Roger Federer and Modern Technique

Discussion in 'Tennis Tips/Instruction' started by JohnYandell, Mar 19, 2011.

  1. chico9166

    chico9166 Guest

    In layman terms "extension" is the upward and forward movement of the arm outward. (driven by the shoulder) YOu see this in varying degrees (roughly measured by the distance between the hand and torso) and is combined with varying degrees of hand and arm rotation.
     
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  2. sennoc

    sennoc Guest

    It adds nothing. It helps to prepare muscles for fast pronation what increases power. It's important to understand that fact: the source of energy is pronation, not a "delayed wrist". "Delayed wrist" helps to pronate.
     
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  3. 5263

    5263 G.O.A.T.

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    You don't understand that you can swing a shorter stick faster than a longer one, like when figure skaters bring their arms in? Wrist lay back makes things shorter.
     
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  4. SlowButSure

    SlowButSure New User

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    Yikes.

    I'd stay away from using physics in your argument if you don't understand it.
     
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  5. sureshs

    sureshs Bionic Poster

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    That is when you compare two situations of rotation, and convert from one into the other. Angular momentum is conserved, so folding the hands in (decreasing radius) increases the speed compared to the previous situation. It only holds when the performer has stopped trying to generate more torque and is just executing this action of conservation.

    In this case, there is a brand new production of torque in each case. In fact, for the same angular velocity, the longer stick will have more linear velocity at the tip.
     
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  6. 5263

    5263 G.O.A.T.

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    Hey, maybe I'm off on this, but
    are you saying you can hold the racket straight out and swing it just as fast as you can with the same effort with a bent elbow and the racket dragging in tow?
    Isn't that why choking up on the handle helps so; by making it shorter so you can move it faster?
    I know it works that way for me.
     
    Last edited: Mar 21, 2011
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  7. spacediver

    spacediver Hall of Fame

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    Ok, so extension refers to the motion of the arm along all three axes:

    upward
    forward
    outward

    correct?

    Why on earth would you want the arm to move outward?



    I'm getting the impression that nobody really knows what they're talking about when they talk about extension in this context. People just throw the term around vaguely, and describe it with a lot of hand waving.

    Let's start from the basics:

    Is extension a description of the movement and angle of the racquet head through space?

    OR

    Is extension a biomechanical motion?

    If it's the former, then I'm assuming that extension is achieved through a complex interaction of multiple biomechanical movements.
     
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  8. 5263

    5263 G.O.A.T.

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    I think the idea for why is in classical tennis it was to increase control and power thru staying on line longer.

    I think you are correct about the complexity of the movements in this classical approach to things, which results in a loss of power and control, which was the original goal.
     
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  9. 5263

    5263 G.O.A.T.

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    Maybe the skater was a poor example.
    Hey, I've been wrong before, but I don't need the formulas to get the common sense of how making things shorter helps me to swing them easier and faster.
    You disagree with this?
     
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  10. spacediver

    spacediver Hall of Fame

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    How does moving the arm outward allow you to stay on line longer?

    By outward, I'm assuming chico was referring to moving the arm away from the body to the side. So if you stand facing north, and punch the wall to your east, that is how I interpret moving the arm outward.
     
    Last edited: Mar 21, 2011
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  11. 5263

    5263 G.O.A.T.

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    I would expect outward to mean towards the target, as in outward towards the target.
    I suppose outward could be used in any direction away from the body, but in tennis my references are mostly related to contact point and target.
     
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  12. spacediver

    spacediver Hall of Fame

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    if outward means towards the target, then what does forward mean?

    btw I made an error - it was chico, not sennoc, who wrote this.
     
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  13. sureshs

    sureshs Bionic Poster

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    Not sure about that. Was just commenting on the ballet/diving example. I know that some pros like their sweetspot towards the head tip because that is the part which swings faster compared to a lower part. Same reason why we are told to extend up into the serve - one reason is height, other is the leverage.

    Take Karlovic for example. Why are his serves fast? Isn't it due to longer striking length? I meant in that way. If Roddick and Ivo both swing the frame equally fast in terms of angular speed, Ivo will still get more mph on the ball because linear velocity = radius*angular_velocity
     
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  14. 5263

    5263 G.O.A.T.

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    Not if they swing the frame equally fast...
    the frame speed is the frame speed, closer or further.
     
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  15. sureshs

    sureshs Bionic Poster

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    There are two kinds of speed, angular speed and linear speed. For a given angular speed, linear speed will be larger for the longer lever. You can think of angular speed as the rpm which would be observed if both of them completed the swing arc into a full vertical circle, and then kept up that rotation.

    There is no single frame speed. It varies along the length of the frame, and is very high at the tip. That is why you sometimes see motion blur causing the tip to look bent backwards when using inferior camera settings. People have been fooled into thinking that it was due to flex in the frame.
     
    #65
  16. 5263

    5263 G.O.A.T.

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    I took the words right out of your post.

    I think you meant to say that if the both had a swing with the same speed in to terms of....
    that the taller players frame would be moving faster....
     
    Last edited: Mar 21, 2011
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  17. Off The Wall

    Off The Wall Semi-Pro

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    From a layman's standpoint, if you wanted to be quick, make short radius strokes. If you want more power, lengthen your radius.
     
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  18. 5263

    5263 G.O.A.T.

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    A reasonable man.
     
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  19. sureshs

    sureshs Bionic Poster

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    How do you change the radius on demand? Are you saying choke up on the racquet or keep your racquet closer to the body? Sure, it will make the reaction time faster, if the ball cooperates with you by being where you have brought the racquet in. If the ball is wider, and you are reaching out to hit a volley or return a serve, you will not be able to make the radius short. You can only make the swing short.

    And increasing the radius produces more power for the same mass by increasing the velocity at the point of impact.
     
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  20. enishi1357

    enishi1357 Rookie

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    hitting early make more sense. i guess in this case federer made a bad decision choosing that shot selection
     
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  21. toly

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    Last edited: Mar 24, 2011
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  22. Off The Wall

    Off The Wall Semi-Pro

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    The whole question presupposes you have the time to decide. Not reflexing or stabbing.

    Your elbow makes a great extension tool.

    If the ball is coming deep and hard, you'll probably want to put a little bend in your elbow to control while capturing your opponent's power.

    Conversely, if it's a short bouncing ball, you'll want to exert more power...unfold.
     
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  23. bhupaes

    bhupaes Professional

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    IMO, one of the reasons for laying the wrist back is to increase the distance over which energy is released to the racquet head. At some point in the forward swing, the wrist is fully laid back. As the racquet nears the contact point, it is pulled sharply upwards and across causing the characteristic elbow bend, and this is where the "release" begins and the wrist (assuming it is reasonably loose) starts flexing forwards. The laid back wrist enables a larger arc over which the racquet head can accelerate and gather serious speed.

    You can try this experiment with a shadow swing. Note how the wrist leaps forward at the point where you pull up and across, if you hold it loose. When hitting a real ball, it doesn't flex so far forward because of the ball's impact, I guess - which is why a lot of people believe that the wrist does not flex forward significantly at impact... IMO as a low level amateur player, of course. :) Feel free to disagree.

    Of course, the laid back wrist (equivalent to pointing the butt of the racquet at the ball) has other benefits which have been discussed many times. To toly's point, it enables greater spin when coupled with pronation and upper arm rotation. It also moves the contact point forwards into a more optimal power zone. Even if the wrist is tight (inflexible), one can still get the spin benefit with the laid back wrist, I believe, if not the power. There are probably a lot of variations in between, in keeping with my belief that there are many ways to hit the ball.
     
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  24. toly

    toly Hall of Fame

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    Hi bhupaes,
    I do not understand the term energy release in reference to kinetic energy. The kinetic energy describes the moving object which is already released. If you are talking about potential energy, that makes sense. But where is it in the wrist motion? People here already got lost with term extension.:???:
     
    Last edited: Mar 21, 2011
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  25. spacediver

    spacediver Hall of Fame

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    toly, I think he means the transfer of kinetic energy (or momentum), from one part of the body to another. In this case, the idea is to channel the energy into the hand/racquet through the wrist joint.

    You can think of it this way. Before transfer, the kinetic energy is spread throughout the body and racquet.

    By redistributing more of it into the racquet, you gain racquet head speed.
     
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  26. bhupaes

    bhupaes Professional

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    Hi Toly, I was referrring to the earlier discussion regarding laying back the wrist. Let me restate my sentence without mentioning the word "energy", as follows: laying the wrist back simply increases the distance over which the racquet head is accelerated. Hope this is clearer.

    As for the word "extension", its usage in this thread is intended to mean a linear motion of the racquet head towards the target, as opposed to moving the racquet head up or across, I think. I will leave it to the poster who mentioned this to clarify what was meant.
     
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  27. bhupaes

    bhupaes Professional

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    You are absolutely right, that's what I meant.

    Edit: An extreme example that illustrates the point I am trying to make is the reverse forehand.
     
    Last edited: Mar 21, 2011
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  28. JohnYandell

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    Wow you guys have gone a long way down the road with this.

    I think it's best to stay away from mathematics unless you have actually 3D data something Brian Gordon has developed. But I try to stay to descriptions of positions. I think we can say some very valuable things about the strokes in this fashion and about the effects that making certain positions have on the ball and the shot.

    The first thing I want to clarify is what extension means to me.
    Since the swing is on an arc, there is technically no such thing as swinging directly along the line of the shot.

    The hand and racket don't extend directly out to the target.
    They move upward and forward across the body.

    The point at which the hand and racket have moved the furthest forward (and usually furtherest upward or close to furthest upward) I call the extension point.

    Now go back and look at the original video:

    http://www.tennisplayer.net/public/tw/fed/

    Go to about the frame where the ball leaves the view. That is what I call extension. Notice how flat Roger's swing arc is (not from low to high but from left to right to the contact and then back to the left.) Notice how far it travels forward or outward as it (also) travels back to the left across the body. This position he makes is characteristic of a basic, aggressive drive.

    The hand comes across to about the left edge of the torso and the wrist is about at eye level.

    Make the full turn and the extension position--usually everything else will take care of itself.

    I think the way to do this is thru phyiscal modeling and the creation of mental imagery of these positions. Talking about them is interesting and necessary but not necessarily (and usually not) the path to change.
     
    Last edited: Mar 22, 2011
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  29. spacediver

    spacediver Hall of Fame

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    I just spent a few minutes experimenting with some joint movements, and found that I'm able to achieve a linear path of the hand, even without changing my wrist position during the stroke.

    I achieve this by externally rotating my shoulder while making the stroke. This only works with a bent arm. If the elbow is fully extended (straight arm), this doesn't work.

    The reason for this effect is that externally rotating the shoulder, while in a bent arm configuration, ends up rotating the forearm clockwise. This clockwise rotation of the forearm can perfectly match the counterclockwise rotation of the forearm that is due to the swinging of the upper arm around the torso. The net result is zero rotation, but the forearm linearly slides through space. (the clockwise and counterclockwise references apply to a right handed forearm, and viewing the "clockface" from above).


    Anyway, in roger's case, or at least in this particular stroke we are analyzing, this is a moot point, since his arm is straight throughout the stroke.

    By a flat arc, are you saying that it traces a circle that is parallel to the ground plane, rather than a tilted circle?



    I like what you're getting at here (at least what I think you're getting at):

    Focus on creating a curve through space that is traversed with such force that the length of this curve extends way out in front of you, and that it whips around to form a "q" shape (when viewed from above), and everything will fall into place.
     
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  30. chico9166

    chico9166 Guest

     
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  31. jmverdugo

    jmverdugo Hall of Fame

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    I like that he catchs the racquet with his left hand, in my case I focus on this whenever I am hitting too short or I am nervous.
     
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  32. Djokovicfan4life

    Djokovicfan4life Legend

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    Oh my, I suppose Federer's gone old school.
     
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  33. tennisplayer

    tennisplayer Rookie

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    Hello John, this is a great video that I think I've already seen on your site (not 100% sure). I've also read your very interesting article on the myth of the wrap. Putting it all together, I think what you are saying is that once the racquet has made contact with the ball at the end of the circular/flat arc, what follows (the wrap or any other type of finish) happens as a consequence, and not because of previous intention. Makes sense, since the arm is attached to the body, and has nowhere to go but around. I've always wondered whether the wrap movement starts before or after contact. Good material for discussion, that's for sure.
     
    Last edited: Mar 22, 2011
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  34. JohnYandell

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    I would say master your extension point, and swing to that and let the backward and/or around motion of the wrap happen, which it will if you are relaxed and have swung with any racket speed.

    Which wrap will depend on contact height and amount of wiper.

    Space Diver: I'll stick to what pros and other good players do--not the motions you think you can make in your living room!

    Visualize it as if you are watching from above. No matter the hitting arm structure, the hand and racket tip will follow a curve or arc from the start of the forward swing to the extension. Forget about whether it is moving high to low.

    The flatter and longer that arc the more extension and the more you have "hit thru the ball" to use a metaphor.
     
    Last edited: Mar 22, 2011
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  35. Ash_Smith

    Ash_Smith Hall of Fame

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    [​IMG]

    Back on topic a bit, and playing devil's advocate...Is there a case to say that the position Fed is in here is the position that MTM decries so much - extension towards the target line?

    Cheers

    Ash
     
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  36. JohnYandell

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    Now as for the wrist motion. One of the really interesting things in the Fed high speed footage--and there are dozens and dozens of additional clips on the site--is how much the wrist moves, or not, and when.

    In previous work I looked at hundreds of other high speed clips and players including Sampras, Agassi, Kuerten, and many others. Although you could sometimes see forward flex as the racket moved forward, the wrist was laid back to some extent in the overwhelming majority of cases, and sometimes the lay back was quite extreme at contact, approaching 90 degrees.

    Brian Gordon's biomechanical analysis shows that this flex to the extent it does occur adds something like 2% to racket speed. So clearly the idea that people have of snapping the wrist--at least snapping it forward to get racket speed is incorrect.

    So what's that flex about? Again I defer to the master who says that it's about positioning the angle of the racket for the shot direction.

    That makes intuitive sense to me because in my qualitative research I saw the racket being most laid back going inside out, and flexing the closest to netural on shorter, lower crosscourts.

    Now let's not confuse that forward flex with the right to left rotation of the wrist and the rest of the hitting arm structure. That movement is part of the wiper and driven I think by the upper arm. It probably adds significant racket speed, but most likely to the horizontial component to generate spin.
     
    Last edited: Mar 22, 2011
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  37. spacediver

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    Note I wasn't commenting on this particular forehand. I was merely making a theoretical observation that it is entirely possible to have a linear path through space with a bent arm forehand. I wasn't implying that this is what actually happens, although I wouldn't be surprised if players employ this technique to help aim down the line.



    by flatter, do you mean a wider radius of arc? or that it is more parallel to the ground plane?
     
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  38. JohnYandell

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    Regarding extension toward the target line:

    On this one you can see, following the idea of arc, that the arc or curve is quite flat, meaning that it extends further forward before coming across.

    That's characteristic of aggressive drives usually hit for depth. On this one Fed is wrapping around his shoulder with some wiper action, or what I also hand, arm and racket rotation.

    One of the key things to understand is that these two factors--extension and rotation--can be mixed in an infinite number of combinations. The trick is not to confuse the extreme with the norm.

    So breaking the wiper off faster, extending less, and finishing lower across the body with the wrap going around the torso has it's applications. Usually on low balls hit for heavier spin or angle.

    Which brings me back to the point I made in that thread that got vaporized--you can't generalize from one or even many random examples. This is why we have hundreds from all positions on the court on Tennisplayer.
     
    Last edited: Mar 22, 2011
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  39. JohnYandell

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    Yes the arc is closer to a straight line but not straight. And again you'll find that the data won't really support that theory --either down the line or inside out. Remember your torso is rotating right to left as well. So unless your are going stand rock still and try to manipulate your arm motion (and radically change your hitting arm structure in the middle of the swing--not a good idea) you are not going to move the racket straight out.

    Measured data could shed more light on the differences in the shapes of the swing curves in all planes.

    But I think it's more important--at least if you are actually trying to improve your forehand--to have a few positions you are trying to make rather than dissecting the motion into theoretical parts.
     
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  40. spacediver

    spacediver Hall of Fame

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    thanks for the clarification.

    re radical changes in hitting arm structure, I actually find the external rotation to be a very natural motion during inside out forehands or down the line. I just allow my arm to lag behind in space, similar to how the racquet drop lags behind during the serve. This allows the racquet to remain facing the desired target for a few more fractions of a second.

    You can simulate this motion sitting down at your desk.

    Place your chair such that you are facing north west, where the desk is north. So you're facing 45 degrees left relative to your desk.

    Now move your chair away from the desk (or towards it) such that the base of your wrist is positioned at the edge of the desk. Importantly, keep your elbow bent so that the angle between upper arm and forearm is about 90 degrees.

    Now try to "swing" your arm like you do in a forehand, maintaining this bent elbow, but aim to keep the edge of your wrist going straight along the desk edge (so a linear path, not a curved path).

    You will discover that there are two ways to accomplish this:

    One is to let the wrist gradually lag behind (gradual wrist extension).

    The other is to let the forearm lag behind (gradual external rotation of shoulder joint).

    You'll also note that these sources of counter-rotation, which keep the path of the hand linear, can only be "active" for a small amount of time. It's not as if you can make the entire stroke linear.

    I strongly suspect that these sources of counter-rotation need to be incorporated into any discussion of how extension actually occurs, biomechanically.

    That said, I do appreciate your point about not getting paralyzed by analysis, and being able to function in a top-down, goal oriented manner, where the student has a particular goal in mind (and body will follow suit).

    I would love to see data from Brian Gordon regarding the development of shoulder rotation during the stroke, and how it interacts with the desired target. From all the preliminary teasers that you and he have offered, I gather he has done analysis on the wrist joint and how it interacts with the desired target (i.e. control of where ball is hit).
     
    Last edited: Mar 22, 2011
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  41. 5263

    5263 G.O.A.T.

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    You might make a case with that vid, but IMO it would be weak at best. I think it is much more clear on his signature shot, the inside out Fh; how the flatter part of the arc is leading up to contact where the arm is the straightest, then with the sharpest curve of the arc starting at the contact and the bend in the arm starting to increase pretty quickly.
    and remember, it is the hand to watch, not the racket head.
    http://www.youtube.com/watch?v=GlHzxOK_TBY&feature=relmfu
     
    Last edited: Mar 22, 2011
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  42. JohnYandell

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    I wouldn't say weak. This is just exactly the problem I was referring to. Generalizing based on a limited number of examples.

    I just went and looked at 40 inside out forehands on Tennisplayer in high speed. There were 10 where the elbow broke off as qucikly and sharply as in the youtube example.

    20 were at the level of extension in the video I posted.

    10 were somewhere in between.

    But there is a further critical point. At contact and anywhere from 10 to 50 frames thereafter, the hitting arm structure (and Roger uses double bend as well as straight) is rotating as a unit, regardless of the degree of wiper.

    The more radical elbow bend, when it does occurs, occurs mostly well after contact.

    As I said, to have a complete forehand you have got to be able to hit a wide range of extension/rotation combinations, the more so the higher the level. You can see the differences in Roger by how high the hand is when it reaches his left side, by the spacing between his hand and his torso, and by how much the hand arm and racket have turned over.

    It's far easier to learn to extend first and then rotate more and rotate faster later. The extension shots are almost always the aggressive and (relatively) flatter drives. That's the money forehand that Roger or any good player hits on most winners.
     
    Last edited: Mar 22, 2011
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  43. toly

    toly Hall of Fame

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    Geometry of the Federer FH usually is very simple. He just rotates the straight arm around the shoulder joint and hand around the wrist. The angular speed of the hand is regularly much higher than arm speed. There is nothing like ‘special extension’ etc. Long after impact the straight arm brakes and elbow bends. See pictures (copied from Andy Fitzell APAS video) below.

    [​IMG]
     
    Last edited: Mar 23, 2011
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  44. spacediver

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    I'm not sure how much stock I'd put in the APAS system, toly. It's next to impossible to see the details on how their system works. I'd much more trust proper biomechanical data that is derived from actual sensors on joints; and if it's primarily camera driven (as APAS is), I want to see their methodology.

    It may indeed be an excellent technique for analyzing joint motions, but I'd like to see more info before trusting it.

    Furthermore, as John has noted multiple times, you can't generalize from one forehand - the APAS frames are from a particular forehand.
     
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  45. Ash_Smith

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    But you could make a case...

    Exactly John, I think we have both said this during this thread, using one example can lead to a very biased theory in terms of instruction!

    I really like some aspects of MTM instruction and have incorporated them into my own teaching, but it's the whole modern vs classical debate (marketing) which sets many people against it, especially when you look at clips like the above and can see elements of "classical" and "modern" (whatever those terms really mean!) tennis included!

    Cheers

    Ash
     
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  46. chico9166

    chico9166 Guest

    And to me, this is what defines a great forehand. Developing a feel, for shaping the swing in different ways, to get the ball to behave, and handle the huge variance in incoming ball characteristics and situations. Learning how these two components work in an "infinite number of combination" is key in being multidimensional, in terms attacking, defending, etc,etc.
     
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  47. toly

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    I see very good correlation of the APAS video with OP and FYB video. :)
     
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  48. JohnYandell

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    I know Andy personally and about his methodology. He has worked with Vic Braden for many years. They are filming six 60 frame per second cameras. This shot was filmed on the stadium court at Indian Wells.

    There may be some debate about the accuracy of the three dimensional data they derive from this (something I am not qualified to assess) but that has to do with the frame rate--not the methodology of marking points on video. That has been well accepted even in academic biomechanics.

    What I feel confident about is that this visual representation is quite accurate--at least as accurate probably as the two clips being discussed.

    The great thing is the view. You can see just how far the arm and racket extend forward and how shallow the arc is.

    Notice also the spacing between the hand and the left shoulder
    when the hand gets to the left side of the torso.

    This is the definition of great extension and undoubtedly accounts for the effortless, deadly rocket winners Mr. Federer produces time and time again.
     
    #98
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    toly Hall of Fame

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    Federer usually rotates his straight arm around shoulder joint, which is center of rotation. He bends his elbow long after impact, hence the radius of the rotation before impact is constant and arc cannot be shallow. That is practically just pure circle. And again, because the radius of rotation is constant there is no point in talking about extension.
     
    Last edited: Mar 23, 2011
    #99
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    toly Hall of Fame

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    Great observation!!! Absolutely agree with you.:)
    Nevertheless, maybe Federer eastern FH grip also is the reason for the increase speed of hand. If the racquet face is vertical, Federer can use wrist extension and then wrist flexion to rotate racquet. These motions have around 180 degrees range. Player with western/semiwestern grip has to use wrist radial deviation and then ulnar deviation. These movements have just around 90 degree range. And maybe wrist flexion is faster than wrist ulnar deviation.
     
    Last edited: Mar 23, 2011

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