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Post by dubiousgolfer on Apr 10, 2020 8:16:21 GMT -5
Dr Mann/UG Here are some kinematic graphs from Phil Cheethams website www.philcheetham.com/pelvis-and-thorax-transition-plus-spine-rotation/It doesn't show any pelvis/thorax sway but it does seem to show that the pelvis and thorax are rotating counter-clockwise (from a top view) before P4. DG PS. Wouldn't this 'X-Factor' stretch be increased by lateral movement to the target while the arms are finishing the backswing by P4 ? Therefore I would assume that any pelvic/thorax targetwards shift would start happening as the pelvis/thorax are rotating 'Counter-Clockwise' before reaching P4. I've not seen any evidence that this 'X-Factor' stretch can significantly increase clubhead speed but it might be a 'feel' trigger to help time the correct kinematic sequence.
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Post by imperfectgolfer on Apr 10, 2020 9:35:23 GMT -5
UG, You wrote-: " To me, this idea is about swing center manipulation to promote an ideal swinging action. From p1 to p3.9 the swing center moves slightly rightwards, as this loads the right hip for a better CW turn. From p3.9 to p4, the swing center moves slightly leftwards back the p1 position or a bit further left as some pros do (Rory), for a better subsequent CCW turn." What swing center are you writing about - lower or upper? I presume that you are talking about the lower swing center, which reflects pelvic motion. Here is Rory's 3D graph showing pelvic rotation. The dotted blue line represents the P4 position. Note that the nadir of his pelvic rotation graph happens well before P4 and that the clockwise rotation of the pelvis is slowing down just before P4, as he starts his "squat move". During his "squat move", which I believe starts just before P4, the graph shows that his pelvis is not continuing to significantly rotate in a clockwise direction. Here are capture images showing Rory's "squat move". Image 1 is at P1, image 2 is at P3.9, image 3 is at P4 and image 4 is at P4.05. I have drawn red lines alongside the outer border of his upper thighs at P1. Image 2 shows that Rory is using a rightwards loading pelvic motional pattern. Images 3 and 4 show Rory starting his "squat move" where the pelvis is not continuing to significantly rotate clockwise and where the pelvis is going to start rotating counterclockwise very soon after P4.05. Here is Jamie Sadlowski's 3D graph. Note that JS's pelvic rotation graph (red graph) reaches its nadir well before P4, and that his pelvis is actually rotating counterclockwise between P3.9 and P4. So, if you think that his lower swing center is moving targetwards between P3.9 and P4, then it must be happening during the early phase of his counterclockwise rotation of the pelvis.
I think that the major difference between Jamie and Rory is that they both have a "squat move", but Jamie's pelvis is already rotating counterclockwise while he is first starting to squat while Rory is starting to squat with virtually no pelvic rotary motion during the early phase (P3.9 => P4.05 phase) of his "squat move".
Jeff.
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Post by dubiousgolfer on Apr 10, 2020 10:39:49 GMT -5
Not sure whether this helps but here is another Phil Cheetham graph showing pelvic sway (not sure whether this a representative sample of PGA pro golfers) This one looks a bit different because it shows pelvis targetwards movement while 'pelvis angle' reaching its max fractionally before P4 (or at P4). Here is also JS's pelvis and thorax sway graphs DG PS. looks like there is pelvic/thorax sway targetwards while he is also rotating them CCW before P4 (see Dr Mann's previous JS graph).
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Post by utahgolfer on Apr 10, 2020 11:33:11 GMT -5
Holy moley, that boy has a body built to twist and a neuromuscular system to time it all up!
Jeff, it is fun to try to figure out reality. I can definitely see the squat move but I think this facilitates a bit more CW rotation of the pelvis at the same time. I don't see any CCW pelvic rotation at this point.
But, whatever is exactly happening, it appears clear that this move helps to adjust his swing center more to the left during transition. And, I assume Rory is adjusting his swing center left with his upper torso shoulder rotation, too.
I think it is remarkable that the swing center moves during the first part of the backswing, during the transition, during the downswing, and during the follow-through. The swing center doesn't move much, but its manipulation appears to be very important.
UG
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Post by dubiousgolfer on Apr 10, 2020 11:46:53 GMT -5
Hi UG There seems to be a few useful graph info on this jeffygolf forum jeffygolf.com/showthread.php?1114-OK-let-s-suppose-Mike-Finney-is-right-about-what-Dr-Kwon-s-analysis-will-showThe interesting graph about JS is that he doesn't seem to use much radial deviation in his wrist . Its seems to be a large decrease in 'left wrist ulnar deviation' combined with a large increase in cupping (both happening from address to P4) . Apparently , the combination of both provides the lag according to Jeff Martin. So JS doesn't seem to use an intact LAFW with all that left wrist extension happening (look at JS top graph shown below - not sure who Elite golfer is). DG
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Post by imperfectgolfer on Apr 10, 2020 12:12:08 GMT -5
Holy moley, that boy has a body built to twist and a neuromuscular system to time it all up! Jeff, it is fun to try to figure out reality. I can definitely see the squat move but I think this facilitates a bit more CW rotation of the pelvis at the same time. I don't see any CCW pelvic rotation at this point. But, whatever is exactly happening, it appears clear that this move helps to adjust his swing center more to the left during transition. And, I assume Rory is adjusting his swing center left with his upper torso shoulder rotation, too. I think it is remarkable that the swing center moves during the first part of the backswing, during the transition, during the downswing, and during the follow-through. The swing center doesn't move much, but its manipulation appears to be very important. UG I now agree that Rory does not have any CCW rotation of his pelvis during the first phase of his "squat move" between P3.9 - P4.05, while Jamie (and many other pro golfers) have much more CCW rotation happening as soon as they start to squat. I don't understand why any golfer would want to rotate the pelvis clockwise during their squat move, and I cannot understand how initiating a squat move will biomechanically facilitate a CW rotation. Rory's pelvis demonstrates very little change in its degree of rotation between P3.9 - P4.05 according to his 3-D graph and his capture images. Jeff.
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Post by imperfectgolfer on Apr 10, 2020 12:24:04 GMT -5
Hi UG There seems to be a few useful graph info on this jeffygolf forum jeffygolf.com/showthread.php?1114-OK-let-s-suppose-Mike-Finney-is-right-about-what-Dr-Kwon-s-analysis-will-showThe interesting graph about JS is that he doesn't seem to use much radial deviation in his wrist . Its seems to be a large decrease in 'left wrist ulnar deviation' combined with a large increase in cupping (both happening from address to P4) . Apparently , the combination of both provides the lag according to Jeff Martin. So JS doesn't seem to use an intact LAFW with all that left wrist extension happening (look at JS top graph shown below - not sure who Elite golfer is). DG It is very difficult for me to accept that Jamie does not have significant radial deviation of his left wrist at his P4 position. Look at this capture image. He obviously has an ulnar-deviated left wrist at address, and it certainly looks like he has significant radial deviation of his left wrist at P4 although not to the same degree compared to P1 (where it is deviated a lot in an ulnar direction). It could be that the large degree of left wrist extension at P4 allows him to angle the clubshaft back a lot with less radial deviation - because he uses a very strong left hand grip. You also wrote-: "So JS doesn't seem to use an intact LAFW with all that left wrist extension happening (look at JS top graph shown below - not sure who Elite golfer is).
A reminder - the intact LAFW concept does not apply to a golfer who uses a very strong left hand grip (and we discussed this issue in another thread). Jeff.
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Post by dubiousgolfer on Apr 10, 2020 18:09:29 GMT -5
Many thanks Dr Mann - yes thanks for reminding me.
DG
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Post by dubiousgolfer on Apr 11, 2020 7:54:43 GMT -5
DG, You quoted the SLAP book as follows-: " Helps to stretch the muscles and load the swing dynamically * Pressure shift from right to left foot (when the body moves forward towards target) provides a stable base for the unwinding of the upper body from P4. * Enables the golfer swing 'all-out' without risk of losing balance or wasting energy * Initial move forward with feet, legs and hips sets up a chain of movements in the upper body that allows the transport of the club forwards along the proper swing path. * Helps produce the proper 'fall of the club' where the clubhead actually moves away from the ball as it nears P4 to automatically move the clubhead on an inside path during the downswing. It says the 'fall of the club' is so important that , if done properly it single-handedly eliminates problems related to swing path. * Helps move the lower body out of the way of the upper body to allow the correct swing path to occur." Do you really find those vague statements helpful? Where is the "evidence" that weight-pressure is moving dramatically from the right foot to the left foot during the transition? What does it mean to state "without wasting energy"? How does the targetwards movement of the legs/pelvis at the transition cause the upper body to secondarily move in such a way that the club will move forward along the proper swing path? How does a movement of the lower body targetwards at the transition cause the proper "fall of the club"? How does a movement of the lower body targetwards at the transition cause the lower body to get out of the way of the upper body? Jeff. Absolutely in agreement. In fact there are quite a few books I have which are going to the local charity after this lockdown. DG
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Post by dubiousgolfer on Apr 11, 2020 9:41:44 GMT -5
Dr Mann Is some of your analysis for JS's swing (on your website) incorrect considering these graphs we are seeing above? You said on your website: I now personally think that is biomechanically advantageous to not allow the pelvis to sway rightwards in the early backswing, and I think that is biomechanically better to simply withdraw the right buttocks (pull the right buttocks back away from the ball-target line) while keeping the right knee slightly flexed throughout the backswing. Jamie Sadlowski adopts this practice and he doesn't allow his pelvis and right knee to sway rightwards (away from the target) during his backswing. Note that the outer border of his right pelvis is well within the inner border of his right foot at the end of his backswing (image 6).
Graph: Pelvis sways -1.3 inches away from target but re-centres by about P4 Thorax sways approx. -2 inches away from target by P4 , then sways targetwards to approx. +1.3 inches during the early-mid downswing , then sways away from target approx. -2.6 inches by impact. ADDENDUM: You said "Another characteristic feature of Jamie Sadlowski's downswing is the arching of his spine (away from the target) in the late downswing, and the fact that he maintains that marked degree of secondary axis tilt throughout the followthrough. His torso only becomes more erect during the mid-late finish phase of his swing. I presume that he adopts that marked degree of secondary axis tilt to ensure that he maintains his balance during his super-fast downswing pivot action (while his arms/clubshaft are catapulted at a super-fast speed in the direction of the target). "
This is covered by the blue graph line (top graph below): You said: Note that the clubface is still facing slightly towards the ball at the end-takeaway position (toe of the club is not pointing straight up towards the sky) - and that is due to the fact that he does not utilise any left forearm rotary/pronatory movement in his takeaway (as occurs in a standard left arm swinger's action). His left arm is already internally rotated at address, and he simply pulls his internally rotated left arm back away from the target during the takeaway.
Graph: Confirms your opinion above You said at P3: Note that his left wrist has upcocked to nearly a 90 degree angle and that phenomenon is causally related to the fact that he is allowing his right elbow to start bending much more during the mid-backswing. Also, note that his right wrist is bending backwards (dorsiflexing) without cocking upwards and that biomechanical phenomenon allows him to keep his clubshaft on-plane in his mid-backswing. Graph: It is a decrease in ulnar deviation and increased extension of his left wrist At around P 3.2 His right elbow has a roughly 90 degree bend and his right forearm flying wedge has a perfect relationship with respect to his left arm flying wedge. This position is a perfect end-backswing position for many professional golfers, and it would not necessarily be biomechanically advantageous to over-swing beyond this top-of-the-backswing endpoint, because the left arm/clubshaft can become "disconnected" from the torso during any arm over-swinging maneuver.Graph: As before there is no intact LAFW applicable in JS's swing. You said: However, Jamie Sadlowski continues to over-swing beyond this standard top-of-the-backswing endpoint by turning his shoulders another 20 degrees and by lifting his arms upwards so that his clubshaft moves above his neck and crosses the line. To get his clubshaft to cross the line (and move-off plane), he has to upcock his right wrist and that causes his left wrist to become more scooped/cupped by the end of his backswing.Graph: Confirms the above ,left wrist extension happening up to P4. You said: Jamie Sadlowski has ultra-flexible wrists - note how much his left wrist has cocked in a radial direction by the end of his backswing (image 6). That increased degree of left wrist upcocking allows him to increase his clubhead lag even more by the end of his backswing.
Graph: Suggests that the lag is caused by decrease in ulnar deviation and increased extension of left wrist You said: It is important to note that Jamie Sadlowski doesn't change the degree of internal rotation of his left arm during his left arm's backswing travel motion. From his address position (image 1) to his end-backswing position (image 6), his left arm has moved through an arc of rotation of about 165-180 degrees - without requiring any increased degree of left arm internal rotation within the left shoulder socket joint. This anatomical phenomenon is only possible because he has a marked degree of left scapular mobility and a very loose/pliant left shoulder joint.
Graph: There are no measurements of internal/external rotation of his left humerus in the shoulder socket But there is left forearm rotation graph: The left forearm seems to be in a pronated position at address approx. +70 degrees, his left forearm remains constant for 0.3 secs then seems to supinate to approx -10 degrees at P4 , then continue to supinate in the early downswing up to -31 degrees , then pronate all the way to impact +20 degrees You said : One can see that he first shifts-rotates his pelvis so that his pelvis becomes square to the ball-target line by the end of the early downswing. The left-lateral shift of the pelvis is not a pelvic slide motion - any visual impression of a left-lateral slide motion of the pelvis (as seen from a face-on view) is merely a visual impression that is due to the fact that he is re-weighting his left leg as the left buttocks is pulled back towards the tush line. That re-weighting action causes the left knee to move left-laterally, and this left knee movement gives him a characteristic "sit-down" look when the pelvis becomes square to the ball-target line. During this hip squaring action, which produces his "sit down" look, his pelvis is simply rotating without any left-lateral sliding (look at the left-most part of his white belt and note that it doesn't move more leftwards during the early downswing - although the left knee moves more leftwards).Graph: Correlates with the above -there is very little sway -virtually none - from P4-P7 You said: Note that the back of his left hand and dorsum (back) of his left forearm remain parallel to the ball-target throughout the entire late downswing, which means that his left hand is not rotating into impact. In other words, the absence of any left forearm supinatory rotational movement means that there is no hand roll-over action in his late downswing (no involvement of PA#3). Graph: Left forearm supinates to approx -10 degrees at P4 , then continue to supinate in the early downswing up to approx. -27 degrees , then pronate all the way to impact +20 degrees Is the above a correct comparison of your own analysis vs the graphs above? DG PS. Not sure whether I've interpreted the left forearm pronation/supination graph correctly (doesn't make sense to me). Almost seems as if JS is exerting some 'tumbling action' in the early downswing. In his P6 position, his shaft is above his TSP , maybe he steepened his early downswing and that cause this extra supination in the graph to -27 degrees.
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Post by imperfectgolfer on Apr 11, 2020 13:37:29 GMT -5
Dr Mann Is some of your analysis for JS's swing (on your website) incorrect considering these graphs we are seeing above? You said on your website: I now personally think that is biomechanically advantageous to not allow the pelvis to sway rightwards in the early backswing, and I think that is biomechanically better to simply withdraw the right buttocks (pull the right buttocks back away from the ball-target line) while keeping the right knee slightly flexed throughout the backswing. Jamie Sadlowski adopts this practice and he doesn't allow his pelvis and right knee to sway rightwards (away from the target) during his backswing. Note that the outer border of his right pelvis is well within the inner border of his right foot at the end of his backswing (image 6).
Graph: Pelvis sways -1.3 inches away from target but re-centres by about P4 Thorax sways approx. -2 inches away from target by P4 , then sways targetwards to approx. +1.3 inches during the early-mid downswing , then sways away from target approx. -2.6 inches by impact. ADDENDUM: You said "Another characteristic feature of Jamie Sadlowski's downswing is the arching of his spine (away from the target) in the late downswing, and the fact that he maintains that marked degree of secondary axis tilt throughout the followthrough. His torso only becomes more erect during the mid-late finish phase of his swing. I presume that he adopts that marked degree of secondary axis tilt to ensure that he maintains his balance during his super-fast downswing pivot action (while his arms/clubshaft are catapulted at a super-fast speed in the direction of the target). "
This is covered by the blue graph line (top graph below): You said: Note that the clubface is still facing slightly towards the ball at the end-takeaway position (toe of the club is not pointing straight up towards the sky) - and that is due to the fact that he does not utilise any left forearm rotary/pronatory movement in his takeaway (as occurs in a standard left arm swinger's action). His left arm is already internally rotated at address, and he simply pulls his internally rotated left arm back away from the target during the takeaway.
Graph: Confirms your opinion above You said at P3: Note that his left wrist has upcocked to nearly a 90 degree angle and that phenomenon is causally related to the fact that he is allowing his right elbow to start bending much more during the mid-backswing. Also, note that his right wrist is bending backwards (dorsiflexing) without cocking upwards and that biomechanical phenomenon allows him to keep his clubshaft on-plane in his mid-backswing. Graph: It is a decrease in ulnar deviation and increased extension of his left wrist At around P 3.2 His right elbow has a roughly 90 degree bend and his right forearm flying wedge has a perfect relationship with respect to his left arm flying wedge. This position is a perfect end-backswing position for many professional golfers, and it would not necessarily be biomechanically advantageous to over-swing beyond this top-of-the-backswing endpoint, because the left arm/clubshaft can become "disconnected" from the torso during any arm over-swinging maneuver.Graph: As before there is no intact LAFW applicable in JS's swing. You said: However, Jamie Sadlowski continues to over-swing beyond this standard top-of-the-backswing endpoint by turning his shoulders another 20 degrees and by lifting his arms upwards so that his clubshaft moves above his neck and crosses the line. To get his clubshaft to cross the line (and move-off plane), he has to upcock his right wrist and that causes his left wrist to become more scooped/cupped by the end of his backswing.Graph: Confirms the above ,left wrist extension happening up to P4. You said: Jamie Sadlowski has ultra-flexible wrists - note how much his left wrist has cocked in a radial direction by the end of his backswing (image 6). That increased degree of left wrist upcocking allows him to increase his clubhead lag even more by the end of his backswing.
Graph: Suggests that the lag is caused by decrease in ulnar deviation and increased extension of left wrist You said: It is important to note that Jamie Sadlowski doesn't change the degree of internal rotation of his left arm during his left arm's backswing travel motion. From his address position (image 1) to his end-backswing position (image 6), his left arm has moved through an arc of rotation of about 165-180 degrees - without requiring any increased degree of left arm internal rotation within the left shoulder socket joint. This anatomical phenomenon is only possible because he has a marked degree of left scapular mobility and a very loose/pliant left shoulder joint.
Graph: There are no measurements of internal/external rotation of his left humerus in the shoulder socket But there is left forearm rotation graph: The left forearm seems to be in a pronated position at address approx. +70 degrees, his left forearm remains constant for 0.3 secs then seems to supinate to approx -10 degrees at P4 , then continue to supinate in the early downswing up to -31 degrees , then pronate all the way to impact +20 degrees You said : One can see that he first shifts-rotates his pelvis so that his pelvis becomes square to the ball-target line by the end of the early downswing. The left-lateral shift of the pelvis is not a pelvic slide motion - any visual impression of a left-lateral slide motion of the pelvis (as seen from a face-on view) is merely a visual impression that is due to the fact that he is re-weighting his left leg as the left buttocks is pulled back towards the tush line. That re-weighting action causes the left knee to move left-laterally, and this left knee movement gives him a characteristic "sit-down" look when the pelvis becomes square to the ball-target line. During this hip squaring action, which produces his "sit down" look, his pelvis is simply rotating without any left-lateral sliding (look at the left-most part of his white belt and note that it doesn't move more leftwards during the early downswing - although the left knee moves more leftwards).Graph: Correlates with the above -there is very little sway -virtually none - from P4-P7 You said: Note that the back of his left hand and dorsum (back) of his left forearm remain parallel to the ball-target throughout the entire late downswing, which means that his left hand is not rotating into impact. In other words, the absence of any left forearm supinatory rotational movement means that there is no hand roll-over action in his late downswing (no involvement of PA#3). Graph: Left forearm supinates to approx -10 degrees at P4 , then continue to supinate in the early downswing up to approx. -27 degrees , then pronate all the way to impact +20 degrees Is the above a correct comparison of your own analysis vs the graphs above? DG PS. Not sure whether I've interpreted the left forearm pronation/supination graph correctly (doesn't make sense to me). Almost seems as if JS is exerting some 'tumbling action' in the early downswing. In his P6 position, his shaft is above his TSP , maybe he steepened his early downswing and that cause this extra supination in the graph to -27 degrees. DG, Many good questions. In the face of those 3D graphs, I am willing to modify some of my opinions, but I will remain resolutely obstinate (narrow-minded) regarding some of those 3D graphs when they seem to be incompatible with my subjective viewing of 2D-capture images. My many critics, who believe that 3D graphs are infallibly accurate, will detest my obstinacy and they will invariably reject my personal opinions based on my subjective viewing of 2D-capture images. Starting with your first comment regarding pelvic sway, I regard a 1" amount of sway as being so very small that I cannot accurately determine that small amount using capture images. I will therefore stick to my general opinion that there is a negligible amount of pelvic sway motion in JS's backswing pelvic motion - because a small pelvic sway amount of 1" is biomechanically insignificant. The next issue relates to the left wrist cocking phenomenon. According to the 3D graph, JS's left wrist is ~63 degrees ulnar deviated at address, and ~8 degrees ulnar deviated at P4. That represents a change in left wrist angle of ~55 degrees in the direction of radial deviation (which they define as being less ulnar deviated). I can accept the ~55 degree of change in left wrist angle in the plane of left wrist ulnar => radial deviation as probably being accurate, but I cannot accept the "fact" that the left wrist is not radially deviated at P4. Here are my capture images of JS's left wrist angles at P1, P4 and P7. I define a neutral left wrist as existing when the fingers of the extended left hand are straight-line-aligned with the left forearm. Seeing that I cannot see the fingers I will use the metacarpal bones as a surrogate marker. The base of the metacarpal bones are closer to together than the knuckle-end of the metacarpal bones so they cannot be perfectly straight-line-aligned with the left forearm, but the degree of error is small. I normally use the 2nd metacarpal bone as my reference point relative to the lower radial bone of the left forearm and I regard the left wrist as being neutral when they are straight-line-aligned. At P1 (image 1) the blue line (representing the 2nd metacarpal bone) is deviated in an ulnar direction relative to the left forearm's lower radial bone (red line) and the degree of ulnar deviation is slightly greater at P1 (image 1) than it is at P7 (image 3). However, the blue line looks radially deviated at P4 (image 2) and I simply cannot accept that it is still ulnar-deviated! If you look at the angular change in degrees between image 1 and image 2, it could be about 55 degrees so I am not disputing the amount of change in left wrist angle in the plane of ulnar-radial deviation. Moving on to changes in left forearm supination/pronation. The 3d graph implies that the left forearm is ~75 degrees supinated at P1 with little change during the early takeaway, but it claims that the left forearm is ~10 degrees pronated at P4. That represents a change of 85 degrees! I cannot understand how that is possible! Here are capture images at P1.5, P3 and P4. I use the left antecubital fossa as my reference point and I think that his left humerus is internally rotated to roughly the same degree at P1.5, P3 and P4. If the left humerus is actually more internally rotated at P4, then I would find it difficult to accept that the degree of change in the degree of left humeral IR is >30 degrees. I then compare the left lower radial bone (or the watchface area of the left lower forearm) relative to the left antecubital fossa to roughly assess any change in the degree of left forearm pronation - and the left forearm looks about 30 degrees more pronated at P4 compared to P1.5. However, I find it difficult to accept a change of 85 degrees! Now, let's consider the amount of left forearm supination that happens between P5.5 and P7. According to the 3D graph, the left forearm is ~25 degrees pronated at P5.5 and ~15 degrees supinated at impact. That amounts to a change of 40 degrees in the direction of left forearm supination. Here are capture images - image 1 is at P5.5 and image 2 is at impact. The left forearm definitely looks more pronated at P5.5 compared to impact, and the degree of change could be 40 degrees. What is very important is to compare it to the elite golfer's graph where the change in left forearm supinatory degrees between P5.5 and impact is ~72 degrees, which is ~32 degrees more than Jamie's and that would represent the release of PA#3 presuming, of course, that the elite golfer has a less strong left hand grip. What is very puzzling to me is that both graph's show a similar amount of left forearm supination of ~70-75 degrees at address. How is that possible - presuming that the elite golfer does not have an ultra-strong left hand grip like JS? How can the left forearm be ~70 degrees supinated at address in a golfer who adopts a very strong left hand grip and where the back of the left hand faces the ball-target line at address? Also, compare JS's left forearm at P7 compared to P1 - it does not look that there is a difference of ~60 degrees in the degree of left forearm supination when the back of the left hand (and watchface area of the left lower forearm) both face the ball-target line to roughly the same degree at P1 and P7!
Regarding the left wrist flexion-extension graphs, they seem to be credible. The 3D graph's left wrist is ~63 degrees extended at P4 and by a roughly similar amount (~ 50 degrees) at P5.5, but only 10 degrees extended at impact. Those figures seem to be compatible with the capture images above. Jeff.
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Post by dubiousgolfer on Apr 11, 2020 19:58:36 GMT -5
Many thanks Dr Mann
I think you are correct about the left wrist looking radially deviated at P4. I don't know how they calibrate the zero position for wrist deviation in TPI although we had the same issue with the zero point for flexion and extension.
I think the TPI graph for lead forearm rotation has +y axis = pronation , while -y axis = supination
Addendum 16th Sept 2023: I assumed the P in the top right hand corner of JS's lead wrist graphs meant pronation but that is wrong. The +y axis is supination while the -y axis is pronation. So my post is incorrect !
P1 ~ + 75 DEGREES PRONATED P4 ~ - 10 DEGREES SUPINATED P5.5 ~ -25 DEGREES SUPINATED P7 ~ + 10 DEGREES PRONATED
So is it feasible that JS is supinating his lead forearm as his backswing arm plane steepens to P4 then steepens a small amount during the downswing by P5.5 before pronating into P7?
If my assumption above is accurate then I find it a very strange biomechanical movement for a golfer to pronate into impact.
DG
PS. It could be that JS has to instinctively pronate slightly into impact to offset any excessive forward shaft bend that could be closing the clubface by P7.
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Post by imperfectgolfer on Apr 11, 2020 21:47:03 GMT -5
Many thanks Dr Mann I think you are correct about the left wrist looking radially deviated at P4. I don't know how they calibrate the zero position for wrist deviation in TPI although we had the same issue with the zero point for flexion and extension. I think the TPI graph for lead forearm rotation has +y axis = pronation , while -y axis = supination P1 ~ + 75 DEGREES PRONATED P4 ~ - 10 DEGREES SUPINATED P5.5 ~ -25 DEGREES SUPINATED P7 ~ + 10 DEGREES PRONATED So is it feasible that JS is supinating his lead forearm as his backswing arm plane steepens to P4 then steepens a small amount during the downswing by P5.5 before pronating into P7? If my assumption above is accurate then I find it a very strange biomechanical movement for a golfer to pronate into impact. DG PS. It could be that JS has to instinctively pronate slightly into impact to offset any excessive forward shaft bend that could be closing the clubface by P7. It would make no sense to me if the TPI graph for lead forearm rotation has +y axis = pronation , while -y axis = supination because that would mean that a golfer is pronating the left forearm in the late downswing into impact. How is that possible? All TGM swingers have to use a PA#3 release action (= left forearm supinatory motion) in the late downswing in order to square the clubface by impact with the amount being inversely proportional to left hand grip strength. Jeff.
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Post by dubiousgolfer on Apr 12, 2020 9:37:31 GMT -5
Dr Mann
Apologies, I think you are correct about the +y axis being supination after seeing this KM video below.
I also found another few frames in slow motion of JS and its clear from the 1st few seconds that his left wrist is supinating into impact (look at the brand emblem on his left glove).
What confused me is the fact that JS has a strong grip at address so I expected his forearm to show a more 'pronated' reading from P1. I cannot understand how a golfer with a very strong grip can have a supinated forearm at address (unless he has circumducted with left wrist extension combined with ulnar deviation)
DG
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Post by imperfectgolfer on Apr 12, 2020 10:08:46 GMT -5
DG, You wrote-: " What confused me is the fact that JS has a strong grip at address so I expected his forearm to show a more 'pronated' reading from P1. I cannot understand how a golfer with a very strong grip can have a supinated forearm at address (unless he has circumducted with left wrist extension combined with ulnar deviation)". I have no difficulty understanding how a pro golfer (who has a very strong left hand grip) can have a slightly supinated left forearm at address if his left humerus is very internally rotated at address. However, what I cannot understand is how JS can have 70 degrees of left forearm supination at address (when the golfer in the KM-video only has ~32 degrees of left forearm supination at address). That's another reason why I question the validity of those JS-3D graphs. Addendum added later: I have made new capture images of JS as seen from a DTL perspective. I have drawn a red line down the middle of his antecubital fossa and a blue line along his left lower radial bone, and that allows one to roughly assess the degree of supination/pronation that exists at P1.2 (image 1), P6 (image 2) and near impact (image 3). Note that his left humerus is internally rotated at P1.2 and that his left forearm is supinated, but the degree appears to be in the range of ~45 degrees.
Note that his left humerus is slightly less internally rotated at P6, and that his left forearm is slightly pronated. Note that his left forearm is slightly supinated at near-impact (image 3), but not as supinated as one would expect because he uses very little PA#3 release action and the back of his left hand is still facing the ball-target line, and not facing the target, at impact.
According to the JS-3D graphs that you posted, JS supposedly had 70 degrees of left forearm supination at P1.2 and 15 degrees at impact, and that amounts to a difference of ~60 degrees. However, if you compare image 1 to image 3, it does not appear that there is such a large 60 degrees of difference in the amount of left forearm supination between P1.2 and P7.
Jeff.
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