attn of tricky: how the pelvis joints work in forehand

Discussion in 'Tennis Tips/Instruction' started by albesca, May 12, 2012.

  1. albesca

    albesca Rookie

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    Hi guys. I called the attention of tricky but any comment is welcome.

    I made some considerations on what Tricky said about the loading of the hips.

    The starting points is that the rotation of the pelvis around the spinal axis doesn't mean to load the hips. This is not an obvious thing, I assure you that many players believe rotate the hips means just that.

    Rotation of trunk is over the spinal axis, but rotation of the pelvis happens over a coxo-femoral joint by turning the head of the femur with leg muscles, and throwing out the butt as maxpotapov explains in other post.


    Also, I noticed that the two hips joints work independently or together depending on the stance and the balance shifting during the shot.

    Also the orientation of the foot is not negligible importance, since it determines the maximum degree of loading of the hip joint.

    I hope to know more about this topic. To understand the hip loading can help in understanding all the legs and trunk work. Its importance, in my opinion, it's underrated.

    [​IMG]

    Thanks all
     
    Last edited: May 12, 2012
    #1
  2. albesca

    albesca Rookie

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    I've made this sequence trying to show how the hips loading-unloading axis is shifted on right hip joint ... notice how the right gluteos rotates in relation to the heel.

    [​IMG]
     
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  3. bhupaes

    bhupaes Professional

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    This is a good point. As it happens, I have a pain in the right hip in the same area you have indicated as being responsible for the hip turn, so I must be doing something right... and something wrong... :(

    As I had articulated in a previous thread (quite a while ago), I don't believe in making a huge unit turn, certainly not beyond the point where the hips tighten, since spinal rotation of the huge mass that is the torso has got to be slow, IMO. I have always put more store in pushing off with the legs than rotating the body about the spinal axis for generating pace, since pushing off is faster and more powerful.

    But the shoulders do turn without being forced, as the photographs show, and how much will depend on the physical attributes of the player. If one has flexible hips, one will turn more without explicitly being aware of it, I would think.
     
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  4. charliefedererer

    charliefedererer Legend

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    To load effectively with proper shoulder and hip coil, humans must "squat", bending at the waist and knees and ankles. (It would not be biomechanically possible to coil and stand bolt upright.)

    The leg push off straightens our ankles and knees, and as we uncoil at the hips and shoulders, the axis becomes vertical at ball strike, the position where the most effective torque is generated.

    (At other angles, the torque is proportional to the sine of the angle between vertical and the axis going down the right leg.)


    Torque http://en.wikipedia.org/wiki/Torque
     
    #4
  5. pushing_wins

    pushing_wins Hall of Fame

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    he steps forward with his left foot in the next frame?
     
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  6. albesca

    albesca Rookie

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    eh eh ...no ! He teaches "the walking step" .. but he does any walking ..:)
    he does a classical open stance footwork...

    here the next frame :

    [​IMG]
     
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  7. Chyeaah

    Chyeaah Professional

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    Why so less pixels
     
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  8. albesca

    albesca Rookie

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    Crop and high zoom from a movie still-frame, but substance i think is understandable.
     
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  9. boramiNYC

    boramiNYC Hall of Fame

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    Pelvis is both literally and figuratively central in overall balance and coordination for humans. It's directly controlled by large leg muscles, ab muscles, lower back muscles. These are muscles inside and around pelvis and increasing flexibility and strength of these muscles is directly related to ability to play tennis. So, you are right to focus on pelvis.
     
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  10. Power Player

    Power Player Talk Tennis Guru

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    Everyone is going to argue all kinds of stuff about feet and open/closed stance, so I will save you some time.

    Look at Murray above. Look at when his hips move and open up. Notice how his offhand initiates this move. Also notice how his chin is on his shoulder in pic 3.

    Copy these things and you will see how a lot of the rest falls into place.
     
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  11. albesca

    albesca Rookie

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    Thank you PP. The extension of the offhand is for me the most difficult move to learn ... really unnatural, but I am perfectly aware of its importance and its synchronism with the coiling/uncoiling of the hips.
     
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  12. boramiNYC

    boramiNYC Hall of Fame

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    The offhand does not initiate the stroke. It's pelvis turn that torques the trunk that initiates a stroke. The offhand follows the pelvis turn but leads the racquet arm. And if you think about balance between two arms the offhand thing doesn't seem so unnatural.
     
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  13. albesca

    albesca Rookie

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    Yes Borami, i've noticed it .

    If i try to extend the off-arm keeping it extended by arm and shoulder muscles ... i have a very unconfortable feeling. Instead, if i relax back and shoulder muscles and do a deep pelvis rotation, off-arm can extend more naturally and confortable.

    Arms and shouders initiate a preparation movement, waiting for the right time, pelvis initiate the loading movement as is time to hit .
     
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  14. tricky

    tricky Hall of Fame

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    Yes. If you were to turn from one of the femurs, you should be able to cause one leg to swing around the other leg, while at the same time maintaining the same distance or space between the upper thighs. If you try swinging your leg around via the core, you'll notice that the distance between your legs will change. That's one way to isolate hip rotation.

    Now, if you kept both feet stuck to the ground, you'll notice something else. Instead of the leg swinging around, your weight will move onto one of the feet. Not only that, you'll notice that your spine is moving toward the "heavier" foot. Whereas, if you were to simply turn the pelvis by using your core, your spine stays equidistant.

    Your weight transfer goes in the opposite direction of your unit turn and backswing. What this means is that, even though the pelvis turns away from the net, the spine itself is slightly moving toward the net. When you have this, only then you have hip loading. If you don't have this, you're not loading the hip regardless of how much the pelvis turns. This becomes an issue when you consider footwork.

    I usually use the one-foot drill to explain how hip rotation works in a proper stroke. But footwork is more important.

    This is dependent on footwork patterns and sequence. When the footwork "locks" the hips, the hip joints will work independently. There's no "rubber band" effect between the hips. When the footwork "opens" the hips, they work together. This is actually irrespective of stance itself. When the footwork is not good (i.e. "locked hips"), you'll see the feet very actively turning around the balls of the foot during the backswing. This is the feet now are trying to open up the hips, so that you can "uncoil" from the pelvis when you initiate the forward swing, thereby initiating late-stage hip rotation. But, done this way, you lose some timing and pure line of shot.

    What you want to look forward is increasing the base (i.e. distance between the two feet.) Turning your foot outwards in itself doesn't improve hip loading (for one thing, it can cause the hip to rotate externally as a concentric movement, which eliminates hip loading altogether.) However, the foot will be more turned out if you have a wider base. And you'll be lower to the ground.

    Having said that, this varies a lot, especially if you want your weight transfer to be primarily linear/forward or rotational/upward.
     
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  15. albesca

    albesca Rookie

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    All very clear, thank you tricky.

    What i noticed on court is that driving the upper body by the hips induces to make good use of legs as power source and feet as stable supports, and it makes a great difference in ball behaviour.. great.

    I have no doubt that hips are very involved in weight transfer and then, also in the "complexity" of the ball.
     
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  16. Austinthecity

    Austinthecity Rookie

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    What's a source of footwork patterns you recommend? Or could you elaborate a little more on footwork yourself?

    Thanks in advance.
     
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  17. tricky

    tricky Hall of Fame

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    There's some nuances with weight transfer, that you might find interesting

    Say you turn the right femur clockwise/outwards, while having both feet stay on ground. If you keep your shoulders perfectly parallel with the ground, you'll notice that your pelvis "coils", as if you were preparing your legs to shot put. If you do this a few times, you'll notice that your momentum is "rotational" and that you end uncoiling and jumping upwards.

    Now, say you turn the right femur, but this time you tilt your trunk so that the right shoulder dips. You'll notice now that your pelvis doesn't turn as much, and instead your legs will bend aggressively in one direction. If you do this a few times, you'll notice that your momentum is "linear" and you end up driving forward in the direction of the weight transfer.

    These respectively reflect a "coiling" motion and a "driving" motion. You see both types in forehands and serves, and it affects the shape of the swing. The latter (i.e. "driving motion") is more efficient at loading the shoulder (what baseball pitchers call "scalp loading.") It also leads to a more compact swing where the contact point is more out in front, and the wiping action occurs without the elbow joint drawing an arc. This is rare to see nowadays, but Federer and Safin's styles come from this.

    Each can be keyed off via visualization. If you visualize hitting a ball through two American football goal posts (| |), you'll end up using a driving motion. If you visualize hitting a ball through a soccer/footie net (=), you'll end up using a coiling motion.

    In addition, hip rotation can be facilitated by both anterior and posterior chains. However, for the open-stance FH, you want to use the posterior chain -- which means you want to load from the buttocks and hamstrings, and feel the weight come the heels of your feet.
     
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  18. dominikk1985

    dominikk1985 Legend

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    in baseball they also talk about hip coil.

    here is a video that explains it quite well (it's somewhat confused with some cheap shots because it was made in a forum discussion:D)

    http://www.youtube.com/watch?v=Ew4PXgXuzZA

    basically it is an internal rotation at the rear hip joint since the hips rotate back more than the leg which is resisting a little.
     
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  19. tricky

    tricky Hall of Fame

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    The underlying principle is that the footwork should keep the hips "open" rather than "locked." When the hips are open, you move seamlessly and your movement seamlessly transitions into the unit turn, loads your stroke and aligns to hit the ball cleanly and directionally.

    http://www.jezgreen.com/more-efficient-movement-in-tennis

    When you move with "locked" hips, there's a lot of "sideways momentum" from the waist down. When hips are "open", the sideways momentum is above the waist (i.e. the trunk.)

    So there's two general movement styles that you can try.
    Movement Pattern A:
    1) Clasp your hands together in front of your sternum, as if praying.
    2) While still holding your hands in front of your sternum, move to your right. See if you can stop on a dime without tipping over. Experiment with your movement until you can.
    3) Simulate running baseline to baseline, while still clasping your hands. Stop at different points and observe your balance.
    4) You'll notice that your trunk twists around your pelvis to lead, and that your head slightly leans toward the direction of the movement.
    5) Finally, grab a racquet and visualize yourself going through a rally. Observe what your feet and how your unit turn is affected by your movement now.

    Movement Pattern B:
    1) Put your hands in your pocket.
    2) Try moving baseline to baseline without tipping over.
    3) You'll notice that your head will stay straight up and not lean either way.
    4) Grab a racquet and visualize yourself going a rally. Observe how your unit turn is affected now.

    One movement pattern will be more suited for your FH. This varies person to person. You'll notice that you move with more sprint-like strides with A, but that your steps seem lighter or "dance-like" with B.

    If you are comfortable with the above, then try going through large figure-8 loops around the floor. This will start showing you how drop steps, step outs, shuffle steps, and carioca steps are integrated to keep the hips open.
     
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  20. tricky

    tricky Hall of Fame

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    Indeed. It's a loaded discussion, because loading the shoulder in the most efficient way possible can also lead to rotator cuff issues. The aforementioned coiling motion would correspond with the "drop and drive" motion.
     
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  21. albesca

    albesca Rookie

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    Tricky, watch the last two Tzonga forehands at second 0:38 and 0:44.

    I seem to recognize here, if I understand your explanation:

    1. first coiling motion ( flat forehand )
    2. second driving motion ( top spin forehand )

    It would appear that be a relationship with the ball spin too ...

    http://www.youtube.com/watch?v=ReIYkqazc_c
     
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  22. tricky

    tricky Hall of Fame

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    I would say both are coiling. It's rare to see a true driving motion. Safin, Federer, Nadal. One tell is that to hit the ball more in front that what's associated with the grip. If you want to experiment, try executing a FH motion while dipping your right shoulder a full foot "below" your left shoulder. See if you can still swing through the contact point.
     
    Last edited: May 17, 2012
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  23. albesca

    albesca Rookie

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    In open stance, during the uncoiling ... i noticed the left knee tends to move forward and the front foot to rise off the ground ... it seems happen a pelvis counter-rotation to counter-balance the unclockwise trunk rotation .... what do pelvis and its joints work during the uncoilng of the trunk ?

    In pic n. 5, next after the contact, see the front leg/knee/hip behaviour.
    Pelvis still in position but legs rotates around them femural axis and trunk/shoulders rotate unclockwise too ...

    I think pelvis hides many secrets about coordination and balance ....

    thanks to http://lockandrolltennis.com

    [​IMG]
    [​IMG]
     
    Last edited: May 18, 2012
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  24. tricky

    tricky Hall of Fame

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    Yes . . . but worth mentioning that you don't actually load/pivot around the front knee. The left knee "bends forward" somewhat passively, much like a serve.

    Actually . . . no. Much of the trunk rotation is actually due to the distance between the legs changing (hip adduction and abduction) and the lifting of the non-hitting hand. People presume that trunk rotation and shoulder rotation go together, but actually trunk rotation mostly facilitates the loop structure of the swing. If you were to say swing in a truly sidearm "chop" motion, you'll notice that your trunk rotation will be vastly reduced.

    What you want to look at the pics is the distance between the knees (which is associated with a stretch hip abduction.) You'll notice that, for him, as the distance increases, his trunk rotates away from the ball. One of the tells of a "coiling motion" is that distance between the knees increases during the takeback. Whereas for a driving motion, that distance closes.
     
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  25. onehandbh

    onehandbh Hall of Fame

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    Are you saying that Fed has a "driving motion"? By "driving" do you mean
    he drives through the ball more?

    What are the pros and cons of each? (though I don't quite understand
    the differences yet)

    Is my FH driving or coiling?
    What things would you change on my FH? I think I need to initial the swing
    from the legs more and let the arm lag more, but I could be wrong.
    http://www.youtube.com/watch?list=UUgtz77T-V_JqmS3dI7-EeRw&v=wBAhNP7wHiE&feature=player_detailpage
     
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  26. albesca

    albesca Rookie

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    yes, pictures 7 and 8, show clearly the division between trunk rotation and shoulders rotation

    Then, while the back leg has an active thigh internal rotation and leg extension, front leg forward flexion, thigh abduction and external rotation, would be passive. I sincerely thought that both knees, during the uncoiling, were voluntarily rotated unclockwise..

    [​IMG]

    Thigh and hip:
    a) bending;
    b) extension;
    c) abduction;
    d) adduction;
    e) internal rotation;
    f) external rotation.

    [​IMG]

    Leg:
    a) bending;
    b) extension
     
    #26

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