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Post by imperfectgolfer on Nov 30, 2019 11:07:18 GMT -5
My downswing chapter was last revised in 2012 and there are many erroneous opinions of mine in that downswing chapter that need to be revised. Consider this kinematic sequence graph that I posted in that downswing chapter.
Note that the left arm travels at the same rotational speed as the shoulders (upper torso) until the upper torso slows down, and then it travels at the same degree of acceleration (same slope) until it eventually slows down. That graph implies that the speed of left arm motion (speed of release of PA#4) is dictated by the speed of upper torso rotation, which seemingly implies that the upper torso's rotation passively pulls the left arm along until the left arm eventually leaves the chest wall.
I also made a number of wrongheaded associated statements as follows-: "At the end of the backswing, these mid-upper torso muscles are optimally stretched, and they contract very forcefully in the early downswing thereby causing the upper torso to rotate very fast in the early/mid downswing. When these actively contracting mid-upper torso muscles shorten, they can no longer produce much energy and the upper torso rotation naturally/automatically decelerates during the later phase of the mid-downswing. When the upper torso decelerates, the left arm can freewheel away from the chest wall towards impact at a faster speed because there is no impedance to the freewheeling movement of the left arm away from the chest wall".
I presently (in 2019) believe that the speed of release of PA#4 can be significantly determined by the degree of contraction of the left-and-right shoulder girdle muscles - rather than the speed of upper torso rotation.
Let's compare two pro golfers who have similar "average driving distances" - Rickie Fowler (303 yards) and Jon Rahm (305 yards).
Here are face-on capture images of Rickie Fowler's early-mid downswing.
Image 1 is at P4, image 2 is at P5 and image 3 is at P5.5.
I have drawn colored rings over his left shoulder socket to show the degree of targetwards motion of the left shoulder socket between P4 and P5.5. RF has an upper torso rotation of 138 degrees at P4, which explains why he has such a large amount of left shoulder motion happening between P4 and P5.5. Theoretically, one could imagine that the large amount of left shoulder motion happening between P4 and P5.5 is very conducive to a very efficient release of PA#4 and a large degree of left hand speed by P5.5. However, note that his hands are about 12" outside his right thigh at P5.5 and there has not been much left arm motion happening in the plane of left arm adduction => abduction between P4 and P5.5.
Now, consider Jon Rahm's early-mid downswing action.
Image 1 is at P4, image 2 is at P5 and image 3 is at P5.5. I have drawn colored rings over his left shoulder socket to show the degree of targetwards motion of the left shoulder socket between P4 and P5.5. JR only has 78 degrees of upper torso rotation at P4, and he therefore has far less left shoulder socket travel happening between P4 and P5.5. However, note that he also has his hands about 12" outside his right thigh at P5.5, and most of the left hand motion has been downwards, rather than targetwards, between P4 and P5.5.
If one presumes that the speed of release of PA#4 correlates with left hand speed at P5.5, then it may be that RF and JR have similar left hand speeds at P5.5. The difference could be that JR gets most of his left hand speed at P5.5 as a result of the contraction of his shoulder girdle muscles (left + right) and not due to his speed of upper torso rotation.
As a reminder, here is Jon Rahm's kinematic sequence graph.
Top = start of the downswing. Note that the blue graph (left arm velocity graph) has a steeper slope than the green graph (upper torso velocity graph) from the very start of the downswing suggesting that the left arm is not being passively pulled along by the rotating upper torso.
Jeff.
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Post by imperfectgolfer on Nov 30, 2019 11:34:53 GMT -5
Another point of contention is when does PA#4 actually start to release. Here is an image from the TGM book. Note that the degree of release of PA#4 is referenced relative to a line drawn across the chest between the two shoulder sockets. That implies that if the distance between the hands and the right shoulder does not increase in the plane of left arm adduction => abduction during the early downswing that PA#4 is still fully loaded, and not yet released. Here is Rickie Fowler's early-mid downswing action - as viewed from DTL. Image 1 is at P4, image 2 is at P5 and image 3 is at P5.5. The angle between the left arm and chest wall may not have significantly changed in the plane of left arm adduction => abduction between P4 and P5.5, but the left hand has moved significantly in space during that time period. Does that amount of left hand motion between P4 and P5 represent the release of PA#4, or not? Here is Jon Rahm's early-mid downswing - as viewed from DTL.
Note that the amount of left hand travel (in the vertical plane) between P4 and P5 is similar to that of RF.
Note that there has been very little left arm motion happening in the plane of left arm adduction => abduction between P4 and P5. Does that amount of left hand motion between P4 and P5 represent the release of PA#4, or not? Jeff.
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Post by syllogist on Dec 1, 2019 8:46:27 GMT -5
Dr. Mann,
Personally, I prefer to stay away from comparing tour pros and presuming what they are doing based on not only a limited number of photos but also on digital sensor analysis. The graph you posted shows torso and left arm at the same speed and then the left arm begins to acquire greater speed. I do believe that the left arm is "passive" and does not (or rather should not) move toward abduction via an "active" muscular effort ...
... The straightening of the right arm results in "hand travel," which is "incidental" left arm abduction. The early rotational inertia of the club from the rotation of the torso/left arm unit, places a torque on the right arm, which acts on it and begins to unbend it.
The above is not to say that any given tour pro doesn't do something to interfere with the sole objective of making the club forcefully rotate "end over end" during the second half of the downswing. I can't possibly know the precise reasons why JR and RF exhibit somewhat different PA 4 "release" tendencies but I do believe that both exhibit the "essence" of the swing. To analyze such difference between the two might be "splitting hairs."
I don't view Kelley's PA 4 as he did. The torso begins to decelerate (or requires more rotational force not to decelerate) as the left arm/club unit separates from the torso and the left arm decelerates well after torso deceleration, during release. In other words, if the torso decelerates before the left arm, then there is "release" of PA 4. The left arm does not literally "blast off" the chest. However, it does acquire its speed from the torso.
S
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Post by dubiousgolfer on Dec 1, 2019 9:55:13 GMT -5
I always thought the releasing of PA#4 using an active pivot meant that the 'Release' aspect was in a plane of left arm adduction=> abduction (ie. perpendicular to the upper pivot's axis of rotation). Say the golfer was standing erect, it would be similar to the transverse plane in the image below but moved up to a line across the shoulder sockets. Therefore an active pivot to release PA#4 would cause the left arm to traverse that 'transverse'plane. But for that erect posture above , what about the vertical aspect of the left arm movement (ie. in the Coronal plane)? If PA#4 release is defined as above within the 'transverse plane' then it cannot be solely used to define the vertical element of the left arm movement. So should one be using PA#5 rather than PA#4 for the powering of the swing from P4-P5.5? Or maybe add another PA for the left arm downward movement caused by the left shoulder girdle muscular contractions? DG
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Post by imperfectgolfer on Dec 1, 2019 10:22:01 GMT -5
Dr. Mann, Personally, I prefer to stay away from comparing tour pros and presuming what they are doing based on not only a limited number of photos but also on digital sensor analysis. The graph you posted shows torso and left arm at the same speed and then the left arm begins to acquire greater speed. I do believe that the left arm is "passive" and does not (or rather should not) move toward abduction via an "active" muscular effort ... ... The straightening of the right arm results in "hand travel," which is "incidental" left arm abduction. The early rotational inertia of the club from the rotation of the torso/left arm unit, places a torque on the right arm, which acts on it and begins to unbend it. The above is not to say that any given tour pro doesn't do something to interfere with the sole objective of making the club forcefully rotate "end over end" during the second half of the downswing. I can't possibly know the precise reasons why JR and RF exhibit somewhat different PA 4 "release" tendencies but I do believe that both exhibit the "essence" of the swing. To analyze such difference between the two might be "splitting hairs." I don't view Kelley's PA 4 as he did. The torso begins to decelerate (or requires more rotational force not to decelerate) as the left arm/club unit separates from the torso and the left arm decelerates well after torso deceleration, during release. In other words, if the torso decelerates before the left arm, then there is "release" of PA 4. The left arm does not literally "blast off" the chest. However, it does acquire its speed from the torso. S, I cannot understand your perspective - especially regarding the bold-highlighted statement. PA#4 is released in the early downswing when both the upper torso and left arm are still accelerating. I also cannot fathom why you would believe that Jon Rahm gets his left arm speed from the rotating torso - considering the fact that his left arm is traveling faster than his upper torso from the very start of the downswing. DG, I think that it makes no sense to postulate a need for another PA to explain the downward component of the release of PA#4. The left arm only moves in one planar direction during the early-mid downswing and its directional planar movement is intermediate between the transverse and coronal planes. It is also not rational to claim that the torso rotation (via the targetwards motion of the left shoulder socket) is only responsible for left arm motion in the transverse plane - because it can obviously also move the left arm downwards if the left arm starts at the 11 - 12 o'clock position at P4 and spinal bend inclination exists that tilts the transverse plan groundwards. I also do not believe that it is possible to clearly define the biomechanical cause of the downward component of the PA#4 release phenomenon because it could be from torso rotation and/or from shoulder girdle muscle contraction.
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Post by syllogist on Dec 1, 2019 11:54:09 GMT -5
Dr. Mann,
It depends on at what point in the downswing one is referring to. In the early downswing, the left arm can accelerate faster than the torso if forces act on the right arm to begin to straighten it. In the later downswing, the torso decelerates before the left arm does. Of course one can also choose to accelerate the left arm actively while accelerating the torso. However, the amount of force that one can actively apply through a joint is limited when the joint is in motion, especially the faster the joint moves through space. If JR's technique is to actively and independently accelerate his left arm with meaningful force from the top (which cannot be proven unless we were able to ask him), his torso rotational speed may be adversely affected.
What this all boils down to is that if two tour pros have the same clubhead speed and their techniques are substantially similar then, by and large, the force they both apply during the start down is similar. If you believe that one actively and independently accelerates the left arm while the other one does so passively, and overall clubhead speed is the same, then the total force applied by both is still similar. It becomes a matter of which technique is more efficient and, as a matter of principle, the greater the efficiency, the less the required "effort."
Personally, I think it's more worthwhile to identify the general and substantial similarities of the tour pros in order to identify the "essence" of a good swing rather than to get caught up in what we may identify as differences and why those differences exist.
S
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Post by dubiousgolfer on Dec 1, 2019 12:10:49 GMT -5
Dr Mann - Yes , now I see . Once spinal bend inclination, the transverse plane also tilts downward . Therefore a component of that 'downwards' motion of the left arm as seen from a DTL view could be caused by the movement of the left shoulder socket. So how can one define Jon Rahms swing? Is he more a 'Right Arm swinger' (Barrel sequence 5:2) rather than a TGM Swinger ( 4:2 )? I've left out 3 because that is a club squaring accumulator. DG PS. With regards your question "Does that amount of left hand motion between P4 and P5 represent the release of PA#4, or not?" I think that your statement above makes more sense than the TGM photo image below. I've never read the TGM book so wondering whether Homer thought that the left pec pushed the left upper arm around (ie. connection). Was he thinking about that scenario when he developed the PA#4 concept?
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Post by syllogist on Dec 1, 2019 14:26:47 GMT -5
Hi DG,
This is not to say that one cannot perform any combination of muscular actions in a swing, but the following exercise may provide some insight. It also might dispel the notion of left side vs. right side techniques and introduce that the swing just may be the "arms" as a whole.
Stand erect. Rotate torso clockwise 90 degrees. Cock wrists and fully adduct the left arm horizontally. Swing counterclockwise horizontally by rotating torso and left arm as a unit. Take notice of the forces acting on the arms and how PA 4 releases and the right arm experiences straightening. Take notice of when they happen. Do the same but physically stop the movement of the arms 45 degrees into your counterclockwise rotation. Take notice of the effort necessary to stop the arms. Even before your wrists had the opportunity to release, didn't the inertia of the club act on your arms to cause you effort to stop them?
The left arm/club unit becomes "heavy" as inertia increases. There is no need to force the movement of the left arm via muscular effort.
S
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Post by imperfectgolfer on Dec 1, 2019 16:39:48 GMT -5
DG,
I coined the term PA#5" with respect to an active right arm adduction maneuver and I only use that term to describe a right arm swinging action that is entirely powered by P#5, and not PA#4. A TGM swinging action's PA#4 release phenomenon can be powered by various combinations of i) upper torso rotation moving the left shoulder socket that secondarily pulls the left arm; ii) left shoulder girdle muscles and iii) right shoulder girdle muscles. I think that Jon Rahm is a TGM swinger who probably uses a disproportionately large amount of iii).
Jeff.
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Post by imperfectgolfer on Dec 1, 2019 16:49:05 GMT -5
S, You wrote-: " In the early downswing, the left arm can accelerate faster than the torso if forces act on the right arm to begin to straighten it." I don't understand why you believe that right arm is straightening is needed in the early downswing to cause the left arm to accelerate faster than the torso. Jon Rahm's 3-D graph shows that his left arm travels faster than his upper torso between P4 and P5.5, but he has no right arm straightening during that time period. Image 1 is at P4 and image 4 is at P5.5, and I do not see any right arm straightening action between P4 and P5.5. Jeff.
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Post by dubiousgolfer on Dec 1, 2019 18:59:24 GMT -5
DG, I coined the term PA#5" with respect to an active right arm adduction maneuver and I only use that term to describe a right arm swinging action that is entirely powered by P#5, and not PA#4. A TGM swinging action's PA#4 release phenomenon can be powered by various combinations of i) upper torso rotation moving the left shoulder socket that secondarily pulls the left arm; ii) left shoulder girdle muscles and iii) right shoulder girdle muscles. I think that Jon Rahm is a TGM swinger who probably uses a disproportionately large amount of iii). Jeff. Many thanks for that clarification Dr Mann But I still cannot easily reconcile your 2 paragraphs below to explain how his active pivot is mostly responsible for the efficient inducement of release of PA#4 while the graph shows left arm moving with greater angular velocity than thorax (assuming 'thorax' angular velocity is equivalent to his left shoulder socket's angular velocity). "This observation suggests to me that his left arm's downward motion at the start of his downswing is mainly being powered by his shoulder girdle muscles (both right and left) that are both causally responsible for moving the left arm in a mainly downwards direction between P4 and P5.25 (as seen in Jon Rahm's hand arc path image) and that it is not primarily due to the pivot action's counterclockwise rotation of the upper torso that passively pulls the left arm around the body via the left arm's connection to the upper torso at the left shoulder socket. It also suggests to me that the peak speed of his left arm motion (which probably happens at ~P5.5) will probably better correlate with the efficiency/speed of contraction of his shoulder girdle muscles rather than the efficiency/speed of rotation of his pelvis and upper torso.""Going back to my analysis of Jon Rahm's golf swing, I agree with Greg Rose who believes that Jon Rahm is using an active pivot action and that his active pivot action is mostly responsible for powering his driver golf swing action by efficiently inducing the release of PA#4. I also think that Jon Rahm is using an active right arm adduction maneuver to more efficiently speed-up the vertical (downwards) component of his PA#4 release action between P4 and P5.5."DG
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Post by imperfectgolfer on Dec 1, 2019 23:35:42 GMT -5
DG, I coined the term PA#5" with respect to an active right arm adduction maneuver and I only use that term to describe a right arm swinging action that is entirely powered by P#5, and not PA#4. A TGM swinging action's PA#4 release phenomenon can be powered by various combinations of i) upper torso rotation moving the left shoulder socket that secondarily pulls the left arm; ii) left shoulder girdle muscles and iii) right shoulder girdle muscles. I think that Jon Rahm is a TGM swinger who probably uses a disproportionately large amount of iii). Jeff. Many thanks for that clarification Dr Mann But I still cannot easily reconcile your 2 paragraphs below to explain how his active pivot is mostly responsible for the efficient inducement of release of PA#4 while the graph shows left arm moving with greater angular velocity than thorax (assuming 'thorax' angular velocity is equivalent to his left shoulder socket's angular velocity). "This observation suggests to me that his left arm's downward motion at the start of his downswing is mainly being powered by his shoulder girdle muscles (both right and left) that are both causally responsible for moving the left arm in a mainly downwards direction between P4 and P5.25 (as seen in Jon Rahm's hand arc path image) and that it is not primarily due to the pivot action's counterclockwise rotation of the upper torso that passively pulls the left arm around the body via the left arm's connection to the upper torso at the left shoulder socket. It also suggests to me that the peak speed of his left arm motion (which probably happens at ~P5.5) will probably better correlate with the efficiency/speed of contraction of his shoulder girdle muscles rather than the efficiency/speed of rotation of his pelvis and upper torso.""Going back to my analysis of Jon Rahm's golf swing, I agree with Greg Rose who believes that Jon Rahm is using an active pivot action and that his active pivot action is mostly responsible for powering his driver golf swing action by efficiently inducing the release of PA#4. I also think that Jon Rahm is using an active right arm adduction maneuver to more efficiently speed-up the vertical (downwards) component of his PA#4 release action between P4 and P5.5."DGYes - that's a contradiction that needs explanation. I now disagree with my 2nd statement where I stated that I agree with Greg Rose that his pivot action is the primary factor causing JR's release of PA#4. I suspect that he gets a lot of the swing power required for a fast release of PA#4 from his shoulder girdles muscles (left + right). I know of no scientific method that can help me quantify how much swing power is derived from his pivot motion versus the amount derived from the muscular contraction of his shoulder girdle muscles. Jeff.
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Post by syllogist on Dec 2, 2019 5:02:14 GMT -5
Hi Dr. Mann, Regarding the most recently posted Rahm photo stills, it would take quite an ingenious protractor to figure out how much right arm straightening occurred between P4 and P5.5. I didn't state that right arm straightening is necessary to have the left arm accelerate faster than the torso but, rather, can cause such. Refer to the three Rahm stills you posted from a down-the-line view to make a presumption about how much straightening occurred. S
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Post by imperfectgolfer on Dec 2, 2019 10:15:59 GMT -5
Hi Dr. Mann, Regarding the most recently posted Rahm photo stills, it would take quite an ingenious protractor to figure out how much right arm straightening occurred between P4 and P5.5. I didn't state that right arm straightening is necessary to have the left arm accelerate faster than the torso but, rather, can cause such. Refer to the three Rahm stills you posted from a down-the-line view to make a presumption about how much straightening occurred. S I don't need an "ingenious protractor" to measure how much the right arm straightens between P4 and P5.5 in skilled pro golfers because it is obviously not a significant amount - as can be seen in these face-on images of Jamie Sadlowski's and Dustin Johnson's and Jon Rahm's downswing. Jamie Sadlowski
Dustin Johnson
Jon Rahm
If right arm straightening between P4 and P5.5 is not a necessary requirement to cause the left arm to accelerate faster than the torso in the early-mid downswing, then why do you bring it up as a potential consideration? I think that right arm straightening in the early downswing is a major swing fault!
Jeff.
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Post by imperfectgolfer on Dec 2, 2019 10:36:27 GMT -5
I am increasingly inclined to modify my personal (non-TGM) definition of a PA#4 release action where I define the start of the release of PA#4 as happening when the hands first start to move from its P4 position. Here is Jamie Sadlowski's PA# 4 release action.
Image 1 is at P4 and image 2 is at P4.5. I previously thought that PA#4 is not being released between P4 and P4.5 because the left arm has not changed its degree of adduction against the chest wall during that time period. However, the hands are definitely moving away from its P4 location and hand speed is starting to be generated. I now think that it may be better to include that time period in the definition of a PA#4 release action. I also now think that when considering the forces that cause the release of PA#4 (release of the left arm) that one should include all potential biomechanical forces - i) motion of the left shoulder socket pulling the left humeral head along; ii) left shoulder girdle muscles pulling the left arm downwards; iii) right shoulder girdle muscles adducting the intact "right upper arm + RFFW" unit in a downwards direction.
Jeff.
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