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Thread: How Biomechanists Define Movements

  1. #151
    Jeffy: your views on supination have been made clear. Tapio has made his views clear on supination AND PF. So, just to be clear, what is your view on PF then? Specifically: Is it active or passive?

  2. #152
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    Quote Originally Posted by golfdad View Post
    Hello Footwedge, I must confess I did not follow the beginning part of this thread carefully because it was a bit confusing to me, over terminology differences or different scenarios that may actually be valid due to compensations or combinations of muscle action. There is a bit of guess what I am really saying there

    I don't play golf and study this stuff deeply, but my feeling is that assuming we can arrive at pure flexion, on that table (which is difficult to do if the club is horizontally in line, the wrist is quite severely ulnar deviated, but if the club is vertical to the table, the wrist can be in flexion more comfortably) then flexion and extension only affect loft, and not face alignment. I suspect ulnar and radial deviation, which can creep into the picture quite easily, will affect face alignment to some degree due to some translational shifting effect. I believe supination and pronation will drastically affect alignment with most certainty. On top of those, if the shoulder joint allows some degree of internal and external rotation, the permutation goes wilder.

    So, given one moment in time at a particular point of the swing arc, we can guesstimate the major, noticeable actions, but some subtler one may escape our attention or calculation. Since our body is quite dynamic in motion, it is inconceivable that some parts can be shut down absolutely.

    Jeffy, it will be a fun exercise to provide a sequential map of Sadlowski's swing at the "P"s in terms of those terms used here. The SuperHuman Swing Project

    You don't have to have the wrist in a severe ulnar deviation position it can be slightly radially deviated and the face will still not rotate but the shaft will swing away from the the target line or to the right of the body.

  3. #153
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    Quote Originally Posted by jaja View Post
    Jeffy: your views on supination have been made clear. Tapio has made his views clear on supination AND PF. So, just to be clear, what is your view on PF then? Specifically: Is it active or passive?

    I never thought about it specifically. What I have thought about is whether or not there are certain "natural" movements which would speed learning golf or produce a superior swing, as some methods and instructors claim. I concluded that there are, in fact, very, very few movements that don't need to be learned by humans post-birth. The only "natural" or "instinctive" movements I can recall from my two boys as new-borns were sucking, grasping with the hand, swallowing, activity at the other end, blinking and crying. After that, every movement and action had to be learned.

    So, I'm inclined to believe that going from DF to PF in mid-downswing has to learned, just like practically everything else, although the swinging club's desire to stay in-plane probably aids that learning.


    Jeff

  4. #154
    Golfdad: thanks for taking the time to make the video.

    Whilst you MAY have RD'ed to some miniscule degree it was clear that your ability to RD in the PF'ed position was very restricted and your attempt to further RD resulted in supination BECAUSE the wirst "locked". The reverse situation which you demonstrated (RD'ed first then PF'ed) resulted in a different end position which you inaccurately described as the same.

    But the long and short of my point was that the movements (PF/DF, pronation/supination, RD/UD) are INTERCONNECTED. Your video proved that, although you claimed the opposite

  5. #155
    jaja, it was fun making the videos, to test out some of my thoughts.

    You have raised an interesting point about my arriving at a wrong description that RD then PF ends up in the same location as PF then RD. I disagree with your assertion and since I don't know your background in this discipline, I will just leave it as such. But I think it will be informative if you can consult with some validated pros in this area, such as qualified physicians or PTs or some other experts that I have not thought of.

    Before I let you run off to the experts, here is a question: assuming you are going to draw a circle with your stretched out index finger (dipped with ink) by purely using the wrist action, does a counterclockwise circular rotation produce a different circle (size or shape or other parameters) from one done by a clockwise circular rotation? If you are not sure, ask the experts this question as well.

    I believe I have repeatedly stated that the issues are multi-factorial and to say that I have claimed the opposite seems a bit reaching
    Last edited by Al Ku; March 1st, 2012 at 07:03 PM.

  6. #156
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    Quote Originally Posted by birlyshirly View Post
    Jeff - remember Tapio's PF demonstration, and Kelvin's immediate response that the lines on Tapios forearm indicated supination, even although Tapio felt there was none?

    I can't help but wonder whether, if you reshot the first pair of those photos with a visible line up the inside of your left forearm, we wouldn't see a small amount of left forearm pronation when you lay the shaft down.
    Odd question. The point of the demonstration is to show that PFing the left wrist does not, as Tapio claims, automatically create counter-clockwise forearm rotation (what everyone but Tapio calls supination). Anyhow, if I my forearm did respond to PFing by rotating clockwise (what everyone but Tapio calls pronation), I guess that would just prove Tapio doubly wrong!

    Here's the video.



    At this point I think you ought to get your own video camera (I've been just using my iPhone for these) and post your own demonstrations if you think I've done something wrong. As you will recall, our rule reads in part:

    And that includes criticisms of analyses that others have posted: if you think someone has done an analysis incorrectly, show us how to do it right! We don't need a peanut gallery here. With V1 software only costing $40, YouTube overwhelmed with great swing videos, and free photo hosting on Photobucket and other hosting sites, there are no excuses! Put up or shut up!

    Also, in the second of that first pair of photos, you can see the gap between your left hand and the edge of the filing cabinet narrow. Would pure, isolated PF do that?
    Another odd question. Anyway, I don't think so; my arms are wandering a bit because they aren't braced. Again, check the video and, if you think I've done something wrong, show us how to do it right.


    Jeff

  7. #157
    TeeAce Guest
    Quote Originally Posted by footwedge View Post
    @ Golfdad Nice video, now to complicate matters, when your forearm is on the desk and you are doing P.F. if you had a club in your hand and inline horizontally with the desktop would the face of the club and the shaft rotate axially just doing pure P.F.? If you then stood the club up verticle but kept your forearm on the desktop (of course you would have to adjust slightly so the butt end is free from hitting the desk surface) and did pure P.F. would the face then rotate as Tapio showed?

    You see it all depends when and how you do the p.f. and where the clubshaft is in relation to the whole swing motion. You can get a bowed wrist without twisting the face .
    Footwedge, that's not possible unless you have your shaft and fingers parallel. In every other case PF will rotate the shaft and that's pure and simple geometry. There is no "how you do PF, there is just one way to do it in neutral position

    For example in those Jeffys PF videos, he doesn't make PF but also pronation and that way those two moves cancel each others.

  8. #158
    Quote Originally Posted by TeeAce View Post
    Footwedge, that's not possible unless you have your shaft and fingers parallel. In every other case PF will rotate the shaft and that's pure and simple geometry. There is no "how you do PF, there is just one way to do it in neutral position

    For example in those Jeffys PF videos, he doesn't make PF but also pronation and that way those two moves cancel each others.
    It ( pure PF in isolation ) will not rotate the shaft when done in its correct plane of the hand , which is changing with every grip type

    * Marginal movements: radial deviation (abduction, movement towards the thumb) and ulnar deviation (adduction, movement towards the little finger). These movements take place about a dorsopalmar axis (back to front) at the radiocarpal and midcarpal joints passing through the capitate bone.
    o Radial abduction: extensor carpi radialis longus, abductor pollicis longus, extensor pollicis longus, flexor carpi radialis, flexor pollicis longus
    o Ulnar abduction: extensor carpi ulnaris, flexor carpi ulnaris, extensor digitorum, extensor digiti minimi
    * Movements in the plane of the hand: flexion (palmar flexion, tilting towards the palm) and extension (dorsiflexion, tilting towards the back of the hand). These movements take place through a transverse axis passing through the capitate bone. Palmar flexion is the most powerful of these movements because the flexors, especially the finger flexors, are considerably stronger than the extensors.
    o Extension: extensor digitorum, extensor carpi radialis longus, extensor carpi radialis brevis, extensor indicis, extensor pollicis longus, extensor digiti minimi
    o Palmar flexion: flexor digitorum superficialis, flexor digitorum profundus, flexor carpi ulnaris, flexor pollicis longus, flexor carpi radialis, abductor pollicis longus
    * Intermediate or combined movements

    However, movements at the wrist can not be properly described without including movements in the distal radioulnar joint in which the rotary actions of supination and pronation occur and this joint is therefore normally regarded as part of the wrist. [14]
    See also

    * Distal radius fracture
    * Brunelli Procedure, related to instability in the wrist
    * Knuckle-walking, a kind of quadrupedal locomotion involving wrist bone specialization
    * Wristlocks use movement extremes of the wrist for martial applications.

    Notes

    1. ^ Behnke 2006, p 76. "The wrist contains eight bones, roughly aligned in two rows, known as the carpal bones."
    2. ^ a b Moore 2006, p 485. "The wrist (carpus), the proximal segment of the hand, is a complex of eight carpal bones. The carpus articulates proximally with the forearm at the wrist joint and distally with the five metacarpals. The joints formed by the carpus include the wrist (radiocarpal joint), intercarpal, carpometacarpal and intermetacarpal joints. Augmenting movement at the wrist joint, the rows of carpals glide on each other [...] "
    3. ^ Behnke 2006, p 77. "With the large number of bones composing the wrist (ulna, radius, eight carpas, and five metacarpals), it makes sense that there are many, many joints that make up the structure known as the wrist."
    4. ^ Baratz 1999, p 391. "The wrist joint is composed of not only the radiocarpal and distal radioulnar joints but also the intercarpal articulations."
    5. ^ "Fractures, Wrist". eMedicine, Medscape. http://emedicine.medscape.com/article/828746-overview. Retrieved August 2009. "Fractures of the distal radius, ulna, or both account for approximately three quarters of bony injuries of the wrist."
    6. ^ "Hand Etymology". American Society for Surgery of the Hand. http://www.eatonhand.com/clf/clf522.htm. Retrieved August 2009.
    7. ^ Isenberg 2004, p 87
    8. ^ Platzer 2004, p 122
    9. ^ a b Platzer 2004, p 130
    10. ^ Platzer 2004, pp 126-129
    11. ^ Saladin, 2003, pp 361, 365
    12. ^ Platzer 2004, p 132
    13. ^ Platzer 2004, p 172
    14. ^ Kingston 2000, pp 126-127

    References

    * Baratz, Mark; Watson, Anthony D.; Imbriglia, Joseph E. (1999). Orthopaedic surgery: the essentials. Thieme. ISBN 0865777799. http://books.google.com/books?id=TbxYM_Ts-3YC&pg=PA391.
    * Behnke, Robert S. (2006). Kinetic anatomy. Human Kinetics. ISBN 0736059091. http://books.google.com/books?id=dbVv5OhJimcC&pg=PA78.
    * Isenberg, David Alan; Maddison, Peter; Woo, Patricia (2004). Oxford textbook of rheumatology. Oxford University Press. ISBN 0198509480. http://books.google.com/books?id=m7GOyN5wYVAC&pg=PA87.
    * Kingston, Bernard (2000). Understanding joints: a practical guide to their structure and function. Nelson Thornes. ISBN 0748753990. http://books.google.com/books?id=6DH97qvthj4C.
    * Moore, Keith L.; Agur, A. M. R. (2006). Essential clinical anatomy. Lippincott Williams & Wilkins. ISBN 078176274X. http://books.google.com/books?id=Xz8...C&pg=RA1-PA485.
    * Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol. 1: Locomotor System (5th ed.). Thieme. ISBN 3-13-533305-1.
    * Saladin, Kenneth S. (2003). Anatomy & Physiology: The Unity of Form and Function. McGraw-Hill.

    External links
    Wikimedia Commons has media related to: Wrist
    Look up wrist in Wiktionary, the free dictionary.

    * Wrist ligaments at upenn.edu
    * wrist at eMedicine Dictionary
    * wrist+joint at eMedicine Dictionary
    * Hand kinesiology at UK bone/wrist.html


    Read more: http://www.answers.com/topic/wrist-1#ixzz1nwxHakHV

  9. #159
    Quote Originally Posted by TeeAce View Post
    Footwedge, that's not possible unless you have your shaft and fingers parallel. In every other case PF will rotate the shaft and that's pure and simple geometry. There is no "how you do PF, there is just one way to do it in neutral position

    For example in those Jeffys PF videos, he doesn't make PF but also pronation and that way those two moves cancel each others.
    I try to understand as much as what you guys are trying to get to, but I fail to see the reason of using the word like "rotate" in reference to the shaft and in fact I fail to see the reason of paying attention to the shaft which does not contact the ball, hopefully. I believe what should be kept in mind is the club face and the ongoing question is whether the club face has changed in terms of loft or alignment or even both.

    In reference to Jeffy's wrist flexion demo, I don't see he simultaneously does both pure flexion and pronation as suggested by teeace (vs truly doing both simultaneously). This distinction is crucial.

    Jeffy put his left upper limb in shoulder adduction, shoulder flexion, shoulder internal rotation and some degree of pronation so that the hand holding the grip is more or less in front of pant pocket/zipper area. THEN, he performed wrist flexion, which is not canceled by anything else, certainly not by pronation. In other words, the wrist flexion performed in anatomical neutral elbow position is as PURE as the wrist flexion performed in elbow pronation. In either case, while the wrist flexion occurs, there is zero degree of elbow input or interference. Wrist joint is dynamic, doing flexion while the elbow joint is static, staying put in whatever position it is in.

    An unsightly analogy will be that Jeffy pulled down his zipper and then urinated. He did not urinate while pulling down the zipper.
    Last edited by Al Ku; March 2nd, 2012 at 07:00 AM.

  10. #160
    Quote Originally Posted by dooku View Post
    However, movements at the wrist can not be properly described without including movements in the distal radioulnar joint in which the rotary actions of supination and pronation occur and this joint is therefore normally regarded as part of the wrist. [14]

    14. ^ Kingston 2000, pp 126-127


    * Kingston, Bernard (2000). Understanding joints: a practical guide to their structure and function. Nelson Thornes. ISBN 0748753990. http://books.google.com/books?id=6DH97qvthj4C.
    Golfdad: I understand this to mean that the "wrist" cannot be separated from the distal parts of the radioulnar joint. So this contradicts your claim that:
    Quote Originally Posted by golfdad View Post
    In either case, while the wrist flexion occurs, there is zero degree of elbow input or interference. Wrist joint is dynamic, doing flexion while the elbow joint is static, staying put in whatever position it is in.
    PS: I'm not trying to contradict you, just trying to get to the true facts.

  11. #161
    Quote Originally Posted by jaja View Post
    Golfdad: I understand this to mean that the "wrist" cannot be separated from the distal parts of the radioulnar joint. So this contradicts your claim that:

    PS: I'm not trying to contradict you, just trying to get to the true facts.
    I have no problem accepting that you are indeed trying to contradict me with a line taken out of a book that you have not read. And this is the beauty of internet,,,be all one wants to be. Just make a statement regardless of its validity and make others prove that one is wrong.

    The water you have ingested in the past week hopefully has passed some standard and contaminants are kept to a minimum that is scientifically possible and acceptable.

    So do you label water with lead 1 part per billion unclean and therefore unfit for drinking since it is not 100% H2O? If you do, there is really no other sources of H2O for you on this planet. If you don't, then you can probably relate that it is generally acceptable that pure wrist flexion is independent of elbow range of motion. In fact, Bernard Kingston's book title has the operative word in it,,,,"practical".

  12. #162
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    Quote Originally Posted by TeeAce View Post
    Footwedge, that's not possible unless you have your shaft and fingers parallel. In every other case PF will rotate the shaft and that's pure and simple geometry. There is no "how you do PF, there is just one way to do it in neutral position

    For example in those Jeffys PF videos, he doesn't make PF but also pronation and that way those two moves cancel each others.
    If there was any pronation, which I don't think there was, it was not nearly enough to "cancel out" the amount of counter-clockwise rotation you claim occurs with PF alone.


    Jeff

  13. #163
    TeeAce Guest
    Quote Originally Posted by Jeff Martin View Post
    If there was any pronation, which I don't think there was, it was not nearly enough to "cancel out" the amount of counter-clockwise rotation you claim occurs with PF alone.


    Jeff
    Maybe so and I watched your video again. There is one move where you go from full DF to PF and that rotates the face closed just like I've been saying. On other moves you get from DF to neutral and move your hand also other way (RD and slight pronation) and it gets the shaft to different position.

  14. #164
    birlyshirly Guest
    Quote Originally Posted by Jeff Martin View Post
    Odd question. The point of the demonstration is to show that PFing the left wrist does not, as Tapio claims, automatically create counter-clockwise forearm rotation (what everyone but Tapio calls supination). Anyhow, if I my forearm did respond to PFing by rotating clockwise (what everyone but Tapio calls pronation), I guess that would just prove Tapio doubly wrong!

    Here's the video.



    At this point I think you ought to get your own video camera (I've been just using my iPhone for these) and post your own demonstrations if you think I've done something wrong. As you will recall, our rule reads in part:

    And that includes criticisms of analyses that others have posted: if you think someone has done an analysis incorrectly, show us how to do it right! We don't need a peanut gallery here. With V1 software only costing $40, YouTube overwhelmed with great swing videos, and free photo hosting on Photobucket and other hosting sites, there are no excuses! Put up or shut up!



    Another odd question. Anyway, I don't think so; my arms are wandering a bit because they aren't braced. Again, check the video and, if you think I've done something wrong, show us how to do it right.


    Jeff
    Jeff - sorry if I've not been clear. The point I'm driving at is really what went back and forth between Teeace and Footwedge earlier in the thread as to what "pure palmar flexion" looks like. I agree with you that PF doesn't automatically or inevitably lead to either pronation or supination.

    I hope that we both understand each other OK. So what do you think caused the shaft to lay down in your video?

    I may have misunderstood footw, but I thought he saw that move as pure pf. But, by reference to your video, I think there's more going on than pure p.f., as evidenced by the closure of the gap between your hands and the cabinet.

    There's no video I can post to make this any clearer than what I've just written. No biggie, I hope.

  15. #165
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    Quote Originally Posted by TeeAce View Post
    Maybe so and I watched your video again. There is one move where you go from full DF to PF and that rotates the face closed just like I've been saying. On other moves you get from DF to neutral and move your hand also other way (RD and slight pronation) and it gets the shaft to different position.

    Here's the deal.

    When the club is "on-plane" and the wrists are in radial deviation (cocked), left forearm supination will steepen the shaft and put it above the plane unless some other compensation is made. Palmar flexion of the lead wrist (bowing) and dorsiflexion of the trail wrist (cupping or bending) is what good golfers do to keep the club on plane while supinating the lead forearm in the downswing. We can see Hogan doing that below:


    Name:  Screen Shot 2012-03-02 at 12.17.43 PM.png
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    We can also see you doing it in this video: your wrists are in RD; the lead forearm supinates (closing the face) and at the same time the lead wrist PFs and the trail wrist DFs. As a consequence, the shaft stays on-plane and you have successfully closed the clubface while keeping the shaft on plane, just like Hogan.





    You don't deny that the clubface closes and the forearm rotates, but you say the observed forearm rotation is not supination. However you have not cited any authority or publication that confirms this interpretation. From all the evidence, you have simply created your own definition. That's called "making things up", not evidence. Rotation of the forearm away from the body is unambiguously defined as supination, not PF.

    You have disagreed with this argument before but have provided no evidence beyond your opinion. You need to provide something beyond your personal views at this point.


    Jeff

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