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Post by imperfectgolfer on Jul 31, 2021 20:53:18 GMT -5
Dr Mann One thing is confusing about those PGA pro kinematic graphs in the previous posts. If any of those golfers were DH'ers , the blue and brown graphs would be aligned on top of each other post impact (ie. the lead arm and club shaft would be moving at the same angular velocity from P7-P7.2). Could this be a data sampling frequency issue? See extract from your downswing chapter. Image 1 is at impact, image 2 is at P7.2 and image 3 is at P7.4. Image 4 is a composite image showing the targetwards motion of her left hand and clubshaft/clubhead between P7 and P7.4. The accompanying diagram depicts her left shoulder socket in black, her left arm in red and her clubshaft in green. The blue dot represents her left hand and the orange dot represents the clubhead. Note how Kelli Oride keeps the back of her left hand (GFLW) continuously facing the target between P7 and P7.4 and there is very little counterclockwise rotation of her left hand happening between P7 and P7.4. Also, note that her left hand (represented by the blue dot in the diagram) moves targetwards at an angular velocity that perfectly matches the angular velocity of the clubhead (orange dot) and that action allows Kelli Oride to keep her LFFW intact, and it thereby prevents the clubshaft from bypassing her left arm (from an angular rotational perspective) between P7 => P7.4. That phenomenon defines a DH-hand release action and it allows a golfer to more reliably keep the clubface square to the clubhead arc during that early followthrough time period. DG PS. Those kinematic graphs were taken by the same AMM system that takes only 240 measurements per second . So we are talking again about 1-3 data points from P7-P7.4 . Although I refer to the angular velocity of Kelli Oride's left arm velocity being perfectly matched to the angular velocity of her clubshaft between P7 => P7.4, that's not absolutely true. Note that she has a small degree of forward shaft lean at impact which means that her clubshaft can travel slightly faster than her lead arm between P7 => P7.2 without it overtaking her lead arm from an angular rotational perspective. That fact is even more true for DHers who have a markedly bowed lead wrist at impact (eg. Collin Morikawa) and where there is even more forward shaft lean. They can have even more angular velocity of their clubshaft happening between P7 => P7.2 (relative to their lead arm) without it overtaking their lead arm (from an angular rotational perspective). Also, judging whether the clubshaft is significantly overtaking the lead arm between P7 => P7.2 (from an angular rotational perspective) by looking at 2D images is imprecise because of the problem of parallax error. My definition of a DH-hand release action is not meant to be that precise, and I really expect that the lead wrist is extending by a few degrees in DHers without it being easily discernible in 2D images. The tour average of lead wrist extension is 6 degrees between P7 => P7.2 and that includes non-DHers. It is possible that DHers are closer to 3 degrees. Jeff.
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Post by dubiousgolfer on Jul 31, 2021 22:08:09 GMT -5
Many thanks Dr Mann Strangely enough I noticed another Kinematic graph on the golfsciencelab website using something called the K-Vest (although I haven't got a clue what the frequency is) . You can see that the actual clubhead speed drops dramatically post impact to even below the arm-speed. golfsciencelab.com/kinematic-sequence/DG
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Post by imperfectgolfer on Aug 2, 2021 11:43:47 GMT -5
Dr Mann If they were aligned on top of each other (or at the moment they cross each other) , that would mean the lead arm and club were rotating together like a fixed rigid object (ie. fixed angle between lead arm and club shaft). If the blue line is above the brown line and the distance between them increases (for any moment in time during the downswing) that means the angle between the lead arm and club shaft is decreasing. If the blue line is above the brown line and the distance between them decreases (for any moment in time during the downswing) that means the club shaft rotation is catching up with the lead arm rotation . This means the angle between the lead arm and club shaft is increasing which signifies a casting movement. This is what Phil Cheetham says in his document: ---------------------------- Let’s put three examples side by side and examine the relationships of each of the four curves during the downswing phase. From the graphs above it can be seen that “Pro” has relatively smooth accelerations and decelerations with each subsequent segment’s speed peaking higher and later than the previous one. Notice also that the club’s speed peaks at impact and in fact is still going up at impact; this means that the club is still accelerating when it hits the ball. Amateur 1 shows lower speeds; poorer accelerations and decelerations; and the peaks are out of sequence with the arm peaking before the thorax. Amateur 2 has no decelerations of the pelvis and thorax before impact, but has a little deceleration of the arm (followed by a re-acceleration before impact). Both amateurs cast the club and it races ahead of the other body segments; this is evident from the fact that the brown curve is on top of the other curves. This casting action causes the club to peak early and even decelerate a little before impact loosing speed and power. In contrast notice the Pro curves; near the middle portion of the graph the arm (blue) is actually on top of the club (brown). This means that the wrist is cocking more just before release. This action will tend to allow more energy to be supplied to club release from the efficient use of the “stretch-shorten cycle” of the forearm muscles. Since the graphs are scaled equally you can see that the club speed of the pro at impact is higher than that of both amateurs. ------------------------ Although I don't think the difference in clubhead speed is solely due to some stretch-shorten cycle in the forearm muscles . I would suspect that the Pro creates a larger 'In Plane Mof' than the amateurs. This may also explain the residual positive hand couple that we see in some of the inverse dynamic graphs while the 'In Plane MOF ' becomes positive. What that residual positive hand couple may represent is the stopping action of the 'decrease' in the PA2 angle (increasing lead wrist-cock) just before release. Could it be that JBH is using PP1 pressure force differently to increase left hand wrist cock more than Rory in the early downswing and just before release? It could be that his PP1 pressure force is more across the club and that will increase the negative MOF in the early downswing and decrease the PA2 angle . Rory might still be applying PP1 in a more tangential direction to the lead hand path, therefore assisting the left hand/arm speed but creating less negative MOF and larger PA2 angle before release. DG Note this claim by Phil Cheetham. "Amateur 2 has no decelerations of the pelvis and thorax before impact, but has a little deceleration of the arm (followed by a re-acceleration before impact). Both amateurs cast the club and it races ahead of the other body segments; this is evident from the fact that the brown curve is on top of the other curves. This casting action causes the club to peak early and even decelerate a little before impact loosing speed and power. In contrast notice the Pro curves; near the middle portion of the graph the arm (blue) is actually on top of the club (brown). This means that the wrist is cocking more just before release. This action will tend to allow more energy to be supplied to club release from the efficient use of the “stretch-shorten cycle” of the forearm muscles. Since the graphs are scaled equally you can see that the club speed of the pro at impact is higher than that of both amateurs." He concludes that if the brown curve is on top of the blue graph in the early-mid downswing that it implies casting (premature release of PA#2). However, I am now questioning the legitimacy of that claim.
I think that his claim makes sense if the lead arm and clubshaft are traveling on exactly the same plane between P1 => P5.5. Consider Jamie Sadlowski's downswing action. Image 1 is at P4 and image 2 is at P5.
Note that both his lead hand and clubshaft are traveling on the same plane so if the clubshaft travels faster than the lead arm, then that would imply casting. Now, consider Dustin Johnson's downswing action. Image 1 is at P4 and image 4 is at P5.
Note that his lead hand is coming steeply down the hand arc path between P4 => P5, but his clubshaft is shallowing a lot during that same time period. Therefore, his clubshaft's path is less steeply downwards and it is traveling slightly more horizontally in a looping manner. I could imagine that it causes the length of his clubhead path to be longer between P4 => P5 than it would otherwise be if he did not shallow his clubshaft (like Jamie Sadlowski) - even if he maintained exactly the same degree of lead wrist cocking. I wonder whether Phil Cheetham is taking that fact into full account! Jeff.
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Post by dubiousgolfer on Aug 2, 2021 12:28:44 GMT -5
Dr Mann
I was thinking the same because those Kinematic graphs are angular velocities in 3D and not all in one plane. I've assumed that Phil Cheetham is aware of that but your correct , he could be making an assumptions without looking at the detail of other 3D graphs for the specific players (ie. showing lead wrist ulnar-radial deviations and flexion/extension).
DG
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Post by dubiousgolfer on Aug 2, 2021 19:45:50 GMT -5
Dr Mann Here is JB Holmes Kinematic Sequence graph and his lead wrist graph (emailed to you by Jon Sinclair) All we'd need is JBH lead wrist radial-ulnar deviation graph which unfortunately was blocked by Phil Cheetham's image below. If we had that graph we might be able to actually confirm whether the blue line being above the brown line in the kinematic graph actually means a decrease in the PA2 angle (ie. pure increase in radial deviation) or a decrease in angle between club and lead arm due to increased lead wrist extension. Looking at the above graph it seems to suggest that JBH is extending his wrist somewhat , then suddenly increasing flexion before PA#2 release. DG
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Post by imperfectgolfer on Aug 2, 2021 22:00:50 GMT -5
DG,
You wrote-: "If we had that graph we might be able to actually confirm whether the blue line being above the brown line in the kinematic graph actually means a decrease in the PA2 angle (ie. pure increase in radial deviation) or a decrease in angle between club and lead arm due to increased lead wrist extension."
I cannot understand how increased lead wrist extension can cause the blue line to be above the brown line because lead wrist extension is operating in a plane that is at right angles to the plane of release of PA#2.
Jeff.
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Post by dubiousgolfer on Aug 3, 2021 7:24:27 GMT -5
DG, You wrote-: " If we had that graph we might be able to actually confirm whether the blue line being above the brown line in the kinematic graph actually means a decrease in the PA2 angle (ie. pure increase in radial deviation) or a decrease in angle between club and lead arm due to increased lead wrist extension." I cannot understand how increased lead wrist extension can cause the blue line to be above the brown line because lead wrist extension is operating in a plane that is at right angles to the plane of release of PA#2. Jeff. Dr Mann Yes , your correct , lead wrist extension/flexion won't impact the PA2 angle (just tried doing it myself). Also if one was retaining the PA2 angle plus adding wrist flexion/extension or forearm supination/pronation , won't that increase the net angular velocity of the club from a 3D perspective? Further, I would have thought the net angular velocity of the club in space would have to include angular velocity components (not in the same plane as the lead arm) made by other body movements . What about internal/external rotation of the whole lead and trail arm, could that also affect components of club shaft angular velocity perpendicular to the lead arm swing plane? The net angular velocity of the club would then probably be larger than the lead arm and the brown graph would be above the blue one . Therefore , you are correct in your previous post that the brown graph being above the blue (in transition or early downswing) might not necessarily be a casting action. DG
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Post by dubiousgolfer on Jun 27, 2023 21:15:58 GMT -5
Dr Mann
The kinetic sequence graphs that we've seen posted on previous threads has one important flaw. The arm graph is only the angular velocity of the upper arm therefore it won't be showing the angular velocity of the forearm if a golfer bends his lead arm in the downswing. Therefore one cannot identify the real velocity of the 'arm' or the PA2# point of release unless the golfer had a straight lead arm.
Apparently AMM3D does have forearm angular velocity graphs but I've never seen them published.
DG
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Post by imperfectgolfer on Jun 27, 2023 21:51:48 GMT -5
Dr Mann The kinetic sequence graphs that we've seen posted on previous threads has one important flaw. The arm graph is only the angular velocity of the upper arm therefore it won't be showing the angular velocity of the forearm if a golfer bends his lead arm in the downswing. Therefore one cannot identify the real velocity of the 'arm' or the PA2# point of release unless the golfer had a straight lead arm. Apparently AMM3D does have forearm angular velocity graphs but I've never seen them published. DG I do not know of any pro golfer who bends his lead elbow in the downswing to such a degree that it will cause the angular velocity of the lead forearm to be significantly different to the angular velocity of the lead upper arm. Jeff.
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Post by dubiousgolfer on Jun 28, 2023 3:53:44 GMT -5
Dr Mann The kinetic sequence graphs that we've seen posted on previous threads has one important flaw. The arm graph is only the angular velocity of the upper arm therefore it won't be showing the angular velocity of the forearm if a golfer bends his lead arm in the downswing. Therefore one cannot identify the real velocity of the 'arm' or the PA2# point of release unless the golfer had a straight lead arm. Apparently AMM3D does have forearm angular velocity graphs but I've never seen them published. DG I do not know of any pro golfer who bends his lead elbow in the downswing to such a degree that it will cause the angular velocity of the lead forearm to be significantly different to the angular velocity of the lead upper arm. Jeff. JB Holmes has a bent lead elbow at P4 and straightens it by P5.5 which means the angular velocity of his forearm increased more than his upper arm before PA2# release. DG
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Post by imperfectgolfer on Jun 28, 2023 8:27:40 GMT -5
I do not know of any pro golfer who bends his lead elbow in the downswing to such a degree that it will cause the angular velocity of the lead forearm to be significantly different to the angular velocity of the lead upper arm. Jeff. JB Holmes has a bent lead elbow at P4 and straightens it by P5.5 which means the angular velocity of his forearm increased more than his upper arm before PA2# release. DG I think that the amount of lead elbow bend is small and not significant. It would be significant if one used the Jack Kuykendall technique - where be bends his lead elbow to ~90 degrees at P4. Jeff.
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Post by dubiousgolfer on Jun 29, 2023 5:50:24 GMT -5
Dr Mann I think I've got a tenuous idea how the upper body pivot can pull the lead arm around in the early downswing and it's not what I first theorised but does involve some passive tissue interaction with the upper arm and chest area. When I first looked at Dave Tutelman's image on his website, I misinterpreted what he meant by the pushing of the chest on the lead upper arm. I thought he meant the chest was pushing the upper arm about the shoulder socket (ie. shoulder socket acting as some pivot point) but that seems incorrect. Firstly, do you agree that at P4 , there is some 'passive tissue interaction' high up in the left upper arm (very close to the shoulder socket) where its tissues press against the tissues of the left upper extremities in the pectoral area? DG
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Post by imperfectgolfer on Jun 29, 2023 9:08:14 GMT -5
Dr Mann I think I've got a tenuous idea how the upper body pivot can pull the lead arm around in the early downswing and it's not what I first theorised but does involve some passive tissue interaction with the upper arm and chest area. When I first looked at Dave Tutelman's image on his website, I misinterpreted what he meant by the pushing of the chest on the lead upper arm. I thought he meant the chest was pushing the upper arm about the shoulder socket (ie. shoulder socket acting as some pivot point) but that seems incorrect. Firstly, do you agree that at P4 , there is some 'passive tissue interaction' high up in the left upper arm (very close to the shoulder socket) where its tissues press against the tissues of the left upper extremities in the pectoral area? DG No - in response to your bold-highlighted question. I think that there is not a very close physical connection between the tissues of the lead upper arm and the lead anterior chest wall in pro golfers because of scapular protraction. Here is Rory McIlroy's driver swing.
The yellow circular marker shows the position of his lead humeral head and I think that it is positioned far enough away from his anterior chest wall due to lead scapular protraction, that there is no significant compression of the tissues of the upper arm against the anterior chest wall.
Jeff.
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Post by dubiousgolfer on Jun 29, 2023 9:58:21 GMT -5
Dr Mann I think I've got a tenuous idea how the upper body pivot can pull the lead arm around in the early downswing and it's not what I first theorised but does involve some passive tissue interaction with the upper arm and chest area. When I first looked at Dave Tutelman's image on his website, I misinterpreted what he meant by the pushing of the chest on the lead upper arm. I thought he meant the chest was pushing the upper arm about the shoulder socket (ie. shoulder socket acting as some pivot point) but that seems incorrect. Firstly, do you agree that at P4 , there is some 'passive tissue interaction' high up in the left upper arm (very close to the shoulder socket) where its tissues press against the tissues of the left upper extremities in the pectoral area? DG No - in response to your bold-highlighted question. I think that there is not a very close physical connection between the tissues of the lead upper arm and the lead anterior chest wall in pro golfers because of scapular protraction. Here is Rory McIlroy's driver swing.
The yellow circular marker shows the position of his lead humeral head and I think that it is positioned far enough away from his anterior chest wall due to lead scapular protraction, that there is no significant compression of the tissues of the upper arm against the anterior chest wall.
Jeff.
If there is no significant compression, what stops the lead arm from continuing in its backswing movement? I can hold my lead arm straight in front of me and lift it until its vertical when there is no tissue compression interaction, but why can't I do the same in a golf swing when the lead arm is partially horizontally adducted? Should I try not to have any tissue compression and just allow a freewheeling arm movement where in the backswing my upper arm reaches under my chin area (like Rory image below)? So does Logan Aldridge not use tissue interaction in his downswing? DG
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Post by imperfectgolfer on Jun 29, 2023 11:11:57 GMT -5
No - in response to your bold-highlighted question. I think that there is not a very close physical connection between the tissues of the lead upper arm and the lead anterior chest wall in pro golfers because of scapular protraction. Here is Rory McIlroy's driver swing. The yellow circular marker shows the position of his lead humeral head and I think that it is positioned far enough away from his anterior chest wall due to lead scapular protraction, that there is no significant compression of the tissues of the upper arm against the anterior chest wall. Jeff.
If there is no significant compression, what stops the lead arm from continuing in its backswing movement? I can hold my lead arm straight in front of me and lift it until its vertical when there is no tissue compression interaction, but why can't I do the same in a golf swing when the lead arm is partially horizontally adducted? Should I try not to have any tissue compression and just allow a freewheeling arm movement where in the backswing my upper arm reaches under my chin area (like Rory image below)? So does Logan Aldridge not use tissue interaction in his downswing? DG I can see no tissue interaction in Logan Aldridge's early downswing. Even if there is a small amount of soft tissue compression happening in the transition, I do not believe that it is a significant factor affecting the release of PA#4. In a two-handed golfer, the trail arm/hand can be used to set a limit to the degree of lead arm adduction that happens at P4. You asked-: " I can hold my lead arm straight in front of me and lift it until its vertical when there is no tissue compression interaction, but why can't I do the same in a golf swing when the lead arm is partially horizontally adducted?" I suspect that many shoulder girdle muscles become stretched when the lead arm is adducted thereby limiting the full range of lead arm elevation. Jeff.
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