coming forward instead of pulling back

Discussion in 'Tennis Tips/Instruction' started by thursdayisgod, Jun 7, 2008.

  1. tricky

    tricky Hall of Fame

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    Technically, there is always weight transfer in all groundstrokes, whether you've been moving forwards, backwards, whatever. That is because there's hip rotation, which helps to distribute your weight from one foot to the other. The only times where there's truly no weight transfer is if you lock your hips through the windup and forward swing, or if your trunk is so contorted that it cancels out the balance.

    Sometimes you see a person hitting a ball while still moving backwards. In that example, the weight is still obviously on their backfoot. However, as they initiate the forward swing, the weight transfer -- which is the delta, shifting, or change in distribution of weight -- is forward. Their linear momentum is going backwards, but their weight transfer is forward. (However the degree of weight transfer is still low since the front foot would be off the ground, thereby limiting the hip rotation.) Similar concept exists in football; when you see Favre or Brady throw off the back foot, their footwork enables their weight transfer to still go forward so that they can still throw the ball with authority.

    This is important because weight transfer places your center of gravity (i.e. forward weight transfer = center of gravity in front of you.) If your center of gravity is behind you, your balance will be off and it's very likely you'll hit the ball into the air. If your center of gravity is not really in front of you, then you'll have problems with making clean contact through the ball regardless of the extension in your swing. (BTW, a common problem with beginning 1H BHs. Even if you run toward the ball, if you block your hips by crossing over with the inside foot, you effectively "brake" your weight transfer and your center of gravity is no longer in front of you, even though your body is still moving forward.)

    All that said, none of the above actually addresses how weight transfer actually gives you power in the open stance FH, or how much weight transfer actually occurs in the open FH. But it's just to say that even in a true "sit and lift" FH (which itself also transcends stance), where there is much less weight transfer and the center of gravity primarily goes up during forward swing, there is still weight transfer.
     
    Last edited: Jun 19, 2008
  2. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    Wow, I can't believe this is still going on...

    Now I recall why I stopped posting a while back. The whole process of coming on here and reading a thread and saying "oh, someone online said that 99% of pros use such and such, I will now incorporate this strategy into my own game!" seems silly to me. Stances are really a matter of preference. I think I'm like the only player to hit an open-stanced one hand backhand approach shot, which only came about after a lot of multiple-coach input and analysis. I don't think any of us who made the decision for me to use THAT versus a regular closed stance would EVER think of teaching it, or even ADVOCATING it to any of our students. Stances come about through play. What is most comfortable/versatile in THAT situation is what is important, and I will stand behind my belief that what stance a player ends with is a process of EVOLUTION, not a "you should use this, it's what the pros use". I teach the closed stance to all beginners. It is, for me, the easiest way to convey to students the proper transfer of weight required to hit with excellent technique. As time goes on, most players gravitate towards the semi-open or open, but many stay with the closed.

    It is a matter of what is comfortable for THAT player, it is NOT the place of any other player to tell you what you are most comfortable with. I liken it to goofy/regular stances when surfing, skating, or snowboarding. It is a matter of preference, they can be made to work.
     
  3. EricW

    EricW Professional

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    Bill,

    We are arguing how a modern forehand is hit when the player is balanced. The worst thing about debating tennis technique is that anyone can post a rare deviation or an off-balance stroke that disagrees. You've only posted 1 modern forehand in which the players center of mass moved forward. I could post 1000 balanced forehands that meet my criteria. This is because, when given a choice, the majority of pros will choose to hit a true sit/lift semi-open stance forehand. Do yourself a favor: Join hi-techtennis.com and browse the ATP forehand videos. You'll notice that the overwhelming majority of forehands meet my simple criteria:

    A player who moves along the X axis is off balance, a player who moves along the -Z axis has no other choice, a player who moves along the Y axis is using the sit/lift technique. And an open-stance forehand which is hit moving along the +Z axis is rare and most likely a product of poor position. Extremely slight movements in any direction can be considered negligible.

    You cannot say 100% for anything. For example, Wayne Odesnik hits a surprising amount of forehands with his center of gravity traveling in the +Z direction. However, the majority of ATP pros and high-level modern players do not incorporate positive linear momentum (movement in the +Z direction) when balanced.

    What I advocate is the preferred use of the true sit/lift technique. An overwhelming majority of ATP professionals prefer to use this variation of the modern forehand.
     
    Last edited: Jun 20, 2008
  4. EricW

    EricW Professional

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    IMPORTANT POST:

    Bill,

    As Quasar pointed out, during this entire argument you have been misquoting our stances as much more extreme and thus harder to defend. (Straw man fallacy)

    For example, we believe that the true sit/lift forehand is the highly preferred forehand technique among ATP professionals and high-level players. You have constantly misrepresented our stance as a complete disbelief in the very existence of any variance on the ATP tour.

    When the hell did we say any of this?

    How many times did I clarify that this discussion about the balanced back-court forehand?
     
    Last edited: Jun 19, 2008
  5. EricW

    EricW Professional

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    Fair enough.

    For one: Your hips are jammed and not able to rotate as effectively in the closed or neutral stance. Stance doesn't matter?
     
    Last edited: Jun 19, 2008
  6. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    EricW: I am hoping this "sit/lift" forehand you keep mentioning does not just imply bending your knees and moving straight up...calling this the "preferred" method is ludicrous. I don't know ANY high level player who prefers to not put their weight into the shot. You lose A LOT of power and weight on your shot if you don't have your body behind it. Please clarify what you mean for me.
     
  7. NamRanger

    NamRanger G.O.A.T.

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    That is exactly what EricW and Quasar is saying. There is no weight transfer, and leaning forward into the shot would disrupt the "consistency" of the shot. You should be perfectly balanced, and have no weight behind the ball, and use only rotational force to power the ball!



    Of course, me and Bungalo Bill attempted to reason with them that theoretical physics cannot always be applied to the real world, as there are many other different factors also. Both of them are just tennis theorists who have no true game play experience. Anyone who plays tennis at a high level knows that if you don't put any weight behind your shot, the ball is going nowhere.
     
  8. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    I am willing to give them the chance to argue the benefits, that's why this is a discussion forum.


    EricW: You may not be able to rotate "quite" as effectively, but for me, anyway, if I want to hit a really hard drive, closed is the way to go. With my body behind it, I can hit a forehand almost as hard as my first serve. This is with a closed stance. I use an open on most approach shots, simply because I can get more topspin action on the ball, producing a weightier shot. Stance DOES matter to an extent, if you want me to say that. If you want me to boil it down for you, stance matters depending on what you want to hit, I guess. Some things are more effective when trying to do certain things. There, you got me to say that.

    What I MEANT was that stance does not make a player. You can't go around saying ONLY this will work and it will work for everyone. I have seen a LOT of very, very good players hit closed on both wings and hit heavy topspin off of it. This is why I say "stance doesn't matter"; you can make anything work, and pretty much every stance is effective with certain players.
     
  9. EricW

    EricW Professional

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    NamRanger,

    It's ironic that you post an odd forehand from Federer that still fits my simple criteria. His center of mass did not move in the +Z direction during the swing. The step forward isn't a factor in the actual swing because he stopped completely before the initiation of his swing.
     
  10. EricW

    EricW Professional

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    Quasar has already discussed this in detail: Stepping into the ball is useful for less athletic players who need help generating pace. For a player who can easily hit pace, the true sit/lift forehand gives them the topspin they need to control this pace.

    Edit:

    We posted at the same time. You're completely correct, it is much easier to generate pace while throwing your momentum forward. (Center of mass traveling in the +Z direction, forward linear momentum, etc) However, for players who need no help generating pace: The true sit/lift forehand provides them with the control they need to be effective.
     
    Last edited: Jun 19, 2008
  11. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    Ok, fair enough. At least you have the sense to not argue THAT point. When you say "sit/lift", does that include the rotational "modern forehand", with the finish on the same side of the body as it originated (ie: Nadal)?
     
  12. EricW

    EricW Professional

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  13. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    Ok, thank you for clarifying. Even in his video, there is still foreward momentum on almost all of his "standing" shots. Let's exclude running shots, as most of those are not a prime example of technique and form. You can see his body moving into the shot on all the side views, especially early on in the video. I'm really failing to see what we're arguing about here.

    Edit: By "foreward momentum" i mean, he is coiling and then uncoiling INTO the ball. His weight IS moving into the shot. Just because his weight is not clearly finishing on his front foot does not imply that the body is neutral.
     
    Last edited: Jun 19, 2008
  14. EricW

    EricW Professional

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    At 0:16 his center of mass may be moving in the +Z direction. The camera angle makes it nearly impossible to discern whether he simply steps quickly out of his position upon landing after contact, or if his center of mass is indeed moving in the +Z direction. However, I don't see any other forehands that are against my stance.
     
  15. NamRanger

    NamRanger G.O.A.T.

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    lol, so you're saying that if they stop and swing it's still the same thing. Geez, that must mean they were hitting modern forehands back in the 1920s. Guys would stop before hitting the ball. The step factor means nothing. Honestly, who in their right mind is moving forward into the ball as they are swinging (assuming they have time to setup). What me and Bungalo Bill are talking about is the fact that Federer has LEANED his weight into the ball, which you can see from the video there. You can change your Z-Axis without moving your feet you know, which Federer does in that video.


    We could go on and on about this, but the fact of the matter is, you have absolutely no idea what you are talking about. Rant on about your Z / X / Y axis arguments. Me, Bungalo Bill, and the rest of the sane world will continue to use different stances depending on the situation, and continue to weight transfer properly in order to hit good strokes.
     
    Last edited: Jun 19, 2008
  16. EricW

    EricW Professional

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    All the movements are balanced by an opposite movement. This is evident from the fact that the players center of mass does not move in the X or Z axis in a balanced sit/lift forehand.
     
  17. EricW

    EricW Professional

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    No, in an old-school forehand a players weight moves forward during the swing. They would step into the ball during the swing. In the video you posted, Federer's weight does not move forward during the swing. How many ways do I need to say it? Just watch the clip, it's obvious.
     
    Last edited: Jun 19, 2008
  18. EricW

    EricW Professional

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    Not knowing specific jargon shouldn't exclude someone, but not understanding the sit/lift forehand would make it very hard to participate in this argument. In other words, assuming he understands the mechanics behind the sit/lift forehand, but simply hasn't heard the term "sit/lift".. it's all good.
     
    Last edited: Jun 19, 2008
  19. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    Even IF there weren't forehands from the evidence you provide that directly go against what you're saying, James Blake is still one player. The "sit/lift" blake is talking about isn't saying "don't move in the z", it's saying bend your knees and explode into the ball, which is what he is doing over and over in his shots, even in the video you provided. Look, the fact remains: you cannot produce the same pace on a forehand without moving into the ball. You have even agreed to this. It is indisputable, a law of physics.

    So basically you're arguing that stronger players don't do this (even though they could hit harder), because they need to harness their power. This doesn't make sense for the following reasons:

    1) Pros don't hit 100% pace all the time
    2) Pros don't hit 100% heavy topspin all the time
    3) It would be ridiculously tiring, no to mention stupid, to take a full effort swing in order to HARNESS the power of the full swing versus hitting the ball NOT as hard as they can all the time.

    So your argument really doesn't make sense. You're saying that a pro player, who is "athletic" enough to the point where they must EXPEND energy just to be able to keep the ball in the court, versus hitting the ball via a closed stance, or even an open stance, with momentum moving into the ball at 75% for both greater penetration AND power. You have ADMITTED that you can hit more power with an aggressive momentum versus a neutral weight. WHY would anyone in their right mind (especially someone with the means to analyze their own game via television) want to expend more energy for less result?
     
  20. EricW

    EricW Professional

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    Yes. In addition, choosing a more extreme grip forces you to expend more energy in order to hit the same pace because the spin is greatly enhanced. Why do modern players hit with more extreme grips than the players in the past even though it takes more effort to generate the same pace?

    On my average rally ball, I expend a lot of energy. I could hit the same pace with an eastern grip and stepping into the ball. However, the topspin allows me to control the ball better even though I am swinging harder. Not the mention the enhanced difficulty at handling heavy topspin.
     
    Last edited: Jun 19, 2008
  21. NamRanger

    NamRanger G.O.A.T.

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    This isn't even the point that Graham is making. Why would anyone in their own right mind swing nearly 200% harder (which you would have to do if you did not put any of your weight into your shot) in order to generate the same amount of pace? Yes, you have to swing harder with a more extreme grip, but the extra amount of spin pays off. However, for one to not use any weight transfer at all, you would have to rotate your body at an incredible speed and probably risk injury. Also, you would not be very efficient at all, as you would probably be swinging at least four times harder then the guy that does use his weight.
     
  22. EricW

    EricW Professional

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    Same deal with the true sit/lift as opposed to incorporating positive linear momentum. Sure you have to swing harder to generate the same pace, but the extra spin pays off. You've said it yourself. Come on man, keep an open mind.

    You can find plenty of clips where a player's center of mass doesn't move in the +Z direction. Do these players get injured regularly from this stroke?
     
  23. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    Lol, thank you, Nam. You saved me the trouble. The topspin, no matter how much, doesn't make up for the expenditure in energy required. If you swing the exact same speed, but apply the speed of one to hitting behind the ball while moving into it, and apply hte second to hitting your "sit/lift" (I hesitate to call it that, as what you're calling a sit-lift isn't what blake was implying) forehand, the results would be very dramatic. The first would be a deeper, more penetrating, powerful shot, the second would be a shallow, weaker ball with a lot more topspin, causing a jump on the ball. This is ineffective for the FOLLOWING reasons (I can do this all day):

    1) I would smack the crap out of ball #2
    2) The added topspin on ball #2 would stay in the court MUCH longer than ball number 1, giving the opponent more time to set up and smack the crap out of
    3) Ball #2 is not at all "damaging", unless the person is standing/lying in "old-ladies-land" and it would bounce at their feet, or for some odd reason your footwork sucks to the point where you can't use the extra time on ball #2 to allow it to fall into the "home run" strike zone

    That being said, you would LITERALLY need to expend 200% of the energy to make this strategy effective. That just doesn't make sense.
     
  24. EricW

    EricW Professional

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    GrahamIsSuper,

    These players use the true sit/lift technique for the same reason they use more extreme grips. I don't get how this is arguable. Do you also believe using more extreme grips is inefficient because you need to swing much harder to generate the same pace?
     
    Last edited: Jun 19, 2008
  25. MasterBruceTennis

    MasterBruceTennis New User

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    I am back, just FYI. This is for Jr. High and older players ever read this thread.

    Time T1=the moment initiate his swing
    Time T2=the moment the ball impact the racquet

    At T1, “he stopped completely” means the velocity V1=0

    Then, between T1 and T2, if his C.G has no +Z or –Z direction movement, means the acceleration at T1 is ‘zero’ too (a=0).

    So, between T1 and T2, his C.G perfectly stays on the XY plane.

    Can anyone make a robot to chase a (60 mph) ball within one second, stop and swing, like that?

    Nevertheless, if he have V or acceleration in +Z direction, that adds power to the ball, because, f=ma, momenturm=mv=ft=mat, where t=T2-T1

    If anyone do not believe this is true. One way to convince himself:
    Go tell all of the ATP men and women (especially Sampras) hit their forehand swing volley without Z direction acceleration and velocity.

    If this still cannot convince his ‘zero’ (XY) mind, then,
    Jump himself to the wall (put his weight in +Z) direction; see if it will hurt more with greater Velocity and acceleration.

    If this still cannot convince him, then make a XY plane and frame himself on it and hit every ball—without moving XY plane an inch forward or backward.

    I hope this help a bit.
     
  26. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    You can't say that someone is using specific footwork because of the grip on the racket, so don't. There's a difference between taking a "full" swing and having to swing 2 times harder to get the same result. What YOU are describing is the latter. What I and seemingly everyone else is advocating is utilizing proper footwork and movement to reduce some of the effort required to achieve the same results. You are advocating a technique that requires you to not move effectively and aggressively (question: why WOULDN'T you want to be moving foreward after an aggressive, penetrating forehand like we are describing?) and expend twice as much energy to achieve the same results as a traditional forehand.

    Do not misconstrue my argument against this "sit/lift" forehand of yours as an argument against the power of topspin. You are saying that Topspin alone is enough reason to expend twice as much energy. I will agree that topspin is an effective weapon, and worthy of expending energy to produce. So, we are agreeing on that point. HOWEVER, you are advocating the use of a technique that requires using MORE than enough and excessive amounts of energy to do what you can easily produce via simply moving into the ball.
     
  27. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    The only thing you can change if you're using the same exact swing path is the pace on the ball. It is literally impossible to change the spin on the ball without changing either the racket face angle or the swing path. I don't see how bending your knees and going straight up, yet using the same swing path, will have any effect other than losing energy that could be going into the ball if you were moving forward instead of straight up.

    I can't think of a single player who uses this "sit/lift" technique on every shot. Come to think of it, in my 17 years of tennis, I have never even HEARD of the sit/lift prior to this conversation.
     
  28. EricW

    EricW Professional

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    Answer the question. Do you also believe using a more extreme grip is inefficient because you need to swing much harder to generate the same pace?
     
    Last edited: Jun 19, 2008
  29. EricW

    EricW Professional

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    Graham,

    It's 3am, I'm getting tired. I edited that out of my post for a reason: It didn't make sense.
     
  30. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    No, you don't need to swing much harder to generate the same pace. I thought I made that clear. You can generate the same pace via a combination of moving into the ball and proper rotation. The two more than cover the lack of power that would otherwise happen. To say that it is feasible and it makes sense to expend 2x the energy to swing twice as fast instead of moving forward makes no sense, hence, why your version of the sit/lift forehand is not economical.

    Amen to that.
     
  31. EricW

    EricW Professional

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    The biggest thing that I don't understand is this: You're literally arguing that the true sit/lift forehand is inefficient and shouldn't be used. What about the 10000s of times you've seen an ATP pro hit a true sit/lift forehand? Are they as wrong as you think I am?
     
  32. EricW

    EricW Professional

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    If you utilize +Z linear momentum and correct rotation in 2 forehands: One with a more extreme grip and another with a less extreme grip, in order to generate the same pace with the more extreme grip as you did with the less extreme grip, you must swing harder. True sit/lift vs +Z linear momentum is the same (in this respect) as western vs eastern.
     
    Last edited: Jun 19, 2008
  33. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    Whatever dude, I'm sick of arguing with you. Have fun using your sit/lift forehand.
     
  34. NamRanger

    NamRanger G.O.A.T.

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    None of your ideas of balance and zero movement along the z-axis are recognized by any tennis authority. Basically, your entire theory is created by YOU, and has no one that supports it. Vic Braden and John Yandell would have a friggin field day picking your entire theory apart.
     
  35. Bungalo Bill

    Bungalo Bill G.O.A.T.

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    Who said this? Inefficient? I haven't read above but I know I didnt say that the open stance was inefficient using angular momentum. It is plenty efficient and effective.

    My argument is in weight transfer and hitting off the back foot. I think this thread may have gotten muddy but to say that angular momentum is inefficient in an open stance forehand would not be correct either.

    My position is this which seemed to get blurry when considering pure angular momentum:

    1. The open stance forehand is not only hit off the back foot. In fact, to hit more of an assertive forehand, a player will make contact with the ball with their back foot off the ground. A player that places his weight over the back leg and then torques their rotation (uncoiling) back into the ball increases their chance of hip injury. Once a player has lined up on the ball as the pressure of their weight moves over the back leg and coiling takes place, they need to move their weight back over to their front foot as they hit the ball and try not to hit through the ball while torquing over their back leg. Ihave provided plenty of evidence showing this.

    2. A player hitting an open stance forehand can and will hit with their weight moving backwards, forwards, and stablized. If a players center of mass moves in any direction, that is considered weight transfer.

    3. In an open stance forehand, there are other factors at play and one can not just consider angular momentum in its purest sense. You must consider:

    a) Translational motion
    b) Force
    c) Torque
    d) During movement, the center mass follows a parabolic path. This can be controlled and used with angular momentum.

    We are considering other factors besides angular momentum in an open stance forehand. For example, a coin standing on edge can be flicked into a spin by snapping a finger against its rim, and it will turn very rapidly while moving forward only slowly. Or, the manner in which footballs spin and move through the air is what we are talking about, not just pure angular momentum.

    When a player plants and turns back into the ball and depending on where the ball is and what the player wants to do, forward weight transfer can occur no matter how slight. It depends on what the player is trying to do.

    Forward weight transfer no matter how slight occurs more often then you give credit for due to momentum, force, acceleration, and movement. No one is denying that angular momentum doesn't occur. Angular momentum has been around for decades in tennis strokes, it is simply rising to critical mass.
     
    Last edited: Jun 20, 2008
  36. Bungalo Bill

    Bungalo Bill G.O.A.T.

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    Well that is not good. GrahamIsSuper needs to clarify his comment on this. I just don't believe pure angular momentum is happening in an open stance forehand. There are factors that are at play like force, momentum, and the other things I have mentioned.

    Regardless of whether or not we can actually see a persons center of mass move in a direction, based on the position of the feet and the push off from the ground, my hypothesis would be that there is more forward force in the open stance forehand then meets the eye.

    My position is only about whether weight transfer occurs and that a player should not make contact with the ball with their back foot on the ground. In some cases they will, but it is not something I recommend for hitting an effective open stance forehand and to avoid hip injuries.

    My other position is that angular momentum is not new. Angular momentum has been around for decades. It has been popularized and better discovered/understood due to more semi-open and open stance forehands being hit in the current game.
     
  37. EricW

    EricW Professional

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    What I advocate is the preferred use of the true sit/lift technique. An overwhelming majority of ATP professionals prefer to use this variation of the modern forehand.

    In the true sit/lift forehand, the center of mass does not move along the X or Z axis. Where does the +Z linear momentum come from if there is no movement forward? Momentum = Mass * Velocity. All motion in the true sit/lift forehand is in a circular fashion. Therefore all momentum is angular. There needs to be some sort of linear movement of a mass in order to say there is linear momentum. However, all motion (in the Z or X) is rotational.
     
    Last edited: Jun 20, 2008
  38. Bungalo Bill

    Bungalo Bill G.O.A.T.

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    Balanced or not, open stance forehands are hit with a player moving back, forward, and stablized. That is my point. You also are not considering that when a player pushes off the ground that even a slight shift in the center of mass of let's say 3 inches forward is considered weight transfer.

    As well as I could. I showed you THREE different clips supporting that open stance forehands are not only hit with someone just going up. this is so painfully obvious that I really dont want to embarass you over it.

    Look EricW, analyze video better. You have not answered the other factors involved concerning angular momentum. Is it because you failed to consider it? Do yourself a favor, get a book on angular momentum and read about the other factors at play - you might learn something. Once again, you will see a lot of forehands have forward, backward, stablized movement.

    I dont give a darn what you advocate. Open stance forehands are hit with a players center of mass moving forward, backward, or stabalized.

    Because you are faling to recongize my stance. You are saying that forward momentum in an open stance forehand RARELY ever happens!!! Bull!

    You are saying I only have 1 example to your 1000. Bull! You are full of it and you clearly show you do not know how to analyze video.

    Yeah buddy, you can consider Z, X, and Y if you want. If you do not include other factors that affect angular momentum that are clearly in play with a tennis players stroke, you are full of it.

    Weight transfer does and can occur in an open stance forehand. PERIOD.

    GAME OVER.
     
    Last edited: Jun 20, 2008
  39. Quasar

    Quasar Rookie

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    The thing about crazy people is that they don't know they're crazy.
     
  40. 5263

    5263 G.O.A.T.

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    You say this and it is sort of correct for the wrong reasons, as The shifting of center of gravity is how Linear Momentum is defined and measured. So you are correct that CG is a different thing than Angular MO, cause the moment the CG shifts, it is now Linear MO.

    It is also the very thing that defines that your "Angular" momentum does not actually exist in the best tennis strokes or only serves to lead into the creation of Linear MO.

    For example, a moving object has momentum in a reference frame fixed to a spot on the ground, while at the same time having 0 momentum in a reference frame attached to **the object's center of mass.**

    The amount of momentum that an object has depends on two physical quantities: the mass and the velocity of the moving object in the frame of reference. In physics, the usual symbol for momentum is a small bold p (bold because it is a vector); so this can be written:

    {p}= m \{v}
    where:
    {p} is the momentum
    m is the mass
    {v} the velocity

    Angular Mo is clearly distinguished from linear by having no shift in position (or center of Gravity), so we have little or no PURE Angular momentum in tennis, as rarely would a player spin that precisely around an Axis during an entire shot and with no upward vector either! Anytime you have wt shift or move of CG, you have Linear Momentum.

    If for discussion you want to include Angular aspects to tennis swings (very useful i'd agree), it would be inaccurate to overlook the Linear nature that BB cites and is nearly always present and desired.
     
    Last edited: Jun 20, 2008
  41. Quasar

    Quasar Rookie

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    If the center of gravity shifts forward while the body rotates the racket around then it is both actually, not just linear. But that is not really relevant to the point of the thread. What is relevant is whether using forward linear momentum or not is the optimal way to hit a powerful topspin forehand for an advanced or athletic player.

    What momentum is is obvious to me, I have not said anything inconsistent with it, certainly not anything that you have pointed out here. By the way you got the equation wrong, momentum = m times v, not m/v.


    This is an invalid assumption made by you. There are many times where the top players in the world hit a powerful topspin forehand with virtually zero linear move forward. I have said many times the the only place the center of gravity really moves is up. Read the thread more clearly, especially before foolishly using exclamation points. EricW is showing graphics with all the each axis represented even.

    If for discussion you want to include Angular aspects to tennis swings (very useful i'd agree), it would be inaccurate to overlook the Linear nature that BB cites and is nearly always present and desired. [/QUOTE]

    You have it backwards, you are overlooking the lack of linear nature in the modern power topspin forehand. Here are some videos of top players hitting forehands around 100pmh....watch the center of gravity (waistline) of each of these players as the make their motion, you will see that it only goes upward and does not really move forward.

    http://www.youtube.com/watch?v=PbsQ8gZLWyc

    http://www.youtube.com/watch?v=lFibX-inICg&feature=PlayList&p=4A754E1E82DAFBB1&index=7

    http://video.google.com/videosearch?q=nadal&hl=en&sitesearch=#q=nadal forehand&hl=en&sitesearch=

    http://www.youtube.com/watch?v=TqXmU9gEKuY&feature=related

    Here is a video of a player improving his forehand to a more advanced level by doing this.

    http://www.youtube.com/watch?v=2ho3FRWm9Pw&feature=related
     
    Last edited: Jun 20, 2008
  42. Uthree

    Uthree Rookie

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    And we shouldn't question tennis authority?


    If Braden and Yandell have similar ideas to yourself, they may wish to rethink this issue.
     
  43. Bungalo Bill

    Bungalo Bill G.O.A.T.

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    My goodness. I can't believe out of all of this, 5263 sums this up nicely. Now, only if we can get Quasar to realize his error in judgement. Doubt it. LOL!
     
  44. EricW

    EricW Professional

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    Then tell me why Bill believes even if there is no apparent CG movement, there is still significant (as opposed to negligible) linear momentum?
     
  45. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    I don't know how I got misquoted as saying that "open stance is ineffecient"....somehow you managed to get THAT out of the argument we had last night? Clearly you need to go back and re-read what I was saying. No where did I say that the open stance forehand was inefficient, I would be an idiot if I did so.

    I said, it is INEFFICIENT to use no weight transfer (which is what you're advocating, quasar and ericw) and require yourself to swing literally twice as hard to make up for the power you'd be losing by NOT using your body's weight and momentum.

    WHERE did you get that the open stance was inefficient? I literally said the above about twelve times.
     
  46. Bungalo Bill

    Bungalo Bill G.O.A.T.

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    Ahhh, twisting words again. As you have told me, "quit changing the meaning of what I am saying or what this entire thread is about!!!!"

    I do believe there is Center of Mass (COM) movement on many open stance forehands even though camera angles and the frames per second do not always make it obvious. I believe that angular momentum alone is not the only thing at work! This is why I posted my videos to provide evidence that it is okay to transfer weight forward into the ball and use angular momentum.

    I said that the tennis stroke can not be defined only using angular momentum which I believe you agreed on. I also wrote that the tennis stroke can have weight transfer in the shot even though it may not be obvious and that it happens more often then not.

    I also showed clips showing that at times, in an open stance and using angular momentum, that weight can transfer forward, backward, or remain reasonably stationary as a player rises upward.

    Did you read the tennis.com article? Did you agree with it?
     
    Last edited: Jun 20, 2008
  47. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    Get used to it, he's misquoted me at least 4 times in this thread so far.
     
  48. Bungalo Bill

    Bungalo Bill G.O.A.T.

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    I knew it!! I knew you didn't say that and I didn't even have to go back and read. This post went so far South thanks to our very own Quasar it was ridiculous. Then he had the nerve to tell us, WE don't know what we are talking about.

    The only words that were being twisted were ur words coming from Quasar and EricW. They just didnt get it.

    Only twelve? Wow, amazing how different they took that.
     
    Last edited: Jun 20, 2008
  49. GrahamIsSuper

    GrahamIsSuper Semi-Pro

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    EricW, it is clear that what YOU consider the "true" sit/lift technique is not what the technique advocates if you believe that no momentum change is required to hit the shot. It is not saying "sit", as in stop your body momentum, and lift, as in "go straight up".
     
  50. EricW

    EricW Professional

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    This is what I meant by "apparent". Even though CG movement is not always apparent it is still significant (as opposed to negligible). Is this not what you meant?
     

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