|
Post by dubiousgolfer on Mar 24, 2024 19:50:43 GMT -5
Dr Mann
Have you seen this new video ?
DG
|
|
|
Post by imperfectgolfer on Mar 24, 2024 23:50:44 GMT -5
Dr Mann Have you seen this new video ? DG DG, This video seems to just be a continuation of the argument that the AMG instructors had with Milo Lines. The major difference is that they have presented their argument with amazingly good quality graphics that shows the motion of the spine in much clearer detail. There is nothing in the video that has changed my thinking about how the spine moves in the backswing and downswing. However, there is one questionable claim that MG makes at the 12:15 minute time point of the video where he claims that both the lower body and upper body are moving upwards at P5. How is that possible? I think that if the head drops groundwards between P4 => P5 in Rory McIlroy's early downswing due to increased hip joint flexion - then I cannot understand how MG's claim can be legitimate. I also do not understand why MG claims that he (MG) and SW "blew-out their back" (? herniated their lumbar discs) due to a wrongheaded attempt to get a lot of right-sided lateral bend in their early downswing. Jeff.
|
|
|
Post by dubiousgolfer on Mar 25, 2024 7:13:21 GMT -5
Dr Mann
I couldn't make sense about the lower and upper body moving upwards either.
DG
|
|
|
Post by imperfectgolfer on Mar 25, 2024 9:21:41 GMT -5
Dr Mann I couldn't make sense about the lower and upper body moving upwards either. DG One person asked that question in the comments section. MG replied as follows-: " As for the lowering, which is a great question/topic BTW, let me ask you this… these players lower the most in their backswings as their spines are extending - thinking in 3D, what do you think allows that to happen, then the opposite in the downswing?" That's a very unsatisfactory reply that does not answer the question. Jeff.
|
|
|
Post by dubiousgolfer on Mar 25, 2024 12:43:01 GMT -5
Dr Mann I couldn't make sense about the lower and upper body moving upwards either. DG One person asked that question in the comments section. MG replied as follows-: " As for the lowering, which is a great question/topic BTW, let me ask you this… these players lower the most in their backswings as their spines are extending - thinking in 3D, what do you think allows that to happen, then the opposite in the downswing?" That's a very unsatisfactory reply that does not answer the question. Jeff. Maybe he really doesn't know the answer.
|
|
|
Post by dubiousgolfer on Mar 25, 2024 13:49:16 GMT -5
If you read the youtube comments, someone else asked the same question and AMG's reply was: ""The gist is - the centers move down the most in the backswing. Lower just a small amount more (~3/8”) very early in downswing then are in the way up from lead arm parallel down." But that claim doesn't seem to match what is found on another 3D system called AMM which uses inertial sensors rather than GEARS optical sensors . Here are Dr Phil Cheetham's graphs for pelvis up and down movement (Drop and Lift). The graphs from AMM3D shows the pelvis, on average, dropping 1.2 inches max in the downswing (3.8 inches for long drivers). But where in the swing does this max pelvis downward motion happen? Is it at P5 , lead arm parallel as per GEARS 3D? I haven't seen AMM3D chest up and down graphs on any Sportsbox videos, so I can't compare with AMG GEARS 3D data claims. DG
|
|
|
Post by imperfectgolfer on Mar 25, 2024 14:15:58 GMT -5
If you read the youtube comments, someone else asked the same question and AMG's reply was: ""The gist is - the centers move down the most in the backswing. Lower just a small amount more (~3/8”) very early in downswing then are in the way up from lead arm parallel down." But that claim doesn't seem to match what is found on another 3D system called AMM which uses inertial sensors rather than GEARS optical sensors . Here are Dr Phil Cheetham's graphs for pelvis up and down movement (Drop and Lift). The graphs from AMM3D shows the pelvis, on average, dropping 1.2 inches max in the downswing (3.8 inches for long drivers). But where in the swing does this max pelvis downward motion happen? Is it at P5 , lead arm parallel as per GEARS 3D? I haven't seen AMM3D chest up and down graphs on any Sportsbox videos, so I can't compare with AMG GEARS 3D data claims. DG Increased knee joint flexion that can happen during the hip-squaring phase's squat move between P4 => P5 can cause a small amount of pelvic drop. However, I think that one should not only be looking at pelvis drop/lift. For example, if a golfer develops increased anterior pelvic tilt due to increased hip joint flexion, then the head and upper swing center can drop due to a change in the spinal bend inclination angle without any pelvic drop. Rory McIlroy's head drop phenomenon Image 1 is at P1 - I have drawn a blue line along the top of his head. Image 2 is at P4 and image 3 is at P5. Note that his head drops a small amount between P1 => P4, but it drops a larger amount between P4 => P5 due to increased hip joint and knee flexion. Jeff.
|
|
|
Post by dubiousgolfer on Mar 25, 2024 16:32:55 GMT -5
Dr Mann
So looking at Rory's images above, couldn't he just be starting to extend his knees by P5? This could account for GEARS and AMM3D (who use the same spine algorithms) showing an upward movement of the pelvis/thorax.
DG
|
|
|
Post by imperfectgolfer on Mar 25, 2024 17:09:50 GMT -5
Dr Mann So looking at Rory's images above, couldn't he just be starting to extend his knees by P5? This could account for GEARS and AMM3D (who use the same spine algorithms) showing an upward movement of the pelvis/thorax. DG No. Lead knee extension starts slightly later and is first noted between P5.2 => P5.5 and then getting greater in degree between P5.5 => P7. It does not happen between P4 => P5. Maximum knee flexion happens at ~P5. Jeff.
|
|
|
Post by dubiousgolfer on Mar 25, 2024 17:22:45 GMT -5
Dr Mann So looking at Rory's images above, couldn't he just be starting to extend his knees by P5? This could account for GEARS and AMM3D (who use the same spine algorithms) showing an upward movement of the pelvis/thorax. DG No. Lead knee extension starts slightly later and is first noted between P5.2 => P5.5 and then getting greater in degree between P5.5 => P7. It does not happen between P4 => P5. Maximum knee flexion happens at ~P5. Jeff. Do you think AMM3D/GEARS spine and pelvic measurements are flawed? DG
|
|
|
Post by imperfectgolfer on Mar 25, 2024 22:11:14 GMT -5
No. Lead knee extension starts slightly later and is first noted between P5.2 => P5.5 and then getting greater in degree between P5.5 => P7. It does not happen between P4 => P5. Maximum knee flexion happens at ~P5. Jeff. Do you think AMM3D/GEARS spine and pelvic measurements are flawed? DG No. Have you seen any evidence that AMM3D/GEARS measurements show that the pelvis/chest elevate between P4 => P5? Jeff.
|
|
|
Post by dubiousgolfer on Mar 26, 2024 6:54:18 GMT -5
Do you think AMM3D/GEARS spine and pelvic measurements are flawed? DG No. Have you seen any evidence that AMM3D/GEARS measurements show that the pelvis/chest elevate between P4 => P5? Jeff. Dr Mann Here are some graphs from AMM3D of 3 pros (I don't know their names but I think they are PGA winners). Sorry for the blurriness but the red graph is Pelvis Drop/Lift , while the green graph is Thorax Drop/Lift. The scaling for the vertical axis is 1.3 inches (I think!). The pelvis drop for the bottom two pros seem insignificantly small compared to the thorax drop, but the top two seem to show pelvis/thorax lift by P5, while the bottom player might be delayed to P5.2-5.5 (unsure to be honest). DG
|
|
|
Post by imperfectgolfer on Mar 26, 2024 9:39:46 GMT -5
No. Have you seen any evidence that AMM3D/GEARS measurements show that the pelvis/chest elevate between P4 => P5? Jeff. Dr Mann Here are some graphs from AMM3D of 3 pros (I don't know their names but I think they are PGA winners). Sorry for the blurriness but the red graph is Pelvis Drop/Lift , while the green graph is Thorax Drop/Lift. The scaling for the vertical axis is 1.3 inches (I think!). The pelvis drop for the bottom two pros seem insignificantly small compared to the thorax drop, but the top two seem to show pelvis/thorax lift by P5, while the bottom player might be delayed to P5.2-5.5 (unsure to be honest). DG In the top graph, the vertical green line is at the nadir of the red graph which means that this is the point of maximum pelvic drop and it is just passed the nadir of the green graph. That means that the pelvis/thorax was significantly dropping between P4 => P5 and that no significant pelvis/thorax elevation happened between P4 => P5. In the middle graph, the pelvis graph shows no significant pelvis drop due to knee flexion so it is irrelevant as to when a small degree of pelvis lift starts. It is obvious that there is no significant amount of pelvic elevation happening between P4 => P5 and the slope of the red graph only starts to steepen well after P5. The vertical green line is at the nadir of the green graph and that means that no elevation of the thorax happened between P4 => P5, and that the thorax was dropping significantly groundwards between P4 => P5. In the bottom graph, the pelvis/thorax are still dropping at P5. Jeff.
|
|
|
Post by dubiousgolfer on Mar 26, 2024 11:13:12 GMT -5
The bottom 2 golfers haven't reached P5 yet when you look at the avatars, so the green vertical line may shift a little to the right but if there is any upwards movement it seems insignificant.
DG
|
|
|
Post by imperfectgolfer on Mar 28, 2024 10:51:43 GMT -5
I have been thinking a lot about the spinal motion measurements that MG presented in his latest AMG video and I am increasingly wondering whether they are scientifically valid/plausible. Consider these spinal motion measurements of Rory McIlroy at his P4 position. Note that it claims that RM's thoracic spine has rotated 67 degrees with ~30 degrees of side-bend to the left and that his thoracic spine is extended by ~23 degrees. I consider those measurements plausible. However, consider RM's spinal motion measurements at P5. Note that has still has 59 degrees of clockwise rotation of his thoracic spine and 30 degrees of side-bend to the left - which means that there has been essentially no significant change in those spinal motion measurements. However, he has flexed his thoracic spine by 45 degrees between P4 => P5. Do you believe that it is biomechanically plausible that RM can flex his thoracic spine by 45 degrees without changing his degree of thoracic spine rotation and side-bend to the left? Consider these overhead capture images of RM's P4 => P5 time period. Image 1 is at P4 and image 2 is at P5. It looks like his shoulders have rotated ~110 degrees at P4, and if his pelvis has rotated ~50 degrees then it is plausible that his thoracic spine has rotated ~60 degrees clockwise at P4. It is also plausible that his thoracic spine is extended by 23 degrees (due to performing an arch-extension maneuver in a targetwards direction) and that he has also simultaneously acquired ~30 degrees of side-bend of his thoracic spine to the left.
In image 2 he is at the P5 position, where he changed his degree of thoracic spine flexion by ~40 degrees so that his thoracic spine is ~20 degrees flexed at P5, which looks visually feasible in that P5-image. However, look at how much his shoulders have rotated counterclockwise between P4 => P5. Note that his pelvis is parallel (square) to the ball-target line at P5 and that his shoulders/upper torso is ~32 degrees closed relative to the ball-target line. When I used Photoshop to make that 32 degrees measurement I was aware that his trail shoulder is retracted at P4 and far more protracted at P5, and that his lead shoulder is equally protracted at P4 and P5, so I drew a measuring-line that is more parallel to his upper back. I am also aware that there is a difference in MG's P5 image and my P5 image (where the upper torso is rotated further counterclockwise) - but it is very difficult for me to believe that RM has not significantly changed his degree of thoracic spine rotation between P4 => P5. I also find it very difficult to believe that he still has 30 degrees of side-bend to the left in that overhead P5 image. Here are back-view images of RM's P4 => P5 time period. Image 1 is at P4, image 2 is at P4.3, image 3 is at P4.6 and image 4 is at P5. I find it plausible that RM's thoracic spine is 20 degrees flexed at P5, but I find it more difficult to believe that he still has 60 degrees of clockwise rotation of his thoracic spine plus 30 degrees of side-bend to the left at P5. Look at how much RM is flexing his upper back area between image 1 => image 4 - do you think that it is biomechanically possible to do that without him changing his degree of thoracic spine rotation and side-bend to the left? Also, consider what MG stated between the 12:13 - 12:33 minute time points of the video. He stated that the centers of the pelvis and chest are moving up, and not closer to the ground. How is that possible? I have made this animated gif of RM's P4 => P5 time period. It is very apparent to me that his lower swing center at pelvis level and his upper swing center at the level of his upper thoracic spine is moving down, and not up; and that his chest is getting closer to the ground. Now, consider this image of RM at his P6 position. Note that his pelvis is slightly open relative to the ball-target line while his shoulders/upper torso are minimally closed. However, MG claims that his thoracic spine is still ~36 degrees closed (= rotated clockwise) at P6. Look at RM's mid-upper thoracic spine area - does it look ~36 rotated clockwise relative to the ball-target line? The only area of his thoracic spine that looks like it could still rotated ~36 degrees clockwise in that spine image on the right is the area involving the upper three thoracic vertebra. That brings me to the fundamental question? How does MG measure thoracic spine rotation? It is my impression that MG uses the GEARS system to measure the rotational motion of a body part, but GEARS does not have a measurement for spinal motion as far as I know. Is he using rib cage motion to measure spinal motion? If he is using rib cage motion then how is he correctly inferring that it represents thoracic spinal motion where the degree of rotation of each thoracic vertebra varies and where the degree of rotation is far greater in amount between the T1 -T4 area of the T-spine compared to T8 - T12 of the T-spine? If I am correct to assume that MG's thoracic spine rotational measurements better reflect the degree of rotation of the T1-T4 area of the thoracic spine (upper spine area), then which part of the rib cage is he using to make his measurements? I would very much like to see MG explain in great detail how he is capable of accurately measuring the degree of rotation of the thoracic spine.
Jeff.
|
|