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Post by tomdavis76 on Dec 26, 2013 16:27:35 GMT -5
Here we have Aiko Leong, Kel's student, who has a weak grip and shuts the face early in the downswing through supintion and palmar flexion. Does she remind you of anybody?
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Post by tomdavis76 on Dec 26, 2013 16:39:07 GMT -5
Aiko also has less clubface rotation than Hogan: Shut the face, fight the hook.
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Post by imperfectgolfer on Dec 26, 2013 18:56:46 GMT -5
Jeffy,
You wrote-: "How is any of that relevant to the simple fact of geometry, which is all three players need similar amounts of clubface rotation from there to impact? It doesn't matter how they got there or the clubface's relationship to the left forearm.".
I think that we probably measure degrees of clubface rotation differently. I measure it relative to the clubhead arc. Gainey has a very strong left hand grip and his clubface is actually square to his CH arc at P6, and therefore he doesn't have to rotate his left forearm/arm or clubface at all between P6 and P7, while Hogan and Furyk have to do rotate their left forearm/FLW and clubface counterclockwise by similar amounts. because they don't use a strong left hand grip.
You also wrote-: "Mickelson's clubface must rotate at least 30 degrees more than Hogan's and Furyk's." So what? PM's lead forearm/FLeadW may be less rotated towards square by P6 and he may have to rotate a small amount more between P6 and P7 to get the back of his lead forearm/FLeadW square to the target by impact. However, what's the significance of that fact?
You also wrote-: "Who said the clubface had to be "abnormally closed"? It is 30 degrees more closed than Mickelson's and equally closed relative to me:"
This is a new admission by you to say that your clubface and Hogan's clubface are equally closed. KM (and you) previously argued that Hogan's clubface was more closed than your clubface at P6.
You also wrote-: "Here we have Aiko Leong, Kel's student, who has a weak grip and shuts the face early in the downswing through supintion and palmar flexion. Does she remind you of anybody?"
I have previously demonstrated (by comparing AL to GW) that her greater degree of clubface closure is due to twistaway and not due to a combined "early left forearm supination + left wrist palmar flexion" phenomenon. Her clubface is more closed to the CH arc at P6 (and also more closed relative to the back of her left forearm) than your clubface (which you said is equally closed as Hogan's), so she doesn't remind me of either you or Hogan. By the way, she still rotates the back of her left forearm/FLW the same amount between P6 and P7 (compared to a golfer with a weak grip) even though she uses a twistaway phenomenon, because the clubface-closing effect of twistaway automatically disappears between P6 and P7. Jeff.
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Post by tomdavis76 on Dec 26, 2013 23:14:35 GMT -5
Jeffy, You wrote-: " How is any of that relevant to the simple fact of geometry, which is all three players need similar amounts of clubface rotation from there to impact? It doesn't matter how they got there or the clubface's relationship to the left forearm.". I think that we probably measure degrees of clubface rotation differently. I measure it relative to the clubhead arc. Gainey has a very strong left hand grip and his clubface is actually square to his CH arc at P6, and therefore he doesn't have to rotate his left forearm/arm or clubface at all between P6 and P7, while Hogan and Furyk have to do rotate their left forearm/FLW and clubface counterclockwise by similar amounts. because they don't use a strong left hand grip.Try again. They are all within a few degrees of each other relative to the arc. I don't think 35 degrees is a "small amount more" when Hogan only has to rotate 10 degrees. Phil's 45 degrees of rotation is 4.5 times Hogan's. Do you think that may introduce a "timing element"? Apparently it does, since Phil is one of the worst drivers on tour. You must be kidding. "Equally closed relative to me" means Hogan's clubface is closed relative to mine in an amount equal to how much it is closed relative to Phil's clubface. Nonsense, that's just more of your word games. "Twistaway" is just another name for the combination of PF and supination. More absurdity. Hogan's and Aiko's clubfaces are at identical angles relative to the arc. That's a ridiculous claim and is easily dispelled by PFing and supinating early in the downswing. Without "fight the hook" offsets, the ball will go left.
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Post by imperfectgolfer on Dec 27, 2013 11:43:42 GMT -5
Jeffy wrote-: " Here we have Aiko Leong, Kel's student, who has a weak grip and shuts the face early in the downswing through supination and palmar flexion". He also wrote-: "T wistaway" is just another name for the combination of PF and supination." It is so easy to to demonstrate the idiocy of Jeffy's claims. He has stated that event A (early left forearm supination +PF) causes event B (clubface closure). However, that causal relationship is only possible (according to David Hume the philospher who developed the rules of causality) if the two events are time-contiguous events and if event A precedes event B with 100% consistency. That causal link could not possibly be true if event B preceded event A. The reality is that AL closes her clubface in her backswing and it is an incontestable fact that she already has a closed clubface at P4. Image 1 shows AL with a closed clubface (relative to the CH arc and also relative to the back of her left forearm/hand) at P4. If you compare image 2 to images 4&5, you can clearly see that the degree of clubface closure doesn't change and it is the same at P5.5/P6 that it was at P4. In other words, AL's clubface is already closed at P5.2 (image 3) - before the phenomenon of "early left forearm supination + PF) begins. That proves that Jeffy's causal association claim is false! What is causing AL's clubface to be closed at P4? If anybody has a better explanation than twistaway (which is not the same thing as "early left forearm supination + PF" as Jeffy irrationally claims) then I would like to read that explanation. Jeffy also posted this comparative photo of Hogan and PM. Jeffy wrote-: " I don't think 35 degrees is a "small amount more" when Hogan only has to rotate 100 degrees". He thinks that he is measuring the degrees of rotation of the clubface between P6 and P7 by drawing those lines. That's crazy! Consider this diagram. The back line is the ground. The red dot is the golf ball. The grey line is a clubface that is vertical at P6 (when the golfer's clubshaft is parallel to the ball-target line and parallel to the ground). Note that if the clubface is on the TSP that it measures 15 degrees differently - even though both golfers have the back of their left FLW parallel to the ball-target line, and even though both golfers will have to rotate their FLW by the same amount to get their clubface square to the target at impact (presuming that they both adopt a weak/neutral left hand grip and that all other impact biomechanical alignment parameters are the same for the two golfers). I also think that it is irrational to draw straight lines like that and think that it is reflective of the change in clubface rotation relative to the CH arc that is going to happen between P6 and P7. Jeffy also posted this image of Gainey and Hogan. Note that Gainey has the same 100-101 degrees measurement as Hogan. However, that measurement has nothing to do with how much the clubshaft is going to be rotating around its longitudinal axis between P6 and P7. Hogan's clubshaft has to rotate about its longitudinal axis ( = gamma rotation) between P6 and P7 because he uses a weak left hand grip, and he therefore has to use a PA#3 release action to square the clubface by impact - as demonstrated in the following diagram. Note how the clubface (black line) rotates counterclockwise as it travels along the CH arc (red arrowed arc) and that phenomenon is biomechanically due to a PA#3 release action (mainly a left forearm supination phenomenon that rotates the left forearm/FLW counterclockwise) between P6 and P7. However, Gainey uses a very strong left hand grip (like Sadlowski). That means that there is no rotation of the clubface relative to the CH arc happening between P6 and P7 - as demonstrated in the following diagram. Jeffy is mixing-up two very different issues - i) a change in clubface angulation relative to the ground due to the fact that the clubshaft's motion in 3-D space is angular, and changes in Gainey's clubface angulation between P6 and P7 will directly reflect the degree of change in clubshaft angulation between P6 and P7, even though there is zero gamma rotation (rotation of the clubshaft about its longitudinal axis) between P6 and P7 and ii) a change in clubface rotation relative to the CH arc between P6 and P7.
Addendum added later: I also stated the following with respect to AL-: " By the way, she still rotates the back of her left forearm/FLW the same amount between P6 and P7 (compared to a golfer with a weak grip) even though she uses a twistaway phenomenon, because the clubface-closing effect of twistaway automatically disappears between P6 and P7." Jeffy responded as follows-: " That's a ridiculous claim and is easily dispelled by PFing and supinating early in the downswing. Without "fight the hook" offsets, the ball will go left.If Jeffy were correct, then the back of her FLW cannot face the target at impact following the release of PA#3 (which has to happen biomechanically in any golfer who uses a weak left hand grip) because that would mean that her clubface would be facing left-of-the-target. However, here is the "real life" reality of AL's swing. Note that the i) back of her left forearm ii) back of her flat left hand and ii) clubface all face the target at impact and that the clubface is not closed relative to the back of her left forearm at impact or the back of her left forearm/left hand at P7.3 (image 2). So, what happened to the clubface-closing phenomenon that AL manifested at P6 where the clubface was closed relative to both the back of her left forearm and back of her left hand? Jeff.
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Post by imperfectgolfer on Dec 27, 2013 13:11:01 GMT -5
To those forum members and guests who don't think that Aiko Leong is using a twistaway maneuver in her backswing action, consider the following video and capture images. Here are capture images of her backswing action Image 1 is at the start of her takeaway when the clubhead is about 6 inches back from the ball. Note that her clubface is square to the CH arc and not closed relative to the back of her left forearm. Image 2 is in the later takeaway. Note that her clubface appears slightly closed relative to the CH arc and note that her fingers look like they have "turned under" as prescribed by Joe Dante for his twistaway takeaway action. Image 3 is at P2.5 and you can clearly see that her clubface is closed relative to the CH arc and also relative to the back of her left forearm. Image 4 shows her at P4 - note that the clubface is closed to her CH arc and also closed to the back of her left forearm (and back of her left hand which is now straight-line aligned with the back of her left forearm because she now has an AFLW). To make the degree of clubface closure more obvious - here is a comparison between Henrik Stenson (who also uses a neutral left hand grip but who doesn't use a twistaway maneuver) and Aiko Leong at comparable P positions. If you don't believe that AL's clubface is closed due to a twistaway maneuver, then what do you think is causing her clubface to be that closed at P4? Jeff.
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Post by tomdavis76 on Dec 27, 2013 17:57:53 GMT -5
To those forum members and guests who don't think that Aiko Leong is using a twistaway maneuver in her backswing action, consider the following video and capture images. Here are capture images of her backswing action Image 1 is at the start of her takeaway when the clubhead is about 6 inches back from the ball. Note that her clubface is square to the CH arc and not closed relative to the back of her left forearm. Image 2 is in the later takeaway. Note that her clubface appears slightly closed relative to the CH arc and note that her fingers look like they have "turned under" as prescribed by Joe Dante for his twistaway takeaway action. Image 3 is at P2.5 and you can clearly see that her clubface is closed relative to the CH arc and also relative to the back of her left forearm. Image 4 shows her at P4 - note that the clubface is closed to her CH arc and also closed to the back of her left forearm (and back of her left hand which is now straight-line aligned with the back of her left forearm because she now has an AFLW). To make the degree of clubface closure more obvious - here is a comparison between Henrik Stenson (who also uses a neutral left hand grip but who doesn't use a twistaway maneuver) and Aiko Leong at comparable P positions. If you don't believe that AL's clubface is closed due to a twistaway maneuver, then what do you think is causing her clubface to be that closed at P4?Jeff. Take a closer look at Aiko's address position: left shoulder in ER, left forearm pronated and clubface square. So, at address, the clubface is already "closed" relative to the left forearm. In the takeaway, the clubface stays square to the arc and "closed" to the left forearm, as it was at address. A bit past P2 Aiko's left wrist is still extended, as it was at address. In contrast, there is a lot of flexion in the left wrist at P6. Since "twistaway" is simply a combination of supination and palmar flexion, "twistaway" is missing at this point in the backswing. The clubface at this point hasn't closed at all, it just hasn't opened very much from address. By P3, Aiko's left and right humeris have rotated clockwise (left shoulder IR and right shoulder ER), which opens the clubface. There is still some left wrist extension. No sign of a "twistaway" yet. After P4, in transition, the left and right humeris have rotated even more clockwise, "laying the club off", with the shaft pointing well to the left of the target. Aiko has by this time begun left wrist palmar flexion, which makes the clubface face more towards the sky. Many will call this action "shutting" or "closing", but it is really just delofting.
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Post by tomdavis76 on Dec 27, 2013 18:54:34 GMT -5
Jeffy wrote-: " Here we have Aiko Leong, Kel's student, who has a weak grip and shuts the face early in the downswing through supination and palmar flexion". He also wrote-: "T wistaway" is just another name for the combination of PF and supination." It is so easy to to demonstrate the idiocy of Jeffy's claims. He has stated that event A (early left forearm supination +PF) causes event B (clubface closure). However, that causal relationship is only possible (according to David Hume the philospher who developed the rules of causality) if the two events are time-contiguous events and if event A precedes event B with 100% consistency. That causal link could not possibly be true if event B preceded event A. The reality is that AL closes her clubface in her backswing and it is an incontestable fact that she already has a closed clubface at P4. Image 1 shows AL with a closed clubface (relative to the CH arc and also relative to the back of her left forearm/hand) at P4. If you compare image 2 to images 4&5, you can clearly see that the degree of clubface closure doesn't change and it is the same at P5.5/P6 that it was at P4. In other words, AL's clubface is already closed at P5.2 (image 3) - before the phenomenon of "early left forearm supination + PF) begins. That proves that Jeffy's causal association claim is false!It doesn't matter when the PF begins or the supination begins: the two together create what is called a "twistaway". Aiko begins to PF towards the end of her backswing and increases it in transition. You think that PF closes the clubface, but it doesn't: it delofts the clubface and shifts the clubhead onto a flatter plane. During the late backswing and transition, right shoulder ER and left shoulder IR rotate the left and right humeris clockwise, opens the clubface, and flattens the shaft plane. If right shoulder ER and left shoulder IR are maintained or increased in the downswing, as Aiko does, the only way to get the clubface closed and the shaft steepened is through left forearm supination. Without steepening the shaft in the downswing through left forearm supination, the clubhead will pass over the ball. You can see how much "early supination" takes place below. So, there you have it: early supination and PF, or "twistaway".
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Post by tomdavis76 on Dec 27, 2013 19:57:54 GMT -5
Jeffy also posted this comparative photo of Hogan and PM. Jeffy wrote-: " I don't think 35 degrees is a "small amount more" when Hogan only has to rotate 100 degrees". He thinks that he is measuring the degrees of rotation of the clubface between P6 and P7 by drawing those lines. That's crazy! Consider this diagram. The back line is the ground. The red dot is the golf ball. The grey line is a clubface that is vertical at P6 (when the golfer's clubshaft is parallel to the ball-target line and parallel to the ground). Note that if the clubface is on the TSP that it measures 15 degrees differently - even though both golfers have the back of their left FLW parallel to the ball-target line, and even though both golfers will have to rotate their FLW by the same amount to get their clubface square to the target at impact (presuming that they both adopt a weak/neutral left hand grip and that all other impact biomechanical alignment parameters are the same for the two golfers). You don't understand simple geometry. If Hogan's clubface is ten degrees open to the arc, he needs to rotate it ten degrees to get it square. Makes no difference what his grip is. And if Phil's is 35 degrees open, he needs to rotate it shut 35 degrees. Assume the clubshaft is flat on the ground at P6 and the clubface is vertical. How much rotation around the shaft will be required to have the face square at P7? Zero. The type of grip is irrelevant.
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Post by tomdavis76 on Dec 27, 2013 20:21:28 GMT -5
I also stated the following with respect to AL-: " By the way, she still rotates the back of her left forearm/FLW the same amount between P6 and P7 (compared to a golfer with a weak grip) even though she uses a twistaway phenomenon, because the clubface-closing effect of twistaway automatically disappears between P6 and P7." Jeffy responded as follows-: " That's a ridiculous claim and is easily dispelled by PFing and supinating early in the downswing. Without "fight the hook" offsets, the ball will go left.If Jeffy were correct, then the back of her FLW cannot face the target at impact following the release of PA#3 (which has to happen biomechanically in any golfer who uses a weak left hand grip) because that would mean that her clubface would be facing left-of-the-target.However, here is the "real life" reality of AL's swing. Obviously, Aiko has used many "fight the hook" elements to keep the clubface from closing to the path in spite of early supination. The clubface is still ten degrees open to the arc a bit past P6, just like Hogan. The degree of clubface closure relative to the back of the left hand and forearm is irrelevant. They both need ten degrees of rotation arond the shaft to get to square.
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Post by tomdavis76 on Dec 27, 2013 20:27:04 GMT -5
Jeffy also posted this image of Gainey and Hogan. Note that Gainey has the same 100-101 degrees measurement as Hogan. However, that measurement has nothing to do with how much the clubshaft is going to be rotating around its longitudinal axis between P6 and P7. Hogan's clubshaft has to rotate about its longitudinal axis ( = gamma rotation) between P6 and P7 because he uses a weak left hand grip, and he therefore has to use a PA#3 release action to square the clubface by impact - as demonstrated in the following diagram. Note how the clubface (black line) rotates counterclockwise as it travels along the CH arc (red arrowed arc) and that phenomenon is biomechanically due to a PA#3 release action (mainly a left forearm supination phenomenon that rotates the left forearm/FLW counterclockwise) between P6 and P7. However, Gainey uses a very strong left hand grip (like Sadlowski). That means that there is no rotation of the clubface relative to the CH arc happening between P6 and P7 - as demonstrated in the following diagram. Jeffy is mixing-up two very different issues - i) a change in clubface angulation relative to the ground due to the fact that the clubshaft's motion in 3-D space is angular, and changes in Gainey's clubface angulation between P6 and P7 will directly reflect the degree of change in clubshaft angulation between P6 and P7, even though there is zero gamma rotation (rotation of the clubshaft about its longitudinal axis) between P6 and P7 and ii) a change in clubface rotation relative to the CH arc between P6 and P7.That is all complete rubbish. I am simply looking at the clubface angle relative to the arc. If both are ten degrees open to the arc, both require ten degrees of closing. Grip doesn't matter.
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Post by imperfectgolfer on Dec 27, 2013 21:57:38 GMT -5
I hope that guests and forum members are getting an education by noting how differently Jeffy and I perceive reality and how differently we interpret a golfer's biomechanical actions. I find it fascinating! Let's continue. Jeffy posted an image of AL at address and he stated-: " Take a closer look at Aiko's address position: left shoulder in ER, left forearm pronated and clubface square. So, at address, the clubface is already "closed" relative to the left forearm." Of course the clubface is closed relative to the left forearm at address but it has nothing to do with those mentioned biomechanical features. It is simply due to the fact that she bends her left wrist so that she can have her clubshaft perpendicular to the ball-target line at address. I have drawn a red line along the length of her left forearm and a blue line along the length of her clubshaft to show that they are not in a straight line relationship due to the fact that she has bent her left wrist. When she starts the backswing, she increasingly bends her right wrist back and flattens her left wrist thereby eliminating the left wrist bend so that the clubface becomes parallel (neutral) relative to the back of her left forearm 6" after the start of the takeaway - see image 1 below. Note that the clubshaft and her left arm are now in a straight line relationship and AL no longer has a bent left wrist that causes the clubshaft to be angled targetwards relative to her left arm (as it was at address). Jeffy then posted this comparative image of AL at P2+ and P6. Jeffy then stated-: " A bit past P2 Aiko's left wrist is still extended, as it was at address. In contrast, there is a lot of flexion in the left wrist at P6. Since "twistaway" is simply a combination of supination and palmar flexion, "twistaway" is missing at this point in the backswing. The clubface at this point hasn't closed at all, it just hasn't opened very much from address.". He claims that the clubface has not closed, and that twistaway is not present in her P2+ image. I believe that he is wrong! First of all, Jeffy defines twistaway as being due to "left forearm supination + PF" which obviously doesn't happen in the takeaway. However, that is not how Joe Dante described the twistaway action in the early 1960s. Here is a link to Joe Dante's description. www.golf-swing-magic.com/golf-backswing3.htmlJoe Dante describes the action as a "turning of the left hand under" in such a way that the the fingers will torque the grip thereby closing the clubface relative to the back of the left forearm. One can clearly see that the clubface is closed relative to the back of the left forearm during a twistaway maneuver in one of his diagrammatic images and it has nothing to with the combination of "left forearm supination + PF". Note that the clubface is closed relative to the back of his left hand. That is due to the finger curling action. It is not causally due to PF because in the absence of twistaway, a "pure" PF motion would only angle the clubface backwards and it would still be parallel to the back of the left hand. Jeffy also states that AL's clubface is not closed at P2+. I think that he is wrong! Here is a comparison between Henrik Stenson's and Aiko Leong's takeaway action. I have drawn a red line parallel to their clubface. One can clearly see that HS's clubface is neutral relative to the back of his left arm while AL's clubface is closed relative to the back of her left arm at P2 (image 1). Note that they both have an intact LAFW at this time point (clubshaft is straight-line-aligned with the left arm), but HS has a GFLW while AL's left wrist is more flattened due to her twistaway maneuver (ala Joe Dante). AL's left wrist is not as palmar flexed as that left wrist in Joe Dante's diagram because she is not contracting her flexor digitorum profundus muscles as much. Left wrist palmar flexion only happens if one continues to activate the flexor digitorum profundus muscles even more than the amount needed to curl the fingers into the palm, and that is not happening in ALs backswing action. I have also included comparative images at P2.5 (image 2) to demonstrate how much more AL's clubface is closed (relative to her left forearm ) compared to HS. One can also see enough of AL's left finger knuckles to see that they are curled under in a way that is not seen in Hs's left hand. Jeffy then wrote-: " By P3, Aiko's left and right humeris have rotated clockwise (left shoulder IR and right shoulder ER), which opens the clubface. There is still some left wrist extension. No sign of a "twistaway" yet.That's crazy of Jeffy to claim that she is opening her clubface at P3. There is no image of her clubface at P3 in the swing video because it was out of the camera image's frame. The closest I could get to P3 was P2.5+ and one can clearly see that the clubface is still closed (relative to the left forearm) to the same degree as it was at P2 (see image 2 below). Jeffy then wrote-: " After P4, in transition, the left and right humerus have rotated even more clockwise, "laying the club off", with the shaft pointing well to the left of the target. Aiko has by this time begun left wrist palmar flexion, which makes the clubface face more towards the sky. Many will call this action "shutting" or "closing", but it is really just delofting." Jeffy wrongly claims that she only starts to PF her left wrist after starting the downswing transition and he calls the clubface delofted (rather than closed) even though it is closed relative to the back of her left forearm. Amazing!!! First of all, the "laid-off action" happens during the backswing between P3.5 and P4 and the clubface is as closed to the back of her left forearm at P4 as it was at P3.5. I have captured AL's end-backswing action in three sequential images. One can see how AL lays her clubshaft-off between image 2 and image 3 by continuing to rotate her left forearm clockwise and that causes the clubshaft to drop to a shallower (more horizontal) plane. However, note that it doesn't change the relationship of the clubface relative to the back of her left forearm - it is as closed in image 2 as it is in image 3. It is obvious to me (and hopefully to other forum members and guests) that AL uses a twistaway maneuver (ala Dante) that closes the clubface relative to the back of her left forearm during her backswing action. By contrast, this is what Jeffy believes-: " You think that PF closes the clubface, but it doesn't: it delofts the clubface and shifts the clubhead onto a flatter plane." That delofting phenomenon only describes the change in the relationship of the clubshaft/clubface to her left arm between P3.5 and P4 as the club droops off-plane below the plane of her left arm. It doesn't explain why the clubface was closed relative to the left forearm all the way between P2 and P4. Jeff.
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Post by imperfectgolfer on Dec 27, 2013 22:41:09 GMT -5
Jeffy posted this comparative image of Hogan and PM. He then wrote-: " You don't understand simple geometry. If Hogan's clubface is ten degrees open to the arc, he needs to rotate it ten degrees to get it square. Makes no difference what his grip is. And if Phil's is 35 degrees open, he needs to rotate it shut 35 degrees." I presume that he gets those 10 degree and 35 degrees values by subtracting 90 degrees from 100 degrees and 135 degrees. Amazingly, he thinks that those values represent reality! How can you use measurements performed on a 2-D image when the camera is not perfectly square to the clubhead arc at the point of measurement? I regard those measured angles as being meaningless, and they tell us nothing about how much Hogan and Mickelson have to rotate their left forearm, and therefore clubface, between P6 and P7 in order to square the clubface. It reminds me of Jeffy's similar silliness when he posted DTL images to show that a golfer's clubshaft was off-plane in the mid-downswing even though the clubshaft ws not parallel to the front of the front of the camera lens. I am therefore not surprised that Jeffy is still making the same fundamental mistake today - showing that he has still not learned that you cannot make precise measurements and draw meaningful lines if the clubshaft is angled relative to the front of a DTL camera lens. I also wrote the following with respect to Gainey-: " Jeffy is mixing-up two very different issues - i) a change in clubface angulation relative to the ground due to the fact that the clubshaft's motion in 3-D space is angular, and changes in Gainey's clubface angulation between P6 and P7 will directly reflect the degree of change in clubshaft angulation between P6 and P7, even though there is zero gamma rotation (rotation of the clubshaft about its longitudinal axis) between P6 and P7 and ii) a change in clubface rotation relative to the CH arc between P6 and P7." Jeffy responded as follows-: " That is all complete rubbish. I am simply looking at the clubface angle relative to the arc. If both are ten degrees open to the arc, both require ten degrees of closing.Jeffy even believes that Gaineys clubface is 10 degrees open to his clubhead arc even though golfers who use a very strong left hand grip keep the clubface square to the clubhead arc throughout the entire downswing. See this slide show of Domenic Mazza's backswing and downswing action - and note how the clubface is always square to the CH arc due to the fact that he uses a very strong left hand grip. www.golfdigest.com/golf-instruction/swing-sequences/2011-02/photos-domenic-mazza#slide=1Jeff.
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Post by tomdavis76 on Dec 27, 2013 23:05:59 GMT -5
I hope that guests and forum members are getting an education by noting how differently Jeffy and I perceive reality and how differently we interpret a golfer's biomechanical actions. I find it fascinating! Let's continue. Jeffy posted an image of AL at address and he stated-: " Take a closer look at Aiko's address position: left shoulder in ER, left forearm pronated and clubface square. So, at address, the clubface is already "closed" relative to the left forearm." Of course the clubface is closed relative to the left forearm at address but it has nothing to do with those mentioned biomechanical features. It is simply due to the fact that she bends her left wrist so that she can have her clubshaft perpendicular to the ball-target line at address. I have drawn a red line along the length of her left forearm and a blue line along the length of her clubshaft to show that they are not in a straight line relationship due to the fact that she has bent her left wrist. Yes, the bent left wrist at address is consistent with the pronated left forearm and externally rotated left shoulder. Her face is closed relative to her forearm at address. Your description is dead wrong: her left wrist doesn't flatten until late in the backswing, just before P4. And the clubface angle relative to her forearm doesn't change. Thanks for the link. Here are the critical illustrations: One can easily see that the "twistaway" involves palmar flexion of the left wrist and supination of the left forearm relative to the "non-twistaway". Torquing the fingers of the left hand can assist the PFing, but isn't really necessary. Obviously, Aiko's takeaway, or any part of her backswing, doesn't look anything like the illustration on the left below.
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Post by imperfectgolfer on Dec 27, 2013 23:43:55 GMT -5
It is fascinating to see how Jeffy thinks.
Jeffy wrote-: "Your description is dead wrong: her left wrist doesn't flatten until late in the backswing, just before P4. And the clubface angle relative to her forearm doesn't change."
I didn't mean that her left wrist flattens to an AFLW. I mean that the left wrist is slightly less bent. How else can the clubshaft become straight-line-aligned with the left arm 6" into the start of the takeaway action?
Jeffy also wrote regarding the Dante diagram-: "One can easily see that the "twistaway" involves palmar flexion of the left wrist and supination of the left forearm relative to the "non-twistaway". Torquing the fingers of the left hand can assist the PFing, but isn't really necessary.
I think that Jeffy obviously doesn't understand the biomechanics underlying a twistaway action. That Dante diagram showing marked left wrist PF only happens if the degree of twistaway (due to active muscular contraction of the flexor digitorum muscles to the left 3rd, 4th and 5th fingers) becomes so great in magnitude that it starts to PF the left wrist. If one starts activating the flexor digitorum muscles, the first biomechanical phenomenon will be i) increased finger flexion involving the finger DIP joints because the tendon inserts into the base of the distal pahalanx. Then ii) the PIP joint becomes increasingly flexed, iii) then the MP joint becomes increasingly flexed if the degree of muscular contraction intensifies further and and finally iv) the left wrist joint will become flexed if muscular contraction is maximized. AL only gets to the end of stage 3 between P2-P3.5 and she doesn't palmar flex her left wrist as seen in Dante's full twistaway action, which is so extreme in magnitude that it causes the left forearm to secondarily supinate.
Also, if Jeffy believes that twistaway is nothing more than PF + supination, and that there is no finger curling action secondary to active finger flexion then why does the clubface become closed relative to the back of the left hand in that Dante diagram?
How else can one explain why AL's clubface is closed to the back of her left forearm at P2, P2.5 and P3.5 in those images - compared to HS's similar P positions? What does Jeffy think is causing her clubface to be closed (relative to her left forearm) while HS's clubface is neutral relative to his left forearm? I look forward to reading his explanation.
Jeff.
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