The arm is not dragging by the body

Discussion in 'Tennis Tips/Instruction' started by albesca, Dec 31, 2011.

  1. albesca

    albesca Rookie

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    The arm is not dragged by the body

    Start by saying that this is only the opinion of a tennis lover, I have the pleasure to share that opinion with you.

    I think that pushing more with legs or turning fast the trunk will not help on producing more arm speed.

    The speed of the arm is produced by the arm.

    The important thing is to understand the body posture significantly affects the ability to swing fast the arm.

    Searching the perfect distance and taking the perfect posture at a certain time, here is what the body does. During the search for the ball, the positioning of the feet, the body coiling ...the arm doesn't exist. But when it's time to hit the arm becomes the master, and the body simply has to follow his will.

    Happy new year to all
    Al
     
    Last edited: Dec 31, 2011
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  2. papa

    papa Hall of Fame

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    Well, first of all we're interested in racquet "head" speed and its not just generated by the arm - far from it. Most lower level player use way too much arm in playing this sport and as a result either end up with arm/shoulder injuries, are totally inconsistent, can't generate much pace, etc. When just the arm is involved, there is excessive lateral movement into the ball as compared with rotation. When just lateral movement is involved the stroke is very sluggish and just won't hold up.

    So, in my opinion, you have this a little bit backwards.
     
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  3. albesca

    albesca Rookie

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    Tank you Papa for ur opinion. I don't talk about all the stroke .. i'm talking only about the forward swing. Before, body works hard for positioning and loading... but as the forward swing starts I think the body must reduce its role about to do the correct footwork and upper body would have to uncoils following the arm, and not driving it.
     
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  4. rkelley

    rkelley Hall of Fame

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    Well, I would advise the opposite of what you're saying here. The legs, trunk, and shoulders provide the power. They start the swing. The arms and the racquet whip around and the head of the racquet whips into the ball. The arms and wrist do some fine tuning as to exactly when the whip is cracked and exactly where the racquet head goes - that's why you keep your eye on the ball through impact - but the legs, trunk, and shoulders start the swing and provide the power.
     
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  5. spacediver

    spacediver Hall of Fame

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    Just because the arm is swinging around joint X doesn't mean that the momentum is generated at joint X.

    Think of a whip - the tip of the whip breaks the speed of sound, but all the momentum is generated in the heavy handle.
     
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  6. toly

    toly Hall of Fame

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    When we rotate trunk with acceleration, IMO the passive arm will never whip around the body. Thus, the arm and its parts should be active, or we should slow down trunk acceleration. Does it make any sense?
    If trunk doesn’t rotate at all, the arm by itself still can rotate around shoulder joint etc. I believe that good athlete can hit 100 mph FH without trunk rotation, by using just active arm motions. He will never be able to do that with passive arm relying on whip effect. I tried it many times and always got pathetic FH.:)
     
    Last edited: Dec 31, 2011
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  7. maxpotapov

    maxpotapov Hall of Fame

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    My experience, pretty much. But all those exercises helped me to improve my body positioning, posture, core and back muscles etc.
    Now I simply add arm/wrist/fingers action to turn racquet head around, once I got fundamentals (lower/upper body) right.

    It is simple physics: during body rotation centrifugal forces pull racquet forward/away, not around the body. There is no physical way racquet shaft will bump against your left shoulder on follow through if your hitting arm is all passive during upper body rotation.
     
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  8. albesca

    albesca Rookie

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    Obiouvsly there are many ways to hit the ball on the other side of the court. What I believe is that it is impossible or so to produce an heavy ball without producing an high raquet head speed... and by dragging the arm whit the trunk i don't believe it is reliable.

    Sure, the more fast we want to swing the arm, the more we have to be able to rotate the trunk fast, that mean great body and legs work .. but not the opposite.

    Ironically, a too fast trunk rotation can disturb the swinging of the arm instead to help it on swinging fast.

    Agree Toly, exactly what I would say.


    Absolutely agree Max.
     
    Last edited: Jan 1, 2012
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  9. rkelley

    rkelley Hall of Fame

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    When folks talk about "passive arm" it's not to say the muscles in the chest, arm and wrist are not being used, but the majority of the power is coming from the core rotation that starts with the legs, then through the hips and shoulders. Assuming that the arm is still attached to the shoulder at this point it has to whip around the body.

    Check out this video, 0:36. This is what's happening: http://www.youtube.com/watch?v=EMNtq...eature=related

    And here's a video that shows the whipping action in the full forehand stroke: http://www.youtube.com/watch?v=EMNtq393tvo&feature=related

    If you try to hit 100 mph forehands with just your arms, assuming that's even possible, I think you'll tear your shoulder apart pretty quickly.
     
    Last edited: Jan 1, 2012
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  10. rkelley

    rkelley Hall of Fame

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    toly, maxpotapov, and albesca, here are some video links to pro forehands.

    Here's Fed's forehand with some good analysis: http://www.youtube.com/watch?v=ydMHJGpypQE

    Here's Djokovic's forehand: http://www.youtube.com/watch?v=y8AJYfkJ4hc&feature=related
    No analysis on this one but you can see (or at least I can) the same action of the shoulders whipping the arm around. Note that Djokovic is using a Western grip.

    And then there are the two Lock and Roll videos that explain the concept and teach the forehand:
    http://www.youtube.com/watch?v=Wwg9DB8S8a8
    http://www.youtube.com/watch?v=EMNtq393tvo&feature=related

    Give this stuff a try.
     
    Last edited: Jan 4, 2012
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  11. 5263

    5263 G.O.A.T.

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    IMO you and the OP make some good points here and that maybe the
    body does more to position the arm so that then the arm can create the
    acceleration of the racket. Oscar often talks of how much the biceps are
    involved.
     
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  12. papa

    papa Hall of Fame

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    Well, this is certainly how I see this whole process. I know, and frequently see, other attempts at hitting the forehand but I just don't happen to agree with them.

    I know for example of a guy that can absolutely smack the ball and he stays on the rear foot throughout the stroke. For him, "maybe" it works to a degree but I honestly believe that as good as he presently is (I'm taking forehand) he would be that much better if he used the example provided by rkelley. Can he hit the ball with more pace than me - yeah, probably but I'd win hands down when it comes to consistency and placement. He isn't all arm by the way and is able to generate wicked racquet head speed coming across the body which I like - I just like more weight transfer.

    I know some don't care to move away from their all arm approach and I realize that for them, it might work. Many have learned this game when racquet/string technology didn't play such a significant role - that's just not the case anymore.
     
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  13. rkelley

    rkelley Hall of Fame

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    I've learned this whole modern forehand "thing" and letting my arm whip around in the last year. It's been an adventure.

    I'll say that for me it's taken a fair number of hours of practice to get the feel of it. At first, when I did it correctly, it felt great, but other times I'd miss time it. I wasn't feeling the arm whip and I wasn't getting any power. Some days I'd really have it, and then I'd struggle the next time out. I kept at it, practiced on the wall, and now it's pretty automatic.

    Relative to my old school forehand the two biggest improvements are greater spin and consistently hitting with more power - and they're linked. I can get a lot more topspin than I used to be able to. This is critical for getting shots to land in that would otherwise go out. I can also hit with greater power in all positions on the court. When I have to I can just stay in a totally open stance, reach across with my left arm and take the racquet back, and rip a pretty decent forehand. But without the topspin all that extra power would launch balls long.

    As I've gotten better at hitting this forehand it really cool how much racquet head speed I can get without really swinging that hard. The racquet head just naturally whips around. I can control the swing path so that I can control the amount of topspin verses hitting through the ball.
     
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  14. toly

    toly Hall of Fame

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    This is a very bold statement. You are a Mechanical Engineer. Can you prove your claims using the scientific approach? Please feel free to employ any formula, the laws of physics, math, etc.

    Happy New Year!:)
     
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  15. albesca

    albesca Rookie

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    No doubt, agree with this point 100 percent. Only I think the trunk doesn't drag..

    Dragging the arm, trying to maintain a constant angle at the elbow joint, results in an isometric or so biceps action that stiffens the swing.

    This is ok if I have to manage an hard ball .. but I'd clearly divides the cases where our priority is to accelerate the racket head from where our priority is to maintain a stable head of the racket, and this depends, at first, on the speed of the incoming ball.

    By me seems to have great raq. head acceleration, the elbow needs some independence form the shoulder joint.. this mean, at the end, to have active biceps during the forward swing.

    I don't know so much about the Oscar Wegner method, only here I read something, but agree , biceps , forearm pronator and fingers tendons .. imho have the control of the raquet head acceleration.
     
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  16. ho

    ho Semi-Pro

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    1/Leg and core rotation provide the major power in rotational movement
    2/Arm whip around shoulder provide the most racket speed in linear movement.
    (1) provide speed if you hit with body and arm as one unit. Not the racket speed that give you the ball speed, but the compression of the ball against a solid object self create the ball speed.
    (2) provide racket speed but their is only the arm weight behind the racket, law of physic on colliding will indicate that ball speed will not always as much as (1) particular when ball coming in great speed.

    The best way is to combine both:
    You hit with arm and body as one unit
    Right by the time after contact, whip out your arm forward for more speed and spin.
    Saying it is easy, but doing it need great timing and accuracy:
    You extend your arm out by:
    1/ keeping your arm loose
    2/ time the push out of your arm by using your left hand: drop to the chest early will launch your right shoulder at the right moment.
     
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  17. rkelley

    rkelley Hall of Fame

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    Hi Toly. I don't think of this statement as being bold or controversial. Go to just about any instruction site and you'll see something similar said. It's completely consistent with what I see when I watch pros and high level players hit, and it's completely consistent with my own personal experience.

    Meaning no disrespect, but it just seems really obvious to me. Yes, I am a mechanical engineer. As an engineer I'd tell you that muscles groups in your legs and core are far stronger than the muscles in your shoulder alone. Wouldn't it make sense to utilize those stronger muscle groups in generating power? An analytical analysis would need to take into account.

    Seriously, just go out and hit some balls. Can you hit it harder when you use just your arm, or when you use your legs and body too? Do what works for you and have fun.
     
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  18. toly

    toly Hall of Fame

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    It’s true that leg and core rotation provide the major power, but with very low efficiency, from ball/racquet speed point of view. Most of this energy is wasted for rotation of 200 pounds and just a little bit is going to the ball.

    If arm is passive and moves like the whip, it cannot produce decent linear racquet speed.

    It cannot provide a lot of speed because body and arm as one unit has very big mass. Thus, this unit would be relatively slow, compare with elbow or wrist motions.

    The ball speed approximately is

    Vballspeed = Vracquetspeed x (1 +K), (1)

    Where K is coefficient of restitution.

    If the racket has speed 80 mph, K is around 0.3. So, the compression of the ball cannot be the main factor. According to formula (1), the racquet speed is the main factor of the ball speed.


    See please my posts: http://tt.tennis-warehouse.com/showthread.php?p=5892760#post5892760, http://tt.tennis-warehouse.com/showthread.php?p=5895380#post5895380
     
    Last edited: Jan 3, 2012
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  19. DavaiMarat

    DavaiMarat Professional

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    You are partly right about this accessment but also partly wrong. I would have to agree with papa, the body plays an importantly role in coiling, the body also uncoils as you bring the racquet out of the slot and forward unto the ball. If you look from the slot and contact the arm doesn't really move that much save for the forearm. As you continue into the forward swing the body stops rotation to allow the arm to 'snap' around the shoulder axis finishing the 2nd to last part of the kinetic chain (wrist being the last). Not very often will you find players extending the fully 180 degrees. Djokovic may be an exception to this rule.

    So yes the body rotation stops acts like a fulcrum against the arm but it's the body who initializes the forward swing.

    Read the article 'The arms swings the least' at tennisone.com...you will grasp the concept.

    I like to think of this way. The arm lifts, the body hits!
     
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  20. toly

    toly Hall of Fame

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    If arm and wrist are being used actively, there is no reason to talk about the whip. In whip, only handle is active and the rest of whip must be passive. IMO, you are using wrong terminology and got me completely confused.:???:
     
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  21. rkelley

    rkelley Hall of Fame

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    You're looking at this in too much of a black and white fashion. The arm is whipped around. The terminology is correct. Is it completely passive? Of course not. You're taking the analogy too far. You certainly use the arm muscles, but the salient point is that most of the power comes from the legs and the core whipping the arm around, not from the arm muscles contracting without the loading from the legs and core.
     
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  22. DavaiMarat

    DavaiMarat Professional

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    Rudimentary physics dictate that one body that is carry by other will inherit it's velocity in addition to any velocity it generates by itself. For example if subway and I run from the from to the back at 15km an hour and the train is moving 60km. I have a velocity of 75 km.

    This is the same for rotational acceleration, if my body is turning and my arm is turning as well, the arm will pick up the rotational speed as well as it's own rotation speed, but in this case I believe it's a exponential in gain unlike the linear example I gave you before (w^2). So it's hard to argue that the body doesn't contribute at all let alone not playing a major role in power and rhs.
     
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  23. albesca

    albesca Rookie

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    Absolutely agree, the arm do nothing without the loading from the legs and core.

    But i still on my idea the trunk doesn't have volountary to drag. It musn't rotate as fast as possible.. legs haven't to work in that way during the forward swing.
    The shoulder joint have to move at exactly speed needed by the arm... not less... but not more... because the dragging doesn't add power, but by me, destroy the arm coordination.
     
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  24. ho

    ho Semi-Pro

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    As I said, physic law of collision:
    m x v = m1 x v1 ( m is mass and v is speed)
    1/Ball speed depend on physic law of collision
    2/Ball speed depend on how much it is compressed and bounce out by itself and to and advance level, it depends on the prolongation of contact time.
    Tell me you comprehend these, ( not disrespect at all, we need to be on the same page) then i continue to the linear energy (whip)
     
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  25. ho

    ho Semi-Pro

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    Drive your car, hit the brake, car stop, you feel like you have an unknown energy push you forward. that energy is Kinetic Energy.

    When you drag your arm behind, near contact body rotation slow down, the Kinetic Energy will push your arm forward if you keep a loose arm. Kinetic Energy need time to build up, therefore the idea of dragging emerges as an ingredient in Pull stroke: You pull the racket forward as Nick B. describe in his tape.
     
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  26. ho

    ho Semi-Pro

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    The body do contribute to the the speed of your arm. But the main power of your arm is not by itself, but by the fact that body slow down:
    Run 25m/h on the train with 50m/h your speed is absolutely 75m/h. Now if the train suddenly stop: You will get kill by your enormous speed instantly.
     
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  27. toly

    toly Hall of Fame

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    I answered on all your claims in post #18, except the idea “… the prolongation of contact time”.
    jumpulse.com tried very hard to sell this idea, but without any success. IMO this is nonsense, absurd etc. Even Oscar Wegner quit taking about that.:)
     
    Last edited: Jan 3, 2012
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  28. toly

    toly Hall of Fame

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    Your statement contradicts with Bruce Elliott measured data http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577481/table/tbl2/

    Topspin forehand (forward direction)
    Approximate contributions to impact racquet velocity (%)

    Shoulder 15
    Upper arm - Horizontal flexion 25
    Upper arm - Internal rotation 40
    Hand 20

    IMO, shoulder means: power from legs, core, and etc.
    This power produces just 15% of the racket velocity.
    The arm and its parts create 85%.
    Thus, the arm actions are much much much more important than legs, core, and etc actions!!!:)
     
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  29. user92626

    user92626 Legend

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    Killed by enormous speed?

    What kind of logics is this?


    If you got killed from that, it would likely be from slamming your face on the ground or something similar.
     
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  30. albesca

    albesca Rookie

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    This i what i feel Toly.. without using biceps and forearm is impossible or so to transmit great amount of energy on the ball ... but this your last one is an exaggeration : "Thus, the arm actions are much much much more important than legs, core, and etc actions!!!"

    The kinetic chain energy as a sequential sum of its segments energy, it's a myth. Each segment affect the operation of the other, don't add, so imho, to produce its 85%, the arm absolutely needs that 15% body work. Therefore, by me, despite their contribution in terms of energy is vastly different, their importance is the same.

    What I do not agree is keep repeating that the legs and trunk are the mainly responsible for power. This causes players to forget the arm and lost years to strengthen legs and abdomen without seeing concrete results in terms of power ( but many other advantages..)... until one day, by accident, they decide to put a lot of attention and a lot of energy also in their arm.
     
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  31. SystemicAnomaly

    SystemicAnomaly G.O.A.T.

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    ^ The role of the biceps is not as important as you seem to think. I do not see any forceful use of the biceps until late in the follow-thru. But I do agree that the role of the body -- legs, hip rotation, torso rotation -- is important.

    Not certain that I agree with your assessment of th kinetic chain. The various links in the chain accumulate and transfer energy to the next link in the chain. In the study referenced by toly (above), Brian Elliot states, "In strokes where power is required (such as the service and groundstrokes), a number of body segments must be coordinated in such a way that a high racquet speed is generated at impact."

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577481/

    I don't believe that most players are in any real danger of not developing sufficient arm strength for tennis. Exercises to protect the shoulder/rotator group should be perfromed, but developing a lot of arm strength is not really all that crucial.
    .
     
    Last edited: Jan 4, 2012
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  32. Limpinhitter

    Limpinhitter Legend

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    I think the L&R guy understands and teaches modern groundstrokes as well as anyone I've seen online.

    PS: Your second link to the L&R guy is bad. Is this what you were looking for? http://www.youtube.com/watch?v=EMNtq393tvo&feature=related
     
    Last edited: Jan 4, 2012
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  33. rkelley

    rkelley Hall of Fame

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    Thanks for the link fix. I'll try to correct the original post.
     
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  34. albesca

    albesca Rookie

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    I don't see so much difference.

    Brian Elliot says "In strokes where power is required (such as the service and groundstrokes), a number of body segments must be coordinated in such a way that a high racquet speed is generated at impact."

    Agree .. and It's exactly what i would say here:
    "The kinetic chain energy as a sequential sum of its segments energy, it's a myth. Each segment affect the operation of the other, don't add"

    You have right, i forgotten all muscles involved around the shoulder joint.

    If the technique is correct, the swing itself is a constant practice for arm muscles. Surely we would develop the speed of the arm, and not strength.

    Thank you Sys
    Ciao
    Al
     
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  35. DavaiMarat

    DavaiMarat Professional

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    I agree with this post.
     
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  36. toly

    toly Hall of Fame

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    I disagree with this statement.
    Let’s assume we rotate torso around the spine with fixed passive straight arm. Since the arm is connected to the shoulder, it inevitably begins moving and therefore it gains kinetic energy. Thus, some segments of the body can add energy to other ones. But, I think this is obvious and you certainly understand that.:)
     
    Last edited: Jan 9, 2012
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  37. toly

    toly Hall of Fame

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    Can you provide any serious proof?

    I think that 15% contribution to the racquet speed is not very important for the reason that we have to waste a lot of energy to create fast rotation of 130 - 200 pounds body. IMO it is better first to concentrate on arm actions and then on the body. The arm is much more important. In tennis everything is important, however with varying degrees of importance.
     
    Last edited: Jan 4, 2012
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  38. maxpotapov

    maxpotapov Hall of Fame

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    As I understood Albesca, it's not just arithmetic sum, but there's a progression in how parts align and interact to create optimal conditions for fastest racquet acceleration at the point of impact.

    I would also argue, that even if PROPER coordination/rotation of lower/upper body contributes only 15% to the racquet speed, LACK THEREOF might cause a 40% slow down.
     
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  39. Limpinhitter

    Limpinhitter Legend

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    I think what rKelley is saying, which I concur with, is that Bruce Elliot's data does not withstand the scrutiny of practical experience to the contrary. "The proof of the pudding is in the eating," as they say.
     
    Last edited: Jan 4, 2012
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  40. Limpinhitter

    Limpinhitter Legend

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    Ahhh! That's another issue. Your original premise was that UBR played no role in racquet speed. If you rotate as fast as possible, the connection between upper body rotation and arm swing becomes disconnected, because the UBR has completed before the arm swing has begun, and any benefit is lost. There is, however, an optimum speed at which the contribution of UBR to arm swing is maximized. I don't know how to calculate that value, which would be of no practical benefit anyway. But, I know it when I feel it, which is much more useful and practical.
     
    Last edited: Jan 4, 2012
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  41. ho

    ho Semi-Pro

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    I'm sorry, if you slam on something
     
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  42. ho

    ho Semi-Pro

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    Ball is a soft object, on impact it deformed, the harder you hit, the more it deformed, the more it deformed, the more it stay on the string bed, the more it stay on string bed, the more it bounce out.
    Oscar is a tennis coach, he is not a scientist.
    Just hit the heck out of the ball, arm and body as one unit, you will have such an easy time on the court.
     
    Last edited: Jan 4, 2012
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  43. toly

    toly Hall of Fame

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    Yes, I agree with you.

    The problem is that we don’t know ideal procedure on how to hit FH. After 30 years from now, current FH technique probably would be ridiculous. But, at least we should try to understand what is really very important and what is not.

    For example, Lock&Roll coach emphasizes too much importance of the hips and body rotation. But, when he demonstrates FH, his arm and its parts (including wrist) are very active. That’s why I dislike his monkey’s drum idea. IMO he puts wrong accents in his explanations.
     
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  44. Dellon

    Dellon New User

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  45. Dellon

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  46. Dellon

    Dellon New User

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    to me this is the ultimate position in tennis with your upper body facing the net ... when I hit a forehand I always think I'm hitting it with my chest and when I do that everyhting else works perfectly.

    [​IMG]
     
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  47. Dellon

    Dellon New User

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    how do I attach a picture?
     
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  48. Dellon

    Dellon New User

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    this is what I'm thinking that I am when I rotate my body and hit a forehand ...teh top handle is my shoulders and chest) ... just imagine it has a spring at the bottom ... you twist it to the right and then release it ... no hip rotation no other things ... they happen naturally as they all conect you to the ground

    http://www.advdesigns.com/ro14insptdr.html
     
    #48
  49. toly

    toly Hall of Fame

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    The harder we hit the ball, the more it is deformed and damaged. The damage of the ball is essential.
    If we hit ball with racquet speed 1 mph, coefficient of restitution (if I remember correctly) will be around 70%. If racquet speed is 80 mph, this coefficient is just 30%. Thus, scientific data disagree with your statement.

    If we rotate fixed passive arm and body as one unit, we will produce around 15% of the possible maximum of the racquet speed. See please Elliot data.
     
    #49
  50. maxpotapov

    maxpotapov Hall of Fame

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    That's most likely due to assumption, that novice/recreational players use their arm only, and hips/body rotation is counter intuitive and thus must be overemphasized.

    I personally think it's a good way to start, as developing proper fundamentals is difficult (counter intuitive, energy inefficient) yet essential. But once body starts moving and working, it's time to explore those 85% that accelerate racquet head through the contact point.
     
    #50

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