physics/science behind pronation

Discussion in 'Tennis Tips/Instruction' started by Chenx15, Mar 2, 2011.

  1. Chenx15

    Chenx15 Banned

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    I would like to understand the physics behind pronation. i am not sure how it makes the ball stay up and makes it spin to go down. i am doing it on my serves but for the life of me i can't understand the physics behind it. unlike ground strokes the science is pretty much straigh forward. if someone can please show me the physics behind the pronation on a serve it will be greatly appreciated. thank you.
     
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  2. dominikk1985

    dominikk1985 Legend

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    pronation does this:
    [​IMG]

    Uploaded with ImageShack.us

    Only works with a BH grip or conti grip though because it moves the rackethead around the hand and accelerates it. just try at home.
     
    Last edited: Mar 2, 2011
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  3. Chenx15

    Chenx15 Banned

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    how does it make it spin up then down. when i am just observing is slowly and just rolling the ball on the racket i can't seem to understand it.

    is there an illustration of the biomechanical movement of the forearm pronation with the racket and a tennis ball?
     
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  4. larry10s

    larry10s Hall of Fame

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    what make the ball go up and spin down has to do with bernulli principle and magnus effect and gravity
    pronation has to do with the anatomical movement of your forearm
    as you approach contact.
    if you serve with a continental grip or eastern bh grip you have to pronate some to hit the ball with the strings of the racquet
    pronation also adds to racquet head speed which causes the ball to spin faster and allow the physics of ball spin to take over.
    hope my abbreviated somewhat simplistic answer helped
     
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  5. toly

    toly Hall of Fame

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    About physics behind pronation on a serve you can read thread http://tt.tennis-warehouse.com/showthread.php?t=361610
     
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  6. larry10s

    larry10s Hall of Fame

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    brian gordon has a tremendous series of articles on the biomechanics of the serve which discusses this and more
    www.tennisplayer.net
    you will need to join for a month
    when you log in you will see biomechanic on the left click on that and you will get to his articles
     
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  7. dominikk1985

    dominikk1985 Legend

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    It's quite easy:

    with a FH grip pronation moves the edge of the racket up this creating topspin on a WW forehand.

    with a BH or conti grip on a serve it moves the face forward thus creating ball speed.
     
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  8. sureshs

    sureshs Bionic Poster

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    If you try to hit a ball with a conti grip and swing the racquet on edge, what should theoretically happen? You would hammer the ball with the frame. The fact that you don't is because of pronation.
     
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  9. Chenx15

    Chenx15 Banned

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    I understand that, the ball should be moving sideways instead of up and down. because pronation is a horizontal brush instead of vertical
     
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  10. sureshs

    sureshs Bionic Poster

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    Now imagine how you would hit a flat serve with a conti grip.
     
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  11. toly

    toly Hall of Fame

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    If you use continental grip and keep the wrist in neutral position during impact, pronation cannot produce brushing motion at all. But, wrist ulnar deviation can create topspin, sidespin etc.
     
    Last edited: Mar 6, 2011
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  12. larry10s

    larry10s Hall of Fame

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    no
    pronation is happening
    while the arm is moving in an arc
    the brush is not (rarely)horizontal or vertical its a blend of the 2
    if you have heard the serving "tip"
    hit up and out
    thats whats happening
     
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  13. LeeD

    LeeD Bionic Poster

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    Pronation has nothing to do with spin. It only adds rackethead speed, which you could spin or hit flat.
    Hold racket close to an L. Now pronate. See how much muscleLESS effort adds to rackethead speed?
     
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  14. sennoc

    sennoc Guest

    At serves? Urban legend.
     
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  15. LeeD

    LeeD Bionic Poster

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    OP is talking about serves only. He's already figured out how pronation helps in groundies.
    Hold conti grip and try serving. You gotta pronate to flatten out your shots.
     
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  16. sennoc

    sennoc Guest

    Pronation as a source of racquet's head speed at serves is NOT IMPORTANT. Dot.

    Read some scientific papers, learn how to serve properly, do not write things which are straight way to injuries.
     
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  17. GetBetterer

    GetBetterer Hall of Fame

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    I'm going with sureshs on this one. I'll post if I disagree with anything about what he says.
     
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  18. LeeD

    LeeD Bionic Poster

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    Do any of you even hit a serve you can brag about?
    Of course not, you don't pronate. Talking recent postings who say pronation doesn't add rackethead speed and those guys.
    Does pronation need active muscles? NOPE!
     
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  19. sennoc

    sennoc Guest

    LeeD, you have no idea about biomechanics of serves.

    Pronation just rotates surface of racquet's head. You have to do that intentionally, this is a result of muscles' action. But this action doesn't mean that the velocity of racquet's head is significantly larger! Physically, pronation is not important source of energy. It adds NOTHING to kick serves and no more than 10% at flat serves.
     
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  20. LeeD

    LeeD Bionic Poster

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    Yes, you of the 85 mph first serve telling someone not to pronate because it's of minor importance.
    If pronation wasn't important to adding speed, everyone would serve with and eastern forehand grip.
     
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  21. sureshs

    sureshs Bionic Poster

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    Not arguing about the speed here (don't know), but eastern FH grip will make it difficult to hit slice, topspin, and top-slice serves.
     
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  22. sureshs

    sureshs Bionic Poster

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    It is a horizontal brush, followed by a downward and away motion. You can hit a slice serve without pronation, as some of the women do from the deuce court (righties)- they seem to come from the side on their arm, and supinate.
     
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  23. Manus Domini

    Manus Domini Hall of Fame

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    aaaah no, that will hurt your wrist, trust me.

    pronation will produce a nice brushing motion, you are clueless. If you don't play the sport, please don't just bring physics in because you are overthinking it...
     
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  24. sennoc

    sennoc Guest

    Man, you are an old rude ignorant without fundamental tennis knowledge. You are talking about things you do not understand. Your "advices" can be sources of really bad injuries.

    First, you know nothing about my serves, so be nice and shut up.

    Second, pronation in the sense presented here is the action of forearm. At serves, it is not important at all.

    The sources of kinetic energy of racguet's head at serves are listed below:

    1. Shoulder velocity generated by leg drive and trunk rotation.
    2. Elbow velocity generated by upper arm, elevation and flexion.
    3. Wrist speed generated by forearm extension, forearm pronation and upper arm internal rotation.
    4. Hand flexion.

    These sources sums to ca. 70% of kinetic energy of the racquet's head. The rest is "generated" by optimal transfer of energy along the kinetic chain.

    Forearm pronation is an important part of the kinetic sequence, but it is not a source of energy, you uneducated master. It is fundamental if you want to optimally use other parts of kinetic chain as sources of energy. That's why it's so important. Without pronation of forearm you do not have access to the real sources of energy.

    The main sources of energy at serves are: shoulders (10-15%), upper arm (55-65%!!!) and hand flexion (20-30%). Source: my 30+ years of tennis experience, my knowledge of physics as a physicist and "Biomechanics and tennis", B. Elliot, Br. J. Sports Med. 2006; 40; 392-396; doi:10.1136/bjsm.2005.023150. And many other scientific sources you have never read.

    I have strong feeling, LeeD, that you have no idea about real tennis, your tennis skills are very low and this forum is a kind of substitution for you.
     
    Last edited by a moderator: Mar 2, 2011
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  25. sennoc

    sennoc Guest

    You are wrong, toly is right.
     
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  26. sureshs

    sureshs Bionic Poster

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    You are saying pronation unlocks sources of speed in the serve, LeeD is saying pronation is important for serve speed. Why is there a contradiction?
     
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  27. sennoc

    sennoc Guest

    Both things are totally different.

    If you think that pronation is a source of energy, you try to use muscles to reach the nonexisting goal. As a result, you can force your wrist (because you will experimentally discover that this action generates more energy when the racquet is not in line with your forearm).

    If you know that pronation is NOT a source of energy, you just use your forearm to rotate racquet's head. You do that just before contact with the ball, when your arm is straight, so your wrist is safe.
     
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  28. LeeD

    LeeD Bionic Poster

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    Sennoc, I have hammers from 16 oz to 26, you can borrow anytime to smash your head with... "muscle LESS effort" "active muscles, NOPE"....
    So what you say is in line to propagate argument, because you didn't read what I wrote.
    Try to understand the English language, then make yourself look silly on the internet.
     
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  29. sennoc

    sennoc Guest

    Oh. So you say I have problems with my English. Great, I know it's not my native language.

    The real problem is that YOU have problems with - your English or your tennis knowledge.

    In my opinion - your tennis knowledge is huge, but totally wrong in many important places. So hide your hammers, learn humility. The last thing we need here is an old 3.0 player as an Oracle.
     
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  30. LeeD

    LeeD Bionic Poster

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    Pronation.... you can pronate onto a flat serve, or you can pronate onto a spin serve.
    If you DON'T pronate, you will have NO rackethead speed.
    So is pronation important? Think about it.
     
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  31. sennoc

    sennoc Guest

    You make serious mistakes and you are unable to say: "yes, I was wrong".

    As I said: in my opinion you are an internet nerd with very flat tennis knowledge. Flat. With and without pronation.
     
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  32. LeeD

    LeeD Bionic Poster

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    You of the huge # of posts. Newbies know all.
     
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  33. sennoc

    sennoc Guest

    Yes, number of posts decides about tennis "knowledge".

    In your case.
     
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  34. LeeD

    LeeD Bionic Poster

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    ..and no posts means you know everything about everyone who has posted on here....
     
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  35. sennoc

    sennoc Guest

    Yes, number of posts decides about tennis "knowledge".

    In your case.
     
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  36. Manus Domini

    Manus Domini Hall of Fame

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    when I used ulnar deviation, my wrist started killing me. I base it off personal expericence, so unless I am doing something wrong with ulnar deviation and have a less-than-normal strength wrist, I stand by my experiences
     
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  37. salsainglesa

    salsainglesa Semi-Pro

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    check out this video, its about rotation

    internal rotation and pronation are analog movements. In this position rotation does help acceleration alongside a pronation followthrough, but, chech out that the position, it has to be this one... in this position the flexion of the hand actually doesnt help produce speed, it only changes the raquet head angle. If the arm is fully extended as in the amateur player example then it does accelerate the raquet, but this force wont be nearly as strong as a rotated shoulder and pronated followthrough.

    http://www.youtube.com/watch?v=lTRvxaBMh8s
     
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  38. bhupaes

    bhupaes Professional

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    Sennoc, when you say the upper arm contributes, you mean upper arm rotation as in internal shoulder rotation, right? This would move the racquet in the same way (almost) as forearm pronation, and because of this, a lot of people probably consider upper arm rotation to also be pronation. I agree, pure forearm pronation is a positioning/directing mechanism.
     
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  39. salsainglesa

    salsainglesa Semi-Pro

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    #39
  40. LeeD

    LeeD Bionic Poster

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    "Offline" is what allows pronation to ADD to the rackethead speed. So you pronate to ADD to rackethead speed, as I said.
     
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  41. sennoc

    sennoc Guest

    I agree.

    The problem is that both kind of rotations work at different parts of kinetic chain. Internal shoulder rotation is a source of energy at serves when there is L between upper arm and forearm. Pronation (of forearm) as a source of energy works when we have L between forearm and racquet. As a result, there are totally different forces acting at elbow/wrist. If you think that pronation of forearm is a source of energy, you will force your wrist to do impossible things. This is not a source of energy, this is source of injuries.

    LeeD, find another thread.
     
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  42. LeeD

    LeeD Bionic Poster

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    You are a techno weenie on the techniques of hitting a serve.
    A good server pronates, period. If he's not allowed to pronate, his serves are slow, period.
    Pronation good, not pronating BAD!
    How can you debate whether a server holds the racket off line? Of course they do, every server who can serve! You MUST know that, or shut the frick up!
     
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  43. sennoc

    sennoc Guest

    This is a good advice if you want to hit serves at full speed. But the explanation is wrong.

    Racquet not in line with forearm has nothing to do with additional energy. It is a kind of buffer - wrist is not fully extended, its position is more natural at impact, more stable and the risk of injuries is lower.

    Watch best servers, frame by frame. They pronate as late as possible, just before contact. Why? Because pronation is not important. They have to pronate because they do not want to hit the ball by the edge of the racquet. They do that as soon as possible, because they want to use as long as possible the main source of energy at serves: arm rotation.

    So, why to pronate? Can't we start with the racquet's head in hitting position? Try to do that (carefully!).

    We can't. Our wrists are too weak to deal with so huge forces. This is the real source of forearm pronation at serves: weakness of wrists.

    LeeD, could you help me, just once? Could you tell me, where can I find "Ignore" button here?
     
    Last edited by a moderator: Mar 2, 2011
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  44. salsainglesa

    salsainglesa Semi-Pro

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    Sennoc no disrispect here, but if serve was only done by the hand then that would be true, but there are more axis and levers than that.
    you know the drill, legs, hips, torso, shoulder elbow, bones of the forearm... this kinetic chan not only produces the necesary power but also the necesary alignment.

    The most effective spin serve is done accelerating the raquet through the edge, the alignment can be done with the torso... the raquet moves through the edge in reference to the body, but the torso is moving and aligns the string bed in reference to the ball... its two separate things... pronation depending on hand position and grip can add spin or pace.
     
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  45. LeeD

    LeeD Bionic Poster

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    I get it now.
    You see things from a different perspective, but the same thing!
    You see the glass as half full. Other's see it as half empty.
    You say we are weaklings and pronate to achieve rackethead speed. We say we pronate to get rackethead speed thru pronation, but don't dwell on our weakness.
    We both agree we cannot swing fast with an open face, so a closed face is necessary to get up to speed, then the opening to contact the ball square for a flat serve. That supports my argument that we should swing faster on spin second serves than we do for flat first serves because WE CAN!
    So we are different (our theories), but the same (in actual practice)!
     
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  46. Fugazi

    Fugazi Professional

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    You got that right. Sampras had tremendous pronation...
     
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  47. spacediver

    spacediver Hall of Fame

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    I'm composing a post that will explain the relationship between pronation and racquet head speed. Give me a bit of time. Am including custom rendered graphics of the biomechanics.
     
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  48. spacediver

    spacediver Hall of Fame

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    #48
  49. toly

    toly Hall of Fame

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    I posted the article (see please thread http://tt.tennis-warehouse.com/showthread.php?t=361610 ) where I tried to proof importance of the pronation. Can you give any particular negative comments about that?
     
    Last edited: Mar 3, 2011
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  50. sennoc

    sennoc Guest

    There is more, I agree. Much more, in reality. But this is a scientific fact: iternal rotation of upper arm generates 40% of energy, horizontal flexion 15-25% depending on the type of serve. Contribution of palm ulnar flexion is ca. 30% at power serves and negligible at kick serves, while ulnar flexion generates ca. 20% at kick serves and almost nothing at power serves.

    People believe in the magical role of other parts of kinetic chain because they usually watch the best servers. They (best pros) really use many many other elements, so many that they sum to important values. But what about players like Wawrinka? His kinetic chain is very short but he serves quite well. Does he use magical powers of the other universes?

    You also have to remember that kinetic energy of racquet's head is not a simple sum of energies generated at every part of kinetic chain. This energies contribute to ca. 70% of kinetic energy of the stroke. Just 70%. The rest - ca. 30% of the sum!!! - is generated by energy transfer along kinetic chain. I have a beautiful picture here from one of the scientific papers, but I can't attach the file and I'm too lazy to find a host. But I promise I'll post it here - in hours after LeeD's first video from the court ;)

    And here is the most funny part. If you want to have an access to this "additional" 30%, you have to use your kinetic chain in a way similar to a whip. The problem with amateur tennis players is that they do not use this method. But if you start working on proper serve technique, you unintentionally learn how to use better energy transfer! So, when a player starts to think about "upper arm rotation", about "pronation", he begins to move energy along kinetic chain! "Wow!" - he thinks - "that pronation is a really huge source of energy!".

    Funny, don't you think?

    Toly, give me please some time.
     
    Last edited by a moderator: Mar 3, 2011
    #50

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