straight up as the can turns. Get a string and measure the two lines. Line B will be longer.

    Assume that both lines are drawn at the same speed in terms of going "up" the can. The only difference between the two, then, would be that one line is drawn straight up while the other is drawn as the can turns. Line A would reference a straight up swing, while Line B would represent pronation. Now, lets work with the formula Acceleration = Distance traveled/Time taken. As said before, the time taken for both lines to be drawn was the same, however Line B was longer than Line A; therefore Line B has more acceleration. We will now refer to the "lines" as "swingpaths".

    Now, let us apply this to the formula Force = Mass x Acceleration to the tennis serve. Mass will be the same for both serves A and B (since your arm and racket do not magically adjust) , however as stated before the acceleration is higher on swingpath B and therefore Serve B will inheirently have more force.


    Things to consider
    As you have already stated, pronation itself is a result of a good swing. In otherwords, simply swinging up with your racket (Line A) is NOT a good swing! I oftentimes find that people who consciously attempt to pronate through their serves also tend to "arm" their balls. I feel this is a result of people not understanding how large a role their bodies really do play. While the swing is obviously important, I feel that proper rotation of the shoulders/hips, drive of the legs, and a number of other things to be equally important. For example, if one were unable to rotate his shoulders, he would not be able to swing properly! Understanding what the arm itself does is fine, but it is also important to understand the rest of the body.


    About your thoughts on the wrist snap:

    This is a tough one, in my opinion. I personally am in the camp that you do not need to purposely think about snapping the wrist. I feel that if the toss is in the correct position, and the correct swing is used, the "wrist snap" should happen naturally.

    I understand your point where should your forearm continue at a constant speed, your wrist would be "dragged" behind the forearm itself slows down, allowing the wrist which is moving at a higher speed to "snap out", much like a pendulum motion. However, given the fact that our arms are not perfectly straight , I prefer to think of it more of a whip. The same principle applies to a whip (The tip will not "snap" out until the handle goes in another direction), however this only applies if we are talking in one direction. For example, whips are often "waved" (I don't know the proper term) in two opposite directions (but on the same plane). A simple way to show this would be to take a string and go up and down, and watch the tip.

    The serve, however, has several different directions going on. In a previous thread, you discussed the racket drop and how it effects the serve. As the racket begins to drop, however, our bodies are begining to rotate and push up with our legs. This gets our swing going, however our arm does not need to slow down right before contact because the "handle" of our serve is not our shoulder, but our torso. As the body is being propelled up, and our shoulders rotating, that would be the "initial" action (Much akin to say, lifting up a string). The reason why we do not have to decelerate our arm is because our body stops moving once our shoulders have opened up and our feet off the ground, we hit a point where our bodies are no longer accelerating and we are coming down into the court. That action would be the "second" action (quickly bringing the string down). The whip involved here is the up-down motion of bodies. The core muscles act more like bending a plastic ruler, and then letting it go. The result is the majority of the energy used to pull the ruler back propels it forward as well. The shoulder rotation adds another dimension.


    Conclusions


    I feel that pronation is, as you said, a result of a good swing, but that you do not need to consciously think about snapping your wrist. My basis for this is that pronation is the most efficient way of increasing acceleration, and that same efficient swing also lends hand to a natural wrist snap, like the end of a whip.

    I would love to discuss this further with you and the other members of the board. Again, I do not mean to insult anyone or try and "prove them wrong". I am not here to "be the bigger man", but to discuss and learn more about tennis.
     
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  6. larry10s

    larry10s Hall of Fame

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    ^^^^^ great post. nice to have another analytical thinker in the discussion. yandell in an article "myth of the wrist- serve" if i can paraphrase correctly(john if you read this correct me) the foward motion or flexion if the wrist seen is not from a concious muscular contraction of snapping the wrist but the result of the combination of the left to right swingpath and pronation. after those 2 occur and contact is made the wrist will naturally go foward as the hand and arm relaxes after contact
     
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  7. larry10s

    larry10s Hall of Fame

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    another quote from brian gordon One could anecdotally argue that much of the wrist joint motion measured during the approach to contact during the serve is passively accomplished through motion-dependent torque. This joint motion, combined with that actively caused by muscular activity early in the upward swing, leads to impressive joint rotation speed leading into contact. So impressive, that any last ditched effort to increase it at contact by consciously "snapping the wrist" would likely be fruitless.
     
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  8. gzhpcu

    gzhpcu Professional

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    I am baffled at why you think you think you need to make a disclaimer to post your opinion, but then, you probably have more experience posting in this forum than I do, since I only started to get active recently.


    You make very good points and certainly would appreciate discussing with you or anyone else to learn more about tennis. I have been posting quite a bit on the serve not to influence persons to my way of thinking, but to get a kind of peer review and see if some of my ideas have any merit.

    I have been experimenting myself with consciously trying to flex my wrist at contact, and have the feeling that it really helps.
     
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  9. gzhpcu

    gzhpcu Professional

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    This is certainly correct. I just have the feeling that the flexing of the wrist can be increased if at impact point, if you consciously try to whip it across the ball.

    Try it out, see how it feels, and let me know.

    P.S. I remember someone having asked Ivanisevic a question on how he managed to have such a great serve and he replied: "I just toss the ball up and hit it"... or something to that effect... Sampras also was told his coach not to make him think about his serve. For those of us let talented, thinking might help us improve...
     
    Last edited: Mar 22, 2009
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  10. fuzz nation

    fuzz nation Legend

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    I can appreciate the inclination for a disclaimer, since some issues around here are sort of gospel for some of our pals. I've been shaking my head at the pronation issue for a while and I share the opinion that it is a result of things done correctly in a service motion - definitely not something to actively try and perform.

    I also don't see wrist snap as something that's accomplished by employing the muscles in the wrist in a service motion. I think that the wrist should be looser in a good serve than with pretty much any other shot. Once the racquet is accelerated upward toward the ball in a service motion, it's the arm/shoulder's action of stopping that forward motion at the grip end of the racquet that makes the racquet head snap past it - with a loose wrist effectively acting as a hinge. It might feel like those little forearm muscles are trying to help to "whup" the racquet head through the hitting zone, but I believe that good racquet motion in a healthy serve is generated with a passive wrist.
     
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  11. gzhpcu

    gzhpcu Professional

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    From an International Tennis Federation presentation on the biomechanics of the serve regarding the forward swing:

    You can see the whole presentation here: http://www.itftennis.com/shared/medialibrary/pdf/original/IO_24976_original.PDF
     
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  12. gzhpcu

    gzhpcu Professional

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    You might be right, but Brian Gordon thinks otherwise, as in the quote in my first post. I just know that it seems to work for me, but I might be fooling myself into thinking that...

    Lets do an experiment: without the racket raise your arm in a prior to impact postion. Now do two things:
    • first accelerate rapidly forwards (with pronation coming naturally) and a loose wrist, then
    • do the same, except, additionally try to consciously flex forward at impact

    Do you feel any difference? I seem to get a more pronounced whipping action and outward facing palm of my hand when i consciously flex at impact.
     
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  13. Kobble

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    That's because you have no momentum being transferred. The motion has to come from somewhere. If you can flex you hand at 100 mph, but the object is traveling at 110 mph, I don't think you can add anything to it.
     
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  14. BorisBeckerFan

    BorisBeckerFan Professional

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    What cleared it up for me was when I was around 12 and my coach said I wasn't attcking the ball with the edge of my racquet enough. If the butt of your racquet is pointing up during the racquet drop and you are swinging up at the ball with the edge of the racquet following through forwards and outwards with racquet face still leaning somewhat down the pronation and wrist snap should happen naturally. Your arm will due the pronating right before impact. I know some players conciously add wrist snap but I guess there's good examples of players who do and don't do this. When I'm really trying to get some extra juice from my serve I add some wrist snap.
     
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  15. junbumkim

    junbumkim Professional

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    I absolutely agree.

    If you drag the butt cap of your racket from the back-scratch poistion (when the buttcap is pointing toward the sky) toward the ball, then the tip of the racket is going to snap upward, the racket meets the ball, and the tip of the racket will sort of snap downward.

    This really is the entire process of pronation and wrist snap. Your formarm has turned outward (pronation), and your wrist has snaped.

    The aforementioned process is probably what you want to concentrate when you want to increase your racket head speed in serve.
     
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  16. BorisBeckerFan

    BorisBeckerFan Professional

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    One thing that I would like to add is if anything is not clear for whatever reason or you're watching a youtube video on the serve or whatever and it doesn't quite click, I really recommend getting a good instructor to help. I am not a teacher but have had the benefit of lesseons since I was young. There are many good tennis instructors around the world that can help all of this make sense. Even if you don't get regular lessons the serve is the most important shot in tennis and it's really worth it to have the basic mechanics of the serve locked down.
     
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  17. gzhpcu

    gzhpcu Professional

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    This article in Revolutionary Tennis maintains that the wrist snap is a conscious effort:
    http://www.revolutionarytennis.com/wrist_snap_evidence.html

    Here a couple of relevant quotes:

     
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  18. BorisBeckerFan

    BorisBeckerFan Professional

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    I am not stating that this "is the case" but simply offer this as a possibility.
    These two concepts of snapping the wrist conciously and the wrist snapping as a result of proper technique are not mutually exclusive. Maybe they could both be happening at the same time. When I snap my wrist there is no detraction form the momentum proper technique and has placed on the wrist. One of the keys here is fluidity.
     
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  19. gzhpcu

    gzhpcu Professional

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    That is also what the revolutionary tennis article says. I tend to think both can happen at the same time. If the wrist is loose, it will snap, I just have the feeling that by additionally consciously willing it, the wrist snap gets accentuated more.
     
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  20. BorisBeckerFan

    BorisBeckerFan Professional

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    Thank you for posting the article, I'm going to go read it right now.
     
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  21. Kaptain Karl

    Kaptain Karl Hall Of Fame

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    Oooh, boy! gzhpcu, you're trying to stir up some trouble, huh?

    "Snap" communicates to students really well. That's my experience.

    - KK
     
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  22. jmjmkim

    jmjmkim Semi-Pro

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    In terms of Golf, I think the Wrist Snap is equivalent to the "Cupping" effect that make the shot lose power, where as the probation is the use of leverage that takes the ball "inside-out" <- again a golf term, that adds to the "ball compression". I simpler words, the wrist snap is misunderstood by beginners, in trying to snap their wrist at the top of the swing. It should happen naturally as a result of the "chain", like the snap of the end of a whip. A lot of beginners try to force this snap, without making the other parts of the body lead up to this snap.

    In golf, a properly hit shot even sounds different, due to the compression of the ball at impact. A well stuck ball sounds "softer", whereas a "cupped" shot sounds like a "smack", like a slapping sound.

    I think "pronation" is like the golfer keeping a "loaded" or "Cocked" wrist during the swing, as it gets released past the impact point, in which the "hands turn over", the right forearms crossing over the left, during impact. The pronation of the serve, or even the forehand, seems to retain this "loaded" wrist angle until past the impact point, in which the wrist is released and the head of the racket overcomes the handle, thus generating a greater head speed, than merely swinging the racket at the same speed {butt end and the head end}, and trying to force a "snap" at the end.
     
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  23. bhupaes

    bhupaes Professional

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    If you look at this picture of Sampras that was posted in a related thread...

    [​IMG]

    ... one thing that stands out is the angle between the racquet and the forearm. I think it is this angle that contributes naturally to the wrist action or pronation. I liken it to a quarterback throwing a football. The more the angle, the more the pronation - but one cannot have too much of an angle, since one does need a reasonable contact height. The harder one tries to hit, the more one pronates (or snaps, whatever you want to call it). I can believe it happens naturally for the most part. I suppose most pros and advanced players add an intentional component to it for added speed.
     
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  24. gzhpcu

    gzhpcu Professional

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    In respect to this angle between racquet and forearm, it does increase leverage. I started a thread about just that here: http://tt.tennis-warehouse.com/showthread.php?t=249783
     
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  25. gzhpcu

    gzhpcu Professional

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    I agree that this happens if someone trys to muscle the ball by only snapping the wrist. In this case, the arm is kept tense and stressed. If, however, you keep the arm very loose, the pronation takes care of itself. You do not have to consciously pronate. It is just the result of the way the shoulder is built.

    This, however, is different: it is a case of just concentrating on snapping the wrist at the very last instant, to increase the wrist movement which occurs anyway (also as a result of the relaxed arm).
     
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  26. bhupaes

    bhupaes Professional

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    Sorry - looks like you are far ahead of me in this analysis! I will switch my focus to the new thread. Thanks!
     
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  27. gzhpcu

    gzhpcu Professional

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    Just another quote from Pancho Gonzalez, describing his serve in the book The Art of Tennis edited by Alan Trengrove, 1964, page 47:

     
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  28. SystemicAnomaly

    SystemicAnomaly G.O.A.T.

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    [​IMG]


    [​IMG]

    In these 2 pictures we can see ample evidence of pronation but the so-called "wrist snap" seems be be much subtler. To my mind, wrist snap implies a very deliberate, very pronounced wrist flexion. I am not seeing that here.

    This is not to say that there is no wrist flexion at all. As the racquet head moves up from the racquet drop, the wrist may very well be extended (laid back). If it moves from an extended position to a neutral position, then a flexion action has occurred.

    The problem is that when many people hear the term, wrist snap, they assume that the wrist snaps past the neutral position in order to make contact with the ball. Many tennis players & badminton players will make this incorrect assumption when told to "snap the wrist"

    To my thinking, the terminology is somewhat misleading. For some players, "wrist snap" can elicit a correct response, while others will be mislead by the terminology. When Pancho G or tennis coaches speak of "wrist snap" that may very well get the proper action from an advanced player but may very well confuse lesser players.

    If one uses the phrase, wrist snap, I believe that it is important to qualify what is meant by the phrase in order to minimize confusion.


     
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  29. gzhpcu

    gzhpcu Professional

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    I agree SystemicAnomaly

    As you say, the wrist snap is less visually evident than pronation. This perspective shows the wrist stretching backward...
    [​IMG]
     
    Last edited: Mar 24, 2009
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  30. SystemicAnomaly

    SystemicAnomaly G.O.A.T.

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    As I've mentioned previously (in other threads as well), I am not a great fan of the directive, "snap the wrist" and do not normally use it when teaching the serve. However, I will use the phrase for a few students in order to elicit a desired action from those particular students. It is not uncommon for coaches to use certain phrases or instructions to produce desired results, even tho' they may know that those directives may not be totally accurate.

    There have been several threads in the past year or two that have dealt with the validity of "wrist snap". Mark P's Revolutionary Tennis article has been discussed previously. My own philosophy on "wrist snap" is much closer to John Yandell than Mark P. Check out posts #24 & #26 in the first link below for some insight from both Yandell & from Hi-Tech Tennis:

    tt.tennis-warehouse.com/showthread.php?p=2889168


    For more direct input on "wrist snap" from John Yandell, Brian Gordon, and Jim McLennan (of TennisOne), take a gander at posts #4, #7 & #9 in the thread below:

    tt.tennis-warehouse.com/showthread.php?p=2899558

    .
     
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  31. larry10s

    larry10s Hall of Fame

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    must say i am more in the brian gordon john yandell camp. have not tried to add conciuos snap yet but intuitivelly by conciosly contracting muscles at that point i would be tightening up my forearm and hand. counter productive if you are tring to be loose. as rafa would say ?no?
     
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  32. gzhpcu

    gzhpcu Professional

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    However, Brian Gordon and John Yandell do not seem to be totally in the same camp in respect to whether or not the wrisp snap occurs naturally, or whether a conscious element is in it.

    Not so easy to figure this question out, I find. Maybe, it is ultimately a personal thing: do it if it works for you, otherwise leave it. I find it helps me. I don't think in terms of contracting, this, I agree occurs naturally, I think in terms of flexing forward (slapping left to right) at impact.
     
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  33. KerryJ

    KerryJ Semi-Pro

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    Can someone explain the difference between wrist snap, flexion, and pronation?

    I thought pronation was the wrist snap. Can someone describe wrist flexion and how it is produced?
     
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  34. SystemicAnomaly

    SystemicAnomaly G.O.A.T.

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    Pronation is a forearm rotation. When I hear "wrist snap", I think wrist flexion. Perhaps the graphics in the following thread will help:

    tt.tennis-warehouse.com/showthread.php?t=251377


    .
     
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  35. jmverdugo

    jmverdugo Hall of Fame

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    I think it depends also of what type of serve we are talking about. I personally "snap" my wrist on my flat serve a lot more and in a deffierent direction than I do it on my topspin serve.
    Also, I do focus on snaping the wrist, I understand why some people see the wrist snap as something that should be a follow up and a concecuense of the pronation but IMHO i have found that consciously snap my wrist helps me. No only gives more power and control both directional and depth, but it also helps me to correct any deficiencies I may have in a particular toss.

    This is just my opinion.
     
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  36. larry10s

    larry10s Hall of Fame

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    have to contract the flexors if you are ACTIVELY trying to do it
     
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  37. gzhpcu

    gzhpcu Professional

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    Right, that is what I do. It helps me as, apparently, it helps jmverdugo. Maybe it is really different from person to person. Not everything works for everybody.
     
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  38. larry10s

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    jmverdugo? translate please.
     
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  39. larry10s

    larry10s Hall of Fame

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    if it works for you go for it.
     
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  40. drakulie

    drakulie Talk Tennis Guru

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    I've video taped, at high speeds (600 fps), many lower level players who think they are "snapping their wrist forward". Not one video I have taken shows a "forward snap". Like wise, I have yet to see a high speed video of a pro "snapping their wrist forward" on a serve. They all pronate. What one thinks they are doing, and what is actually happening are two different things.

    This video, 2:34-2:45, clearly shows a rolling of the forearm, and no "wrist snap".
    http://www.youtube.com/watch?v=QgoCWFnS5kU

    That said, it has been an interesting read in here so far.
     
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  41. Djokovicfan4life

    Djokovicfan4life Legend

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    It seems that many get confused because lots of players define pronation as a rolling of the wrist. But last time I checked, the wrist is "connected" to the forearm, meaning that it cannot pronate without the forearm following suit.

    As you said earlier, when I think of "wrist snap", I think of flexion past the neutral position. I don't think that players should focus on this when learning to serve.

    FWIW, I remember attempting to serve with this "wrist snap" and barely breaking 80 MPH. Since then I've ditched that concept altogether and my serve is nearing the 100 MPH mark.

    Just saying, there are other factors at play besides a simple "snap" of the wrist.

    Matt
     
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  42. gzhpcu

    gzhpcu Professional

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    Biomechanically, Elliot has shown that the wrist plays a big role in the serve.

    It is all under what does one understand under the term "wrist snap". It is defined by Elliot as being: wrist extension, ulnar deviation, wrist flexion. Ulnar deviation is also relevant, not just the stretch-shorten cyle of wrist extension/flexion.

    The rolling of the forearm, as previously mentioned, is just the natural consequence of a relaxed motion following the anatomical structure of the shoulder.

    If the hand is flexed, a natural rotation of the hand due to the bone structure of the wrist turns the palm outward when the arm is overhead. This extreme flexion does not occur when serving, but occurs on an overhead smash when the lob is struck well behind the head.
     
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  43. Azzurri

    Azzurri Legend

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    IMO the wrist does not so much snap, but it more so breaks. The serve is not predicated on the wrsit "snapping" as it is the rotation of the shoulder, arm and forearm. The wrist breaks on a natural progression if you hold the racquet in the proper grip (continental I feel is proper for serve). If you hold the racquet in a near semi-western grip (for really flat balls) then there is NO wrist breaking anywhere near the same is if it were in a continetal grip. Drakulie has shown video proof there is no real "snap". There is pronation/breaking but whoever thought of the word "snap" seems to be using the word incorrectly. If you really "snap" at the ball, it will hit the ground way before it goes over the net.
     
    #43
  44. Djokovicfan4life

    Djokovicfan4life Legend

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    I know that the SSC occurs as one begins the forward swing and ulnar deviation plays a role as well. What I DON'T see is an intentional "snapping" of the wrist forward (in other words, ahead of the hitting arm/forearm).

    IMO, this forward snapping is what most people think of when they hear the term "snap". At least that's what I think of. Obviously you are talking about a different concept altogether that seems valid to me. But it's not how most players define a "wrist snap".
     
    #44
  45. gzhpcu

    gzhpcu Professional

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    Probably a lot of the misunderstanding, as Djokovicfan4life says, is semantical.

    Here is another research paper:

    http://www.ingentaconnect.com/content/tandf/rjsp/2006/00000024/00000001/art00005;jsessionid=7tnabrb8eaaeb.alexandra?format=print

     
    #45
  46. sureshs

    sureshs Bionic Poster

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    I always thought pronation was essential when trying to hit a flat serve with a continental grip. That is all.

    Otherwise, I just do the wrist snap. As Mahboob posted here recently, a nice drill is to hit some serves long outside the baseline, and some serves short (on the same side of the net) with a wrist snap, and then sort of average out the two tendencies in an actual serve. I definitely have to consciously bring my wrist down to keep the ball in the court.
     
    #46
  47. gzhpcu

    gzhpcu Professional

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    Pronation is essential. But it is the consequence of having done the proper motion in a loose, biomechanically stress-free fashion.
     
    #47
  48. Azzurri

    Azzurri Legend

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    a true wrist snap would mean the forearm stays stead and the wrist snops with authority down..correct? its a snap of the WRIST, not the forearm, shoulder and wrist. At the point of contact, the wrsit is pretty perpendicular, the wrsit only "snaps" (breaks) after the ball hits the string bed. If you snap down onto the ball would it not go straight down?
     
    #48
  49. Djokovicfan4life

    Djokovicfan4life Legend

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    Not if you have a crappy ball toss that goes behind your head. :)
     
    #49
  50. J011yroger

    J011yroger G.O.A.T.

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    As opposed to a good ball toss that goes behind your head?

    J
     
    #50

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