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Post by imperfectgolfer on Jan 30, 2024 22:14:15 GMT -5
Dr Mann Yes, in my example images above the clubface will rotate in space but the clubface won't rotate about the club path arc, so there isn't any "about the shaft torque" or twist of the handle. The only examples I can think of where a twist in space of the handle can happen while in radial deviation (of about 90 degrees) is in the images below. The top image is where the lead arm becomes more vertical, while the other is the obvious flexion of the wrist. One can see for the top image that the white dot has rotated in space which will change the orientation of the clubface if intact LFFW/GFLW. Are we discussing the same issue or have I misinterpreted your previous post? DG PS. On reflection , I have corrected a sentence in a previous post as per below: "Only when the wrist has uncocked and the angle between the lead arm and shaft greater than 90 degrees can the M_Arm graph be used to assess the torque being applied 'about the shaft' (see green arrow in image further below)." You wrote-: " Yes, in my example images above the clubface will rotate in space but the clubface won't rotate about the club path arc, so there isn't any "about the shaft torque" or twist of the handle." I think that your demonstration/argument is irrelevant because if you maintain a 90 degree angle and do not release the club then it is impossible for there to even be a clubhead path arc. The "real life" reality is that Sergio is releasing the club between P5.5 => P6.5 and the clubface is closing more relative to the clubhead path during that time period. If the clubface is closing more relative to the clubhead path, then the phenomenon of handle twisting exists. It is debatable as to what biomechanical action is causing that handle twisting phenomenon. I think that it is primarily due to lead forearm supination that is concurrently happening when the lead hand moves along the hand arc path from its position at P5.5 to its position at P6.5. If you have a different explanation, please present that explanation for further discussion.
Jeff.
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Post by dubiousgolfer on Jan 30, 2024 23:08:38 GMT -5
When I look at this slow motion video of SG his left wrist looks extended at 2:12 and then anatomically flat at 2:19 (P6) , while also supinating his left forearm. I think the bowing of his left wrist while it's in significant radial deviation closes the clubface relative to club path. DG
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Post by imperfectgolfer on Jan 31, 2024 0:40:38 GMT -5
When I look at this slow motion video of SG his left wrist looks extended at 2:12 and then anatomically flat at 2:19 (P6) , while also supinating his left forearm. I think the bowing of his left wrist while it's in significant radial deviation closes the clubface relative to club path. DG I totally disagree. The amount of bowing is very small and there is no reverse motorcycle move happening which would cause the clubface to be closed relative to the watchface area of the lead lower forearm. Look again at these capture images. Look at the large amount of lead supination happening between P5.5 => P6.5 and note that the clubface-closing rate (relative to the clubhead path) is happening continuously in direct proportion to the amount of lead forearm supination happening per unit time. Note that the clubface remains straight-line-aligned with his lead lower forearm's radial bone at all times between P5.5 => P6.5 because it is rotating counterclockwise in direct proportion to the rate of lead forearm supination. Jeff.
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Post by dubiousgolfer on Jan 31, 2024 8:46:16 GMT -5
How about this as a another factor to closing the clubface relative to club path from P5.5-P6? Here is another video of SG where I have frame images below from P5.5-P6 . Note that his right elbow is nearly touching his right lower torso above his hip and he is lowering his forearm from a horizontal position to more vertical. See what happens to the white dot in the images further below when he does that type of movement while his right forearm is supinated. It rotates a significant amount and will therefore close the clubface relative to clubhead path. DG
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Post by imperfectgolfer on Jan 31, 2024 10:12:52 GMT -5
How about this as a another factor to closing the clubface relative to club path from P5.5-P6? Here is another video of SG where I have frame images below from P5.5-P6 . Note that his right elbow is nearly touching his right lower torso above his hip and he is lowering his forearm from a horizontal position to more vertical. See what happens to the white dot in the images further below when he does that type of movement while his right forearm is supinated. It rotates a significant amount and will therefore close the clubface relative to clubhead path. DG I cannot understand your white dot images and I have no idea what they represent. I also cannot understand why the trail forearm becoming more vertically aligned should have any clubface-closing effect considering the fact that the trail forearm is becoming more supinated between P5 => P6. I think that getting his trail forearm to become more vertical has an "anti-tumble" influence and it prevents any clubshaft steepening from happening when Sergio starts his lead forearm supination phenomenon early. Early lead forearm supination is also often associated with lead wrist palmar flexion that angles the clubshaft more underplane, which is an "anti-tumble" phenomenon.
However, I can clearly see that the lead palm is very horizontal at P5 and near-vertical at P6 and that a lot of lead forearm supination is required to produce that change. Why do you have a problem accepting the "idea" that lead forearm supination has a clubface-closing effect via the mechanism of a handle-twisting phenomenon - as shown by Phil Cheetham in his PhD paper's graphs below? Jeff.
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Post by dubiousgolfer on Jan 31, 2024 11:36:58 GMT -5
Dr Mann
I have no problem believing that lead forearm supination closes the clubface, but only when the angle between shaft lead arm is greater than 90 degrees.
Further, I have no issue with Phil Cheethams graph which basically shows about 14 degrees of supination between 'Release' and the purple arrow. If one worked out the degrees of supination between green arrow and purple arrow , I'd imagine it would be about 6-7 degrees.
The white dots show that the club has twisted in 3D space which will also change the face angle (if one visualises what will also happen to the clubface).
DG
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Post by imperfectgolfer on Jan 31, 2024 11:52:13 GMT -5
Dr Mann I have no problem believing that lead forearm supination closes the clubface, but only when the angle between shaft lead arm is greater than 90 degrees. Further, I have no issue with Phil Cheethams graph which basically shows about 14 degrees of supination between 'Release' and the purple arrow. If one worked out the degrees of supination between green arrow and purple arrow , I'd imagine it would be about 6-7 degrees. The white dots show that the club has twisted in 3D space which will also change the face angle (if one visualises what will also happen to the clubface). DG You wrote-: " I have no problem believing that lead forearm supination closes the clubface, but only when the angle between shaft lead arm is greater than 90 degrees." Here are your posted images.
Do you have a problem perceiving that lead forearm supination is causally responsible for closing the clubface relative to the clubhead path between image 2 and image 4 via the phenomenon of "early lead forearm supination combined with lead wrist palmar flexion"?
Jeff.
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Post by dubiousgolfer on Jan 31, 2024 12:34:23 GMT -5
Dr Mann
I'm fine with 'early lead forearm supination with lead wrist palmar flexion' because that combination keeps the shaft on plane.
DG
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Post by imperfectgolfer on Jan 31, 2024 12:45:32 GMT -5
Dr Mann I'm fine with 'early lead forearm supination with lead wrist palmar flexion' because that combination keeps the shaft on plane. DG You did not answer my question. My question is whether you believe that SG's "early lead forearm supination and lead wrist palmar flexion" action (which keeps the clubshaft on-plane) is causally responsible for the clubface-closing relative to the clubhead path phenomenon seen between image 2 and image 4? Jeff.
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Post by dubiousgolfer on Jan 31, 2024 19:00:03 GMT -5
Dr Mann I'm fine with 'early lead forearm supination with lead wrist palmar flexion' because that combination keeps the shaft on plane. DG You did not answer my question. My question is whether you believe that SG's "early lead forearm supination and lead wrist palmar flexion" action (which keeps the clubshaft on-plane) is causally responsible for the clubface-closing relative to the clubhead path phenomenon seen between image 2 and image 4? Jeff. Yes, I think it's a high possibility without any other evidence to prove otherwise. DG
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Post by imperfectgolfer on Feb 10, 2024 11:03:50 GMT -5
In a previous post on January 28th I posted the following (shortened) post-: "I n my last post, I quoted Terry Rowles as stating that weak trail hand grip strength players are producing their "about-the-shaft" clubface-closing action earlier and with greater magnitude and I could not understand how that is possible. Terry also stated to me in an email communication that Sasho MacKenzie had performed a small research study that proved that weak trail hand grip strength players produced more "about the shaft" torque than strong trail hand grip strength players.
I then decided to analyse Sasho's research study.
Here is a link to my analysis - perfectgolfswingreview.net/SashoTrailHandGripStudy.html
I addressed my analysis towards Terry and I asked many questions that I would like to see Terry Rowles (and/or Sasho MacKenzie and Phil Cheetham) answer." I never received a reply from Terry, but I did receive a reply from Sasho MacKenzie, who stated that he did not read my piece but he would be willing to answer a succinct question. So, I posed the following succinct question to Sasho-: "In your research study you showed that the pro golfers who used a weak trail hand grip produced a larger "about-the-shaft" torque which peaked after P6.5 and just before impact - what possible biomechanical action can the trail arm/forearm/wrist be executing that will cause the "about-the-shaft" torque to peak so late in the downswing and just before impact?" This is how Sasho answered the question - he stated that the torque required to produce an "about-the shaft" handle twisting phenomenon is not large and that it is only 1Nm in magnitude. He then stated that the torque could be applied by an unspecified "little passive soft tissue interaction in the hands". His reply blew my mind!!! I think that the idea that a pro golfer can produce the necessary "about-the-shaft" handle twisting phenomenon with minimal torque that only involves an unspecified soft tissue interaction between the trail hand and the club handle is ridiculously unscientific. I am flabbergasted by the stupidity of Sasho's reply.
Here is Sasho's own graph showing the timing/magnitude of lead forearm supinatory torque that he thinks is needed to rotate the clubshaft about its longitudinal axis in his forward dynamics model so that the clubface can become square to the clubhead path by impact. Note that the lead forearm supination torque starts between P5 and P5.5 and its torque peak value reaches ~20Nm before dropping off by ~P6.5. At that time, Sasho obviously believed that the lead arm/forearm/hand were causally responsible for the "about-the-shaft" handle twisting phenomenon routinely seen in all pro golfers.
Now, Sasho is claiming that the same "about-the-shaft" handle twisting phenomenon that is frequently seen in all pro golfers can be performed by the trail arm/forearm/wrist/hand entity using only 1NM of torque that is only applied after P6.5 via some unspecified "little passive soft tissue interaction" between the trail hand and the club handle - even though the "handle twisting phenomenon" is seen well before P6.5 in many pro golfers ( eg. Sergio Garcia's handle twisting phenomenon mainly happens between P5.5 => P6.5 - see this January 30th 10:03am post at newtongolfinstitute.proboards.com/thread/1061/sportsbox-video-face-openers-closers?page=2&scrollTo=13668 to read my analysis of SG's "handle twisting phenomenon"). Phew!!! My respect for Sasho's knowledge regarding golf swing biomechanics had taken a huge blow! Jeff.
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Post by dubiousgolfer on Feb 10, 2024 17:32:45 GMT -5
Dr Mann Is this bar chart produced by SMK the torque applied about shaft by both hands, where the trail hand was weak and strong? The difference in torque is very small approx 18 Ncm = 0.18 Nm To get an idea of how small that feels like, this is what I read on a physics forum what 1 Nm feels like: Stretch your arm out to the side as far and straight as possible, and have someone place an apple in your outstretched hand. Most apples are in the region of 100 grams, and most arms are in the region of a meter long from shoulder to fingertip. The increase you'll feel from the apple won't be exactly 1Nm, but you'll get an idea of the magnitude." Now imagine placing 4/5ths of that apple on your hand and feel the difference, which would be about 0.20 Nm. SMK is being statistically correct that there is a significant difference in the about shaft torque, but the actual difference is like blowing air from ones mouth on a wrench to help undo a nut. I doubt it can be proven that the trail hand was responsible for that tiny difference of 0.18 Nm. DG
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Post by imperfectgolfer on Feb 10, 2024 19:25:23 GMT -5
Dr Mann Is this bar chart produced by SMK the torque applied about shaft by both hands, where the trail hand was weak and strong? The difference in torque is very small approx 18 Ncm = 0.18 Nm To get an idea of how small that feels like, this is what I read on a physics forum what 1 Nm feels like: Stretch your arm out to the side as far and straight as possible, and have someone place an apple in your outstretched hand. Most apples are in the region of 100 grams, and most arms are in the region of a meter long from shoulder to fingertip. The increase you'll feel from the apple won't be exactly 1Nm, but you'll get an idea of the magnitude." Now imagine placing 4/5ths of that apple on your hand and feel the difference, which would be about 0.20 Nm. SMK is being statistically correct that there is a significant difference in the about shaft torque, but the actual difference is like blowing air from ones mouth on a wrench to help undo a nut. I doubt it can be proven that the trail hand was responsible for that tiny difference of 0.18 Nm. DG DG,
Interesting comment. I increasingly suspect that when Sasho did his inverse dynamic calculations that he assumed that the lead arm was not involved in the "about-the-shaft" handle twisting phenomenon, and he assumed that the trail hand could apply a very small amount of torque very late in the downswing after P6.5 to square the clubhead relative to the clubhead path. I can imagine that his calculations could possibly apply to a trail arm-only golf swing action. However, I cannot understand how he can make those calculations if the handle-twisting phenomenon is casually due to a pivot-induced lead arm swinging action, where the most likely cause of the "about-the-shaft" handle twisting phenomenon is a lead forearm supinatory motion - especially in Sergio Garcia's driver golf swing action where most of the "about-the-shaft" handle twisting phenomenon that squares the clubface relative to the clubhead path happens between P5.5 => P6.5. By P6.5, his clubface is nearly square to his clubhead path and very little additional "about-the-shaft" torque (= blowing air from one's mouth) will need to be applied after P6.5. Jeff.
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