The Forehand: Busting misconceptions once and for all

Discussion in 'Tennis Tips/Instruction' started by 10isfreak, Jan 11, 2013.

  1. 10isfreak

    10isfreak Semi-Pro

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    Many of you might have encountered the tennisspeed blog. In there, we do not get served the usual beliefs we hear during all too many lessons... we are greated with hard science, with a big pile of evidence and repports that overviews some beliefs regarding tennis. The question is whether they are accurate in part, as a whole or if they are simply wrong.

    I will just give you 3 key elements that he overviewed among others.

    Your swing path prior contact mostly controls the ball's launching angle -- i.e., ceteris paribus, the more vertical your swing path, the higher the ball flies before starting to fall. As you can read, it's not the most determining factor in generating top spin.

    The racket head is not perfectly vertical at contact, but is ideally tilted forward. Why? Because spin is about accelerating the edge of the ball and most of your energy is directed forward... so, trying to accelerate the upper edge of the ball should, in principle, capitalize on a lot of energy compared to trying to accelerate upward the edge that is behind the ball.

    There is a direct relationship between spin production and how low the ball makes contact with the string bed. The racket is nearly horizontal during ground strokes, so low actually means near the side which is closest to the ground, not near the throat -- just to clear up the potential confusion. A low contact ensures the highest spin/pace ratio (that is, you get more spin, less pace this way).

    Theoretical material and concepts are not purely useless, abstract things... If you actually know what pros do and how they do it, you're one step closer to doing it yourself: you just need to figure out how to incorporate these into your swing. From that point and on, you can go on the court knowing that you have a factually valid answer that is guaranteed to yield results. AND YOU GOT IT FOR FREE!
     
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  2. 10isfreak

    10isfreak Semi-Pro

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    I will leave pictures or explanations on some subjects the host covers if someone asks for them, but I'd recommand reading the author who's quite a bit better than me at explaning what happens.

    I hope that this sort out the confusion. Of course, feel free to leave comments or, after reading, express how your understanding evolve. You may as well comment about how it influenced your game play.


    In my case, I never got to hit as hard, as well and with as much spin as when I have put all this into practice. And, as good coaches will tell you, spin is control... if you own spin production, you own the whole court. And it did help me kick the hell out of pushers once and for all.
     
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  3. sureshs

    sureshs Bionic Poster

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    I have heard around 10 degrees. How do you reconcile that with your pics below? Is it that the racket face (in these cases) changes from vertical to slightly closed over the dwell time? Or the photos below are slightly before contact?

    [​IMG]
     
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  4. 5263

    5263 G.O.A.T.

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    Do you think you can tell the tilt from those photos?
     
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  5. arche3

    arche3 Banned

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    You can't tell because the view is from the back. And the height of the camera affects the perceived racket face angle as well. You don't need a physics degree to know that. There is no way to know. Has nothing to do with dwell time.
     
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  6. dominikk1985

    dominikk1985 Legend

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    the racket tilt is more to push a rising ball (early striking) down to flatten the path of the ball (since a rising ball tends to continue to rise after hitting the stringbed) not so much to create spin.

    watch the same player hitting the ball on the drop and he will hit with the same spin but a vertical racket face. the other reason for the racket tilt is that the ball is below the racket center when it leaves the stringbed (not at the moment of initial strike as the tennisspeed guy claims!) because the stringbed brushes upwards. this causes the racket to tilt.

    I think with his opinion that the racket tilt increases spin the tennisspeed guy is pretty much alone.
     
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  7. sureshs

    sureshs Bionic Poster

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    Not with 100% confidence, no. The grip might give a clue.

    Do you think they are tilted?
     
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  8. sureshs

    sureshs Bionic Poster

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    That is why it is so interesting to me. On most the non-flattening forehand slow motion vids I have seen, the racket face has been almost vertical, which tells me that the upward swipe is producing the spin.

    But there are also shots hit by Roddick and Isner where they go over the ball with a markedly closed face, and finish around the waist on the other side.

    So I think a closed face, especially with a W grip, can also be used to impart a lot of spin.
     
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  9. dominikk1985

    dominikk1985 Legend

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    #9
  10. WildVolley

    WildVolley Legend

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    SpeedMaster, who runs the blog in question, has shot video from the side showing a slightly closed racket face at contact. It should be noted that the pros don't always hit with a closed racket face at contact and, also, the racket face is only slightly closed. However, contra some early theorists, empirically you can lift the ball even with a slightly closed face if you have enough racket head speed and a slightly upward swing path.

    I'm convinced that video is the best way to see what is happening, rather than arguing about subjective feelings of pulling across, hitting thru, accelerating late or early. Who cares about these terms when we can just mimic the movement patterns of successful pros?
     
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  11. sureshs

    sureshs Bionic Poster

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    Well, what you are showing is the reaction of the racket at impact which causes a tilt.

    I think your point is that the racket face is not deliberately closed at impact, except for the cases when flattening is required.
     
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  12. luvforty

    luvforty Banned

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    the face is always closed in relation to the initial launch angle, because the string bed 'gives' on contact (pocketing)... so at separation the ball leaves the lower part of the pocket which is looking UP.

    same reason face is always open to the launch angle for slices, because the ball leaves the upper part of the pocket which is looking DOWN.

    try hit a few balls with a smooth sheet of metal, you will understand. (very little pocketing, therefore the launch angle almost always square to the face)
     
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  13. sureshs

    sureshs Bionic Poster

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    No luvforty, I don't agree with you about the last part. The open face in a slice is deliberate, not just a consequence of recoil.
     
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  14. sureshs

    sureshs Bionic Poster

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    #14
  15. jakeytennis

    jakeytennis Rookie

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    P.A.S. determines the ball's path
    P for swing path
    A for angle of the String bed on contact
    S for speed of swing

    All of them contribute to the ball path, but i think P contributes no more than A

    i like to keep P an S relatively constant, and just adjust my angle of racket to control my shots.

    here is some youtube videos i found

    http://www.youtube.com/watch?v=q8Sa1BYPctg
    and
    http://www.youtube.com/watch?v=fWd1woOEJIE
     
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  16. Cheetah

    Cheetah Hall of Fame

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    Also a closed face gives more spin just by being closed. Given the same racquet path and same trajectory of an incoming ball a racquet with a closed face will produce more spin than one that is vertical.
     
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  17. luvforty

    luvforty Banned

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    A is actually the angle of the pocket at the point that the ball separates from the strings.

    this is why you can hit a ball up with closed face, or down with open face.

    this is also why the same swing produces different launch, based on string type and tension.
     
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  18. sureshs

    sureshs Bionic Poster

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    ^^^ I have long believed that the pocketing in the dwell time holds answers to many mysteries. One of them that I understood was how the racket seemed to be moving up at contact on many first serves, but the ball came out a degree or so below horizontal. The answer I found is that the racket tip completes its apex turn during the dwell time in those serves, and actually launches the ball sightly down at the end of it.
     
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  19. TennisCJC

    TennisCJC Legend

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    I fully accept both of these myths as true.

    Yes, pros hit most topspin FHs with a sligthly closed face and underspin BHs with a sligthly open face. I doubt they think too much about this as it has become instinct for them.

    Yes, you will get more spin if you hit below center as long as the racket is slightly closed.

    Both of these indicate you are hitting the ball in the middle or even on top for topspin. You will encounter less resistance from the ball and it will result in more spin.

    Isn't there an article in TW Univ somewhere talking about hitting the top of the ball for a kick serve and how it results in the most spin.

    Having said I believe in the "myths" and believe that hitting on top results in more spin. I still visualize an approach to the bottom 1/2 of the ball for topspin. Actual contact may not be on the bottom 1/2 but my thought process is on the bottom 1/2. I practice/think "take the hand/strings to the lower half and pull up and across for topspin.
     
    Last edited: Jan 11, 2013
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  20. 10isfreak

    10isfreak Semi-Pro

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    You gave an explanation and that's it. He tested 180 forehands of some of the best tennis players he could find, picture per picture at 210fps.

    Who do you think we should listen to? The guy who has an opinion or the guy who has a tested opinion?

    Evidence speaks loud; ideas, not so much.
     
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  21. Cheetah

    Cheetah Hall of Fame

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    No. This is fact.
     
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  22. TennisCJC

    TennisCJC Legend

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    I agree - I view it as a well accepted fact.
     
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  23. sureshs

    sureshs Bionic Poster

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    1. I sometimes hit on top of the ball for the serve (usually due to a bad toss), and it does produces top spin, but it feels really weird. There is also a chance of it going into the net. But it can be done. If there is sufficient forward speed, the ball can make it over the net even when brushed over the top.

    2. I think the path to the ball has to always be from the lower half, and as you say the eventual contact may be slightly different.
     
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  24. Cheetah

    Cheetah Hall of Fame

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    ...........
     
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  25. 10isfreak

    10isfreak Semi-Pro

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    The face are virtually always closed, first. At the first approximation, they are always closed and you can't tell unless you have a super slow-motion.

    Here's Federer and Nadal. Yellow marks the face before contact, green is at contact and Red is after contact.
    [​IMG][​IMG]

    That's WAY more horizontal than what people on this blog think it is.

    "At impact for the forehands shown here, Federer’s racket face is tilted forward 11 degrees at impact and Nadal’s racket face is tilted forward 15 degrees (relative to a perfectly vertical racket face).

    And the racket path used by each player for the same forehand as shown above is interestingly the same: the racket for both Federer and Nadal are moving 18 degrees upward…"

    18 degrees... do you realize how flat this is? And they're not hitting winners, they're rallying with their practice partner! The host did what none of you did and what people like Oscar will never do: he studied it with thousands of pictures taken from super-high speed videos.

    Do you know how he compares these two forehands? If I recall, he numbers about 40 anatomical movements that both of these players share -- and some which aren't shared by most top pros.

    Why does Nadal hits loopy shots and Federer hits mostly flat strokes?

    "Nadal often swings on a much steeper upward path than Federer (especially on the clay) and this steeper path further amplifies the amount of topspin he generates by tilting his racquet face forward throughout his forward swing. Nadal’s steeper overall swing path (see below), combined with his extreme forward racquet tilt throughout his forward swing through impact, results in 25% higher topspin production, on average, compared to Federer, as well as a slightly higher launch angle off of the stringbed that creates a shot with a slightly higher trajectory."

    [​IMG]

    Nadal's forehand is indeed swung at nearly 30 degrees here... If you understood what I have been saying, you know what happened: loads of spin, but also a very high ball.
     
    Last edited by a moderator: Jan 17, 2013
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  26. 10isfreak

    10isfreak Semi-Pro

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    Some people are doctrinaires. They just like their ideas, even when reality diverge from it.
     
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  27. 5263

    5263 G.O.A.T.

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    I would expect they are, but can't say from those pics...not that I can tell.
     
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  28. sureshs

    sureshs Bionic Poster

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    Supposedly, the Wilson Steam 99S can give you Nadal launch angle with Federer swing path :)
     
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  29. dominikk1985

    dominikk1985 Legend

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    well this image supports my theory:

    not the hand tilts the racket forward, the ball does. that is the only possible explantion for the racket staying at the same tilt angle for so long and then sudddenly turn over.

    or is anyone suggesting the hand does this drastic move just in the moment of contact?
     
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  30. sureshs

    sureshs Bionic Poster

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    Very very interesting. Is there a pronounced going over the ball at contact in the dwell time, or is it just recoil?
     
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  31. bad_call

    bad_call Legend

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    this supports personal hitting results and now have outside analysis to support.

    dude - u made my day. i'm ready for a beer. :)
     
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  32. Chas Tennis

    Chas Tennis Hall of Fame

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    Some points -

    1) I believe that most racket face reorientations after the ball impact - the red shown in the excellent Tennisspeed illustrations above - could be closely correlated with how far off the racket centerline the ball impact is located. That is, mostly the impact torque during impact turns the racket. I've looked at this issue in a few high speed videos but not enough to be sure. For pros, I believe that if the ball hits on the area of the strings in the bottom half of the racket face the top edge of the racket tends to go forward (closes). And if the ball hits on the strings in the top half of the racket face the top edge of the racket goes backward (opens). The pros more consistently hit in the same part of the string face. On most videos of my strokes, hits are more random above and below the centerline. The racket turns up if above or down if below the racket centerline. What the racket face is doing can easily be seen in high speed videos. Where were the ball hits on the Tennisspeed illustrations?

    2) I have read more than once that the impact time between the ball and racket strings is very short (was it 0.005 sec? or 5 milliseconds?) and the racket effectively does not change orientation during the time that it is in contact with the ball. What is the research for that view? How fast does it change orientation and what is the effect of the elastic strings on the forces given to the ball.

    3) While the pros hit slightly top edge forward (closed), is the racket tending to open or close a little more just before impact? In other words what are the hand forces/torques doing at impact.

    4) Does both hitting on the bottom half of the racket face and using a slightly closed racket face make for better control as well as add topspin. Does the racket close slightly to cover the ball a little in the few milliseconds during impact? Also, if the strings are closed the top half of the ball is always impacted and vice versa.
     
    Last edited: Jan 11, 2013
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  33. dominikk1985

    dominikk1985 Legend

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    It's physics:

    when you push against an object at a point away from the center of mass it will rotate.

    and since the ball has inertia that rests against a change of direction the upward moving racket face will brush up the ball causing the ball being below center at some point. this causes the racket to twist and "go over the ball".

    the ball creates a hinge for the racketface to rotate around.

    the tennisspeed guy himself proves that the racket is not turned by the hand. at about 3:00 he shows a shot of federer with his racket face opening at contact on a above center hit
    http://www.youtube.com/watch?v=U6icR4QaI84#t=3m00s

    of course he believes that pros deliberately hit below center so that the ball can turn the racket over...
     
    Last edited: Jan 11, 2013
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  34. jmnk

    jmnk Professional

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    The racket face is slightly closed on 'normal' rally shots to compensate for the spin of the incoming ball. To hit the ball back, with spin, the spin of the incoming ball must be reversed.

    in a normal tennis shot, even if the ball travels with no spin, the ball will have spin once it bounces off the court. So in a vast majority of shots you always deal with having to reverse the spin.

    it has been noted that if you were to hit a dropped ball, which just bounces up with no spin, you would want to hit it with racket that is not tilted.

    This is all nicely discussed in this book http://www.amazon.com/Physics-Technology-Tennis-Howard-Brody/dp/0972275908

    obviously players may not be aware of any of the physics. they just know it through experience acquired over thousands of hours spent hitting the ball.
     
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  35. 5263

    5263 G.O.A.T.

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    Does it comment on the difference between taking it on the rise vs a dropping
    ball?

    And for PP, not any passive aggressive with my clipping above : )
     
    #35
  36. jmnk

    jmnk Professional

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    I do not have the book in front of me, but I recall that it indeed does discuss that too.
     
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  37. Cheetah

    Cheetah Hall of Fame

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    internal shoulder rotation
     
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  38. dominikk1985

    dominikk1985 Legend

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    No.

    If it was internal shoulder rotation or pronation this would not happen so suddenly. also internal rotation also closes the racket face when the racket and forearm are in line. however pros hit the ball with the wrist laid back which means the racket is staying at roughly the same angle but rotating around the arm.

    Test for yourself. take your racket and internally rotate the arm with the wrist laid back and then with the wrist and racket being in line. only in one case the racket will close.

    also why is feds racket face opening in the video at 3:00 when his arm is internally rotating?

    Internal rotation of the arm is very important because in greatly contributes to RHS but it doesn't close the racket face.
     
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  39. 5263

    5263 G.O.A.T.

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    Well, at least not that fast anyway.
     
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  40. dominikk1985

    dominikk1985 Legend

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    yes. it might cause a slight closing because the forearm and racket are not at a perfect 90 degree angle.
     
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  41. Cheetah

    Cheetah Hall of Fame

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    Yes it does close the face.
     
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  42. Cheetah

    Cheetah Hall of Fame

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    why? it's obvious isn't it?
     
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  43. sureshs

    sureshs Bionic Poster

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    Tell me something. I have one issue with this mini Nadal (though much older than him) and it was amplified today in the cold of the night. This guy has a unique vertical scoop top spin with open face which he has grooved over the years and hits it from anywhere. The ball spin axis is very horizontal, unlike the axes of other players whose spin axis is roughly parallel to their racket in the usual forehand swing, and your racket is also parallel to how theirs was when you swing (if at all I am able to explain this). Those axes are angled to the ground while this guy's is horizontal. So what I find is if my racket is in its usual arc at contact, which means the racket is not entirely horizontal, the spin is climbing up the string plane, making it difficult to control. Should the axis of the racket be horizontal at contact (NOT asking about string plane orientation)? That is not even always possible depending on the height of the ball.

    Need some quick solutions.
     
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  44. rkelley

    rkelley Hall of Fame

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    No, the racquet should not always be horizontal at contact. For higher contact points it's pointing more upwards generally and you're hitting more across the ball. For lower contact points it's point more downwards. There's a lot of variation possible here because you can raise and lower your hand and bend your knees. It also matters how far outside your body you take the ball. But an important shot to own is one where your hitting across the face of the ball more, on both fh and bh.
     
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  45. dominikk1985

    dominikk1985 Legend

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    on high balls you also sometimes want a closed face to get a flat or downward trajectory of the ball.

    against a chest high short ball you can sometimes just slap it down into the opponents field like you do in a table tennis kill.
     
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  46. sureshs

    sureshs Bionic Poster

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    So that confirms what I thought that the goal is not to keep it horizontal.

    Then what is the best way to handle this vertical spin which came from the opponent moving the racket not like the usual path most people have, but with a scooping motion, as if opening a drawer in a chest.
     
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  47. toly

    toly Hall of Fame

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    Usually a ball with a lot of spin has relatively low speed. If, for example, you try to block this ball and if it doesn’t dig into string bed but rolls on the racquet face then you have no control of the ball’s bounce. So, you should hit the ball with significant flat (normal) component of the racquet speed around sweet spot then ball certainly digs into string bed and you will be the boss. :)
     
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  48. sureshs

    sureshs Bionic Poster

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    You are saying neutralize spin with pace. But the problem is this guy's balls also jump up high with the vertical spin. Then what to do?
     
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  49. Cheetah

    Cheetah Hall of Fame

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    This is true. Nobody hits balls with pace and spin.
     
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  50. toly

    toly Hall of Fame

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    How should you return kick serve. To control ball’s direction of your return you have to hit it actively and meet the ball around sweet spot to avoid the ball rolling on the string bed. Don’t hit it passively. :confused:
     
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