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Post by dubiousgolfer on Mar 25, 2022 8:02:58 GMT -5
Hi S
Dr Kwon never said relax the wrists but to 'use' them which I assume will mean active torque.
DG
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Post by dubiousgolfer on Mar 25, 2022 9:14:14 GMT -5
Here is a reply to a comment made by someone on the you-tube video.
"Dr. Kwon, thank you so much for this lesson with Ben! When you say use the wrists more does this mean to relax them more or to actively make some motion?"
Reply
"In this case, more active wrist action. He tends to rotate the body during the FT quite a bit and active wrist action will slow it down."
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Post by syllogist on Mar 26, 2022 5:20:13 GMT -5
Hi DG,
Thanks for showing Dr. Kwon's reply regarding the use of the wrists and forward body rotation. In that case, I would not rely on Dr. Kwon's swing theories.
S
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Post by dubiousgolfer on Mar 26, 2022 10:14:13 GMT -5
Hi DG, Thanks for showing Dr. Kwon's reply regarding the use of the wrists and forward body rotation. In that case, I would not rely on Dr. Kwon's swing theories. S I am asking more questions about the physics viability of his instruction and if I hear back , will post an update. For example, here is an extract from Dave Tutelman's website in his article "Ben Hogan, Lee Comeaux, and the Right Hand Hit" and note that I have bolded/underlined a section below: www.tutelman.com/golf/swing/handhit.php"Bent forward - By the same reasoning, a forward shaft bend shows a negative, or retarding, wrist torque. Again, the force applied by the shaft is in the direction to straighten the shaft. The force applied to the clubhead by a forward-bending shaft is slowing the release of the clubhead." My QuestionIf a golfer was able to time and use active wrist torque in the late downswing (say after club horizontal) , wouldn't he be reducing the net 'negative' torque that his hands would be applying to the grip? Although the clubs angular velocity could be too large for the uncocking wrists to keep up , there is nothing to stop the golfer from trying to reduce that negative torque and therefore counter the slowing of the clubheads release caused by forward shaft bend. Or would this have a negligible affect on the release of the clubhead? DG
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Post by imperfectgolfer on Mar 26, 2022 10:14:36 GMT -5
I agree with DG that Kwon stated that one should use an active wrist motion, which he called "snapping the wrists" and he also claimed that it would slow down the rotary motion of the torso. Both claims make no sense to me. What does Kwon mean when he states that a golfer should actively snap the wrists to induce the release of PA#2? In his "forces/torques that are applied to the club handle" explanations he never discussed the application of an active wrist torque and he stated that the club releases when the trail hand's positive torque decreases starting between P5 => P5.5 while the MoF produced by the lead hand simultaneously starts to increase. Here is Kwon's graph. There is no evidence of an active wrist snapping maneuver in those graphs. Also, how could an active wrist snapping maneuver cause the torso's rotation to slow down? I am really surprised to see Kwon talk in such a non-scientific manner. Jeff.
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Post by dubiousgolfer on Mar 26, 2022 19:01:39 GMT -5
Dave Tutelman has responded to my emails regarding whether active wrist torque will slow the body rotation:
"You are right about the equal and opposite torque, and also about the large MOI. But the body MOI about the spine as an axis isn't orders of magnitude larger than the MOI of the club held at the handle. Even if it were 10 times as large (one order of magnitude), getting a 10% help with controlling body rotation may well be worth it.
So I just did a Q&D (that's engineer-speak for "quick and dirty") calculation of the MOI of an adult human torso. It appears to be less than 3 times that of a golf club torqued at the handle. That is not nearly a big a difference as either of us guessed.
Hope this answers your concern."
So it seems that if these equal and opposite torques do work their way from the wrist to the body , it is a possibility that body rotation can be impacted. I am still not wholly convinced whether it will slow body rotation or actually accelerate it. But if Ben Crane is using active wrist torque , it will need to be perfectly timed so that it doesn't hurt his clubhead speed and considering he is a 'PGA-Tour Pro' , maybe he has that capability.
DT has reiterated what he's written on his website but added a few more comments:
"My article on the right-hand hit deals with this extensively. My simulations showed that you not only have to be able to apply the torque, the timing has to be exquisite. And even so, there is not much clubhead speed to be gained unless you can apply a lot of exquisitely timed torque. Plausible amounts of torque will do almost nothing to help, and if introduced too early (say, 110msec before impact instead of 70msec) will actually hurt. Moreover, a little torque to "help" might not help as much you would have gotten from actually applying retarding torque to hold the lag"
My question: "If a golfer was able to time and use active wrist torque in the late downswing (say after club horizontal) , wouldn't he be reducing the net 'negative' torque that his hands would be applying to the grip? Although the clubs angular velocity could be too large for the uncocking wrists to keep up , there is nothing to stop the golfer from trying to reduce that negative torque and therefore counter the slowing of the clubheads release caused by forward shaft bend. Or would this have a negligible affect on the release of the clubhead?"
DT's reply: "Worse than negligible effect; in practice, it is usually harmful. If your wrists can't actually exceed the angular velocity of the club by enough to apply positive couple (and I don't know of anybody who can do that), then merely the effort of trying may be causing you to "strangle" the club and impose more negative torque than simply using a light grip and allowing the wrists to hinge."
DT says 'may be causing you to strangle the club' but I don't know of any research that can provide evidence of his opinion although it could be feasible. But it does seem that active plausible wrist torque , even if impeccably timed, will not cause any significant increase in clubhead speed.
DG
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Post by dubiousgolfer on Mar 27, 2022 5:55:31 GMT -5
Dr Sasho MacKenzie also agrees with Dr Kwon that active wrist torque will slow down body rotation. I have emailed Dr Mackenzie the following asking whether I have made an error in my thinking regarding equal and opposite reaction torques.
I'm assuming I have made an error because all these equal and opposite reaction torques about joints can be very confusing.
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1. An anti-clockwise torque applied by my left wrist from radial to ulnar deviation. 2. There will be an equal and opposite clockwise reaction torque on my left forearm (applied just above the wrist joint) 3. There will be an equal and opposite anti-clockwise reaction torque on my left humerus (applied just above my elbow joint) 5. There will be an equal and opposite clockwise reaction torque on my shoulder girdle (applied just above the shoulder joint) 6. There will be an equal and opposite anti-clockwise reaction torque on my ribcage (I don't know whether these torques act around the clavicle and the connecting AC and SC joints). 7. I am assuming that there is no joint between 'ribcage/spine/pelvis' other than the range of rotational motion offered by the facet joints in the different regions of the spine. Therefore 'ribcage/spine/pelvis' will turn anti-clockwise (ie. increase in body rotational speed in anti-clockwise direction not a decrease).
Have I made an error in my logic somewhere?
Now it gets complicated because I know the ribcage and spine are almost rigidly connected but can any regions of the spine be assumed to be a joint? If not and it is rigid , the 'ribcage/spine (especially lumbar section) /pelvis' will all end up rotating anti-clockwise. I can imagine if a person has got a very flexible spine maybe there will be an extra 'joint' (maybe in the thoracic region) and the pelvis will end up rotating clockwise a slight amount until the facet joints in the spine prevent any further range of motion.
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DG
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Post by syllogist on Mar 27, 2022 7:26:20 GMT -5
Hi DG,
I just read the answer you provided by DT. I can't see where DT directly answered your question about whether muscularly generated wrist release slows the body. Also, I re-watched the Kwon video at the point where Kwon talked about "using the wrists" to slow the body to avoid loss of balance. It's confusing considering that Ben asked directly if Kwon meant relaxation of the wrists and Kwon did not answer in the negative but then went on to describe "snapping" of the wrists and using them more. I could not tell if using them more meant to let them release passively or actively.
In any event, the "let it go" comment appeared to me to be more than just a concern about loss of balance, and that loss of balance was an indication of insufficient of mistimed wrist release. If one wanted to slow torso rotation just prior to the onset of release, it would appear to be far more reasonable to cease applying rotational effort to the torso for that purpose, and, in such case, the "let it go" would happen on its own.
S
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Post by dubiousgolfer on Mar 27, 2022 9:21:54 GMT -5
Hi S
You are correct that DT didn't actually confirm whether he thought the body slowed down or not but rather opined that wrist torque would have a significant effect on body rotation.
Could Ben Crane's balance issues be due to the fact that he wasn't (or is unable) to apply adequate left leg grf forces to counter the dynamic weight of the club?
DG
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Post by imperfectgolfer on Mar 27, 2022 9:32:52 GMT -5
DG, You wrote-: " So it seems that if these equal and opposite torques do work their way from the wrist to the body, it is a possibility that body rotation can be impacted." How did you come to this conclusion based on DT's vague reply invoking MOIs? Consider this swing video of the one-armed golfer - Logan Aldridge - who drives the ball >300 yards using a lead arm swinging technique. His club releases between P5.5 => impact. How can that PA#2 release phenomenon slow down torso rotation during his late downswing time period - considering the anatomical structure/functioning of the lead shoulder joint? How on earth can you imagine that the lead arm can apply a force through the lead shoulder socket to slow down the rotation of the upper torso? I personally cannot imagine how it could be biomechanicaly possible - despite your vague physics-based conjecturing about equal and opposite reactive torques. Even if there is a reactive torque operating at the level of the lead shoulder joint secondary to an active lead wrist uncocking action, how could that reactive torque slow down rotation of the upper torso considering the ball-and-socket anatomical structure of the lead shoulder joint? I would like to see you ask both Kwon and Sasho how it is physically possible for an active release of PA#2 (by using lead forearm muscles) to slow down the rotation of the upper torso torso between P5.5 => P7 and they need to provide a detailed explanation. I think that the torso (pelvis and upper torso) slows down in the later downswing to enable the club release phenomenon to be coordinated with the rotation of the body so that one can have the correct body/lead arm/club alignments at impact. One can reasonably argue that the targetward motion of the lead arm will slow down during a PA#2 release phenomenon due to the increased MOI of the lead arm/clubshaft unit, but I do not believe that it is physically possible for any reactive torque to cross the lead shoulder joint in order to slow down rotation of the torso. Jeff.
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Post by imperfectgolfer on Mar 27, 2022 12:50:06 GMT -5
I decided to watch this entire Kwon video. There are many issues where I disagree with Kwon. At the 5:15 minute time point, Kwon states that Ben Crane wrongly lowers his body at the start of the downswing in a manner demonstrated by Kwon at the 5:38 minute time point. Kwon states that any lowering of the body must happen during the re-centering phase where the upper torso is leftwards-tilted and Kwon states that it must be due to increased flexion of the lead knee. Kwon does not seem to like the "Sam Snead sit-down" move where the pelvis lowers due to increased hip joint flexion happening bilaterally and where both knee joints have increased flexion as seen in these capture images of Jamie Sadlowski.
Image 1 shows JS at address with his pelvis centered between his feet.
Image 2 shows JS at P4 and his pelvis is still centered although he has a rightwards-tilted upper torso/spine.
Image 3 shows JS performing the "Sam Snead sit-down" move, which involves increased hip joint flexion that causes the head to drop. Note that there is no re-centering move happening because his pelvis is already centered, and note that he has no reverse pivoting motion of his upper torso.
I think that the "Sam Snead sit-down" move is a very desirable swing action and I cannot understand why Kwon objects to that particular golf swing action.
At the 6:52 minute time point of his video, Kwon states that the main goal in the downswing is to "push down into the ground with the left foot and move the left side up".
I disagree with Kwon. I think that pushing down into the ground with the lead foot in order to elevate the lead side of the body happens secondarily/subsequently after P5, and that between P4 => P5 a golfer should be performing a hip-squaring action using the trail-sided lateral pelvic rotator muscles. I think that the lowering of the trail side of the pelvis that happens during a "Sam Snead sit-down" move helps to stabilise the trail leg/foot so that the trail sided lateral pelvic rotator muscles can efficiently rotate the pelvis counterclockwise away from the stabilised trail leg/foot.
Jeff.
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Post by dubiousgolfer on Mar 27, 2022 15:04:49 GMT -5
Dr Mann You said "How did you come to this conclusion based on DT's vague reply invoking MOIs?"I said "it is a possibility that body rotation can be impacted" because I haven't seen the proof yet. Personally , I have my doubts but I'm not 100% certain. Note I am doubtful about active wrist torque releasing PA#2 not an MOF induced release because they are not using the same mechanisms. You said: "His club releases between P5.5 => impact. How can that PA#2 release phenomenon slow down torso rotation during his late downswing time period - considering the anatomical structure/functioning of the lead shoulder joint? How on earth can you imagine that the lead arm can apply a force through the lead shoulder socket to slow down the rotation of the upper torso?
I personally cannot imagine how it could be biomechanicaly possible - despite your vague physics-based conjecturing about equal and opposite reactive torques."Because of Newtons 3rd Law. When you twist something it is also twisting back on you. When you push something it is also pushing back on you. I've mentioned an experiment before where you sit on a swivel chair with your feet off the ground and adduct your left arm horizontally across your chest . Now abduct the left arm away counterclockwise from your chest and observe that your chest and lower body will move together clockwise immediately. When you suddenly stop your left arm abducting , an equal and opposite torque will move your chest anti-clockwise for a split second before it also stops. Here is Chris Como demonstrating the physics (Newtons 3rd Law) by jumping off a diving board while swinging and demonstrating that his chest and lower body have experienced an equal and opposite torque. In this particular example I think he has contracted his oblique abdominals which will pull his ribcage and pelvis in opposite rotational directions. DG PS. Here is Dr Kwon's website for Joint Kinetics but its all really maths/physics and doesn't contain any detailed explanation of how 'muscles/tendons/ligaments/joints' create those equal and opposite forces/torques . I suspect it is even more complicated than the advanced mathematics he is using for his inverse dynamics analysis. www.kwon3d.com/theory/jntkin.htmlHere is the video by Dr Veronica Foster that offers an example explanation of how equal and opposite torques act across the joint (which will be the common axis of rotation). She talks about them and gives an easy example from 11:41 onwards.
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Post by imperfectgolfer on Mar 27, 2022 19:08:09 GMT -5
Dr Mann You said "How did you come to this conclusion based on DT's vague reply invoking MOIs?"I said "it is a possibility that body rotation can be impacted" because I haven't seen the proof yet. Personally , I have my doubts but I'm not 100% certain. Note I am doubtful about active wrist torque releasing PA#2 not an MOF induced release because they are not using the same mechanisms. You said: "His club releases between P5.5 => impact. How can that PA#2 release phenomenon slow down torso rotation during his late downswing time period - considering the anatomical structure/functioning of the lead shoulder joint? How on earth can you imagine that the lead arm can apply a force through the lead shoulder socket to slow down the rotation of the upper torso?
I personally cannot imagine how it could be biomechanicaly possible - despite your vague physics-based conjecturing about equal and opposite reactive torques."Because of Newtons 3rd Law. When you twist something it is also twisting back on you. When you push something it is also pushing back on you. I've mentioned an experiment before where you sit on a swivel chair with your feet off the ground and adduct your left arm horizontally across your chest . Now abduct the left arm away counterclockwise from your chest and observe that your chest and lower body will move together clockwise immediately. When you suddenly stop your left arm abducting , an equal and opposite torque will move your chest anti-clockwise for a split second before it also stops. Here is Chris Como demonstrating the physics (Newtons 3rd Law) by jumping off a diving board while swinging and demonstrating that his chest and lower body have experienced an equal and opposite torque. DG PS. Here is Dr Kwon's website for Joint Kinetics but its all really maths/physics and doesn't contain any detailed explanation of how 'muscles/tendons/ligaments/joints' create those equal and opposite forces/torques . I suspect it is even more complicated than the advanced mathematics he is using for his inverse dynamics analysis. www.kwon3d.com/theory/jntkin.htmlHere is the video by Dr Veronica Foster that offers an example explanation of how equal and opposite torques act across the joint (which will be the common axis of rotation). She talks about them and gives an easy example from 11:41 onwards. I can understand Newton's 3rd law from a physics perspective, but I cannot understand how it applies to an active lead wrist uncocking action that is happening between P5.5 => P7. If one adds a small muscular torque to the lead wrist uncocking action to make it more "active" then that force is acting roughly parallel to the swingplane in a downwards-and-forwards direction. If there is reactive torque in the opposite direction, then that torque must be going up the lead forearm and then the lead arm towards the lead shoulder socket area. If that reactive torque is large enough to reach the lead shoulder joint area, then what happens to that reactive torque at the level of the lead shoulder socket joint? Maybe it causes the lead arm to be moved in the direction of more adduction (less abduction) or maybe it causes the glenoid fossa area of the scapula to rotate backwards away from the target. However, why should it cause the upper torso's rotation to slow down when you consider the small magnitude of that "active" wrist uncocking torque? Here is Sasho's computer modelling graphs based on inverse dynamics. Note the small magnitude of the lead wrist uncocking torque and its short duration of action. Note that the torque causing a counterclockwise rotation of the torso is much larger in magnitude and that it is increasing in magnitude during the time period when the lead wrist uncocking torque is being applied and it continues to increase in magnitude all the way to impact.
Jeff.
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Post by dubiousgolfer on Mar 27, 2022 20:14:17 GMT -5
Dr Mann
I am also doubtful that an active wrist torque can have any significant effect on the torso rotation. Anyhow, even if a golfer experiences this retarding torso torque I imagine it would be dwarfed by the golfer using other contractions (ie. his abdominal obliques) or larger grfs via his feet to prevent his body pivot from stalling prematurely. Dr Kwon's instruction may cause other problems for Ben Crane if he cannot time his active wrist torque in some impeccable way.
I'm still waiting to see any evidence of shot accuracy using Dr Kwon's methods although he claims less shot dispersion.
DG
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Post by imperfectgolfer on Mar 28, 2022 15:01:30 GMT -5
Here is another controversial Kwon opinion expressed in his Ben Crane video that I consider to be irrational. Watch the video from the 29:00 - 31:50 minute time points. Kwon wants Ben to shift his pelvis more assertively away from the target as he start his backswing action, and he believes that it will allow Ben to therefore have more pelvic shift targetwards when he performs his re-centering move. First of all, Ben is not really following Kwon's advice - as seen in the following capture images from the 29:17 minute time point of the video.
Image 1 is at P3.5. Note that the outer border of his trail pelvis is still within the inner boundary of his trail foot.
Image 2 is at P4 where he has already performed the re-centering move. Note that he is actually squaring his pelvis during his re-centering move and he looks like he is performing the "Sam Snead sit-down" move (which Kwon does not recommend).
Note that there is very little pelvic shift happening during his re-centering move because he did not really shift his pelvis away from the target very much during his backswing action. What he was really doing was holding the flex in his trail knee and driving his trail hip joint into internal rotation during his backswing action.
Here are comparative capture images captured at the 24:19 minute time point of the video - captured before Kwon gave him advice to more assertively shift his pelvis away from the target at the start of his backswing.
Note that there is no difference in pelvic shift away from the target by P3.5 (image 1) and note there is the same amount of pelvic shift targetwards during his re-centering move (image 2) where he manifests the same "Sam Snead sit-down" move and the same degree of hip-squaring action during his re-centering move.
Although it is perfectly permissible to use a rightwards-loading pelvic motional pattern during the backswing action, there is no reason to believe that it is better than a centralised-loading pelvic motional pattern or a leftwards-loading pelvic motional pattern.
Jamie Sadlowski uses a centralised pelvic loading motional pattern.
Arnold Palmer used a leftwards-loading pelvic motional pattern.
Jeff.
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