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Post by dubiousgolfer on Feb 27, 2017 10:14:38 GMT -5
If I had a camera that could continuously view the 'hand arc path' normal to the intact LFFW , the real hand path (imho) would look completely different to the path traced from a face-on view.
From a face-on view I've seen hand arc paths traced to show a more linear (greater radial curve) from 'top of the backswing' to the 'end of the early downswing'.
In reality that 'camera' would show a 'hand arc path' whose radius would be from the C7 joint to the hands . That is, if we retained PA4 intact and the hand distance from the right shoulder remained the same for that phase of the swing.
For the remainder of the swing , that camera would see a 'hand arc path' whose curvature radius would be progressively longer as the right arm extended into impact (distance from hands to C7 joint progressively increasing).
So imho, the real hand arc path is more curved by the end of the early downswing and getting less curved all the way to impact . This is the total opposite of the traced hand arc path one sees from a face-on view and seems to be (imho) an optical illusion.
So I'm finding it difficult to understand how the 'Endless Belt' and 'Aiming Point' concepts can be used correctly in the golf swing if the geometry is based on an optical illusion.
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Post by imperfectgolfer on Feb 27, 2017 18:43:32 GMT -5
I don't know why you refer to C7. What's its relevance?
I think that the face-on view reflects the hand arc path reasonably well in terms of straight line sections and more circular sections - considering the fact that it is a 2-D reflection of a 3-D phenomenon that is happening in a plane that is obviously not perpendicular to a face-on camera.
Jeff.
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Post by imperfectgolfer on Feb 28, 2017 0:46:38 GMT -5
See this video of Adam Scott's swing It allows one to trace his hub path. Here are capture images from the video. Point 1 is where his hub path is at P4. Point 2 is where his hub path is at P5. Note that the hub path is relatively straight, and not very circular, between point 1 and point 2. Point 3 is where his hub path is at P5.5. Note that the hub path is very "tightly" circular between point 2 and point 3. Point 4 is where his hub path is at P6. Note that the hub path is less "tightly" circular between point 3 and point 4. Point 5 is at impact. Note that the hub path is less "tightly" circular between point 4 and point 5. Look at the position of his C7 vertebra - which is roughly positioned above his sternal notch area (roughly midway between the two shoulder sockets) - and note that it is not near the center of an imaginary circle depicting either the hub path or the clubhead path. Note that the straightening right arm will not not affect the shape of the hub path in the sense that the hub path would likely have the same shape if he only swung with his left arm and if didn't use his right arm - presuming that he performs the same pivot motion and the same left shoulder socket motion and presuming that he releases PA#4 (left arm) with the same timing pattern. Jeff.
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Post by dubiousgolfer on Feb 28, 2017 9:46:10 GMT -5
Dear Dr Mann
Thanks for the reply but I am still confused.
With regards C7, I have read that a 'Stationary Head' was an 'Essential' (as per TGM) and is the 'centre of the pivot'.
Maybe I'm misinterpreting but I envisioned the phase of the early downswing to be an almost 'rigid' movement. Where the 'arms/club/shoulders' all move as one unit but rotating around the C7 (or Sternum Notch) centre of pivot. Therefore if you used the hands position as a reference point and measured its distance to the 'centre of pivot' , that would provide the radius of the early downswing phase.
I have assumed that the hands then move progressively away from the centre of pivot as the swing progresses from P2 -P6 and that the radius (distance from hands to centre of pivot) gets progressively longer (is that correct?).
Imho, you cannot just use a face-on view to track the real hub path because it is not 'normal' to the LFFW plane which could be changing its inclination with the ground during the downswing.
I did a simple experiment by drawing a circle on a piece of paper and then folding it (through the middle) so that it had a 120 degree angle between the 2 halves and then just placed it on a shelf (so that the top half was flat against a wall) and looked at it from a 'face on view'. It looked like the hand path seen on the Adam Scott video you posted above. The curvature you see from the face-on view is an optical illusion and cannot represent an 'endless belt' from a physics standpoint.
IMHO , the 'Law of the Flail' is a better representation of the golf swing.
Note: I've asked someone who has a 3D analysis tool to see if he can track the hand/hub path (of a high level golfer) from a 'normal to the LFFW plane' view. This should clear things up for me.
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Post by imperfectgolfer on Feb 28, 2017 23:47:29 GMT -5
Dear Dr Mann Thanks for the reply but I am still confused. With regards C7, I have read that a 'Stationary Head' was an 'Essential' (as per TGM) and is the 'centre of the pivot'. Maybe I'm misinterpreting but I envisioned the phase of the early downswing to be an almost 'rigid' movement. Where the 'arms/club/shoulders' all move as one unit but rotating around the C7 (or Sternum Notch) centre of pivot. Therefore if you used the hands position as a reference point and measured its distance to the 'centre of pivot' , that would provide the radius of the early downswing phase. I have assumed that the hands then move progressively away from the centre of pivot as the swing progresses from P2 -P6 and that the radius (distance from hands to centre of pivot) gets progressively longer (is that correct?). Imho, you cannot just use a face-on view to track the real hub path because it is not 'normal' to the LFFW plane which could be changing its inclination with the ground during the downswing. I did a simple experiment by drawing a circle on a piece of paper and then folding it (through the middle) so that it had a 120 degree angle between the 2 halves and then just placed it on a shelf (so that the top half was flat against a wall) and looked at it from a 'face on view'. It looked like the hand path seen on the Adam Scott video you posted above. The curvature you see from the face-on view is an optical illusion and cannot represent an 'endless belt' from a physics standpoint. IMHO , the 'Law of the Flail' is a better representation of the golf swing. Note: I've asked someone who has a 3D analysis tool to see if he can track the hand/hub path (of a high level golfer) from a 'normal to the LFFW plane' view. This should clear things up for me. You wrote-: " Maybe I'm misinterpreting but I envisioned the phase of the early downswing to be an almost 'rigid' movement. Where the 'arms/club/shoulders' all move as one unit but rotating around the C7 (or Sternum Notch) centre of pivot. Therefore if you used the hands position as a reference point and measured its distance to the 'centre of pivot' , that would provide the radius of the early downswing phase." I don't think of the hands moving around the center of the pivot (which you believe is C7). I only think of the left arm as a lever of fixed length and the hands (actually left hand) as simply being the peripheral end of the lever. The lever can move due to the pivot motion, which moves the left shoulder socket and the lever during the early downswing and where there is very little rotation of the left arm around the fulcrum point of the left shoulder socket prior to the release of PA#4 (between P4 and P5). Then the lever (left arm) moves mainly due to rotation of the left arm around the fulcrum point of the left shoulder socket after the release of PA#4 (which accounts for its more circular motion between P5 and P5.5). I never think of any rotary motion of the left arm (and therefore the left hand) happening relative to the fulcrum point of C7. You also believe that the straight line appearance of the hand arc path between P4 and P5 is an optical illusion due to the fact that the hand arc path is tilted back relative to a face-on camera lens. I think that your "belief" has zero merit. Consider Jamie Sadlowski's hand arc path from face-on. Note that the hand arc path looks relatively straight between point 1 and point 2 (which represents the P4 => P5 time period), while it is very curved between point 2 and point 3 (which represents the P5 => P5.5 time period). You would presumably claim that the relatively "straight line" section between point 1 and point 2 is an optical illusion due to the hand arc path being tilted back relative to the camera lens. I would reject that type of argument for the following reasons. Consider Jamie Sadlowski's hand arc path from a DTL view. Image 1 is at P4, image 2 is at P5 and image 3 is at P5.5. Note that the hand arc path is tilted back less (measuring 67 degrees between P4 and P5) than between P5 and P5.5 (where it is tilted back far more than 33 degrees). Therefore, there should be less camera angle distortion affecting the P4 => P5 section of the hand arc path than the P5 => P5.5 section of the hand arc path, and yet the "reality" is that the hand arc path is much more straight between P4 and P5 than between P5 and P5.5. Secondly, consider David Toms' hand arc path. Note that his whole hand arc path is very circular in shape (with an uniformly large imaginary radius) and that there is no long "straight line" section between P4 and P5. Here is a DTL view of his hand arc path. Image 1 is at P4 and image 2 is at P5. Note that the hand arc path is less steep than Jamie Sadlowski's hand arc path and it measures 63 degrees (which means that it is tilted back 37 degrees). Theoretically, according to your "optical illusion" theory, that should cause the hand arc path to appear "straight" between P4 and P5, but it actually looks circular in his face-on view image. So, that "fact" seemingly disproves your "optical illusion" theory. I believe that Jamie Sadlowski's hand arc path is far less circular than David Toms' hand arc path between P4 and P5 and I believe that it is a "real fact", and I don't believe that it is an optical illusion. Jeff.
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Post by dubiousgolfer on Mar 1, 2017 19:48:59 GMT -5
Dear Dr Mann It certainly looks like you are correct from having read some of the conclusions from this article by Steven M Nesbit and Ryan McGinnis. jssm.org/vol8/n2/11/v8n2-11pdf.pdfI couldn't understand all of it but the conclusions have shocked me because they prove that I have not understood or been misguided by golf instruction where they have said the centre of the swing is the sternum notch. The document states that the hub path has "a constantly moving center-of-curvature during the downswing" . So my simplified perception of the golf swing has been incorrect all these years. The 'swing model' in my head of the arms being attached to a rigid bar (that connects the shoulder joints) with a central pivot point (the sternum notch) is wrong. Key Points From PDF below: • The golf swing hub path was found to have a complex geometry with significantly changing radii, and a constantly moving center-of-curvature during the downswing. • The hub path differed considerably among subjects, however a three phase radius-based pattern was revealed that aligned with distinct stages of the downswing. • The shape and purpose of the hub path geometry appears to result from a complex combination of achieving equilibrium between the golfer and the club, and a purposeful configuring of the path to control the outward movement of the club while minimizing the kinetic loading on the golfer yet transferring the maximum kinetic quantities to the club.
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Post by imperfectgolfer on Mar 2, 2017 23:03:49 GMT -5
Dear Dr Mann It certainly looks like you are correct from having read some of the conclusions from this article by Steven M Nesbit and Ryan McGinnis. jssm.org/vol8/n2/11/v8n2-11pdf.pdfI couldn't understand all of it but the conclusions have shocked me because they prove that I have not understood or been misguided by golf instruction where they have said the centre of the swing is the sternum notch. The document states that the hub path has "a constantly moving center-of-curvature during the downswing" . So my simplified perception of the golf swing has been incorrect all these years. The 'swing model' in my head of the arms being attached to a rigid bar (that connects the shoulder joints) with a central pivot point (the sternum notch) is wrong. Key Points From PDF below: • The golf swing hub path was found to have a complex geometry with significantly changing radii, and a constantly moving center-of-curvature during the downswing. • The hub path differed considerably among subjects, however a three phase radius-based pattern was revealed that aligned with distinct stages of the downswing. • The shape and purpose of the hub path geometry appears to result from a complex combination of achieving equilibrium between the golfer and the club, and a purposeful configuring of the path to control the outward movement of the club while minimizing the kinetic loading on the golfer yet transferring the maximum kinetic quantities to the club. I am familiar with that Nesbit paper, and the "fact" that the hub path has a varying radius at different time points during the downswing. Your previous "belief" that the center of the swing is near the sternal notch makes no sense to me. The reality is that in a TGM swinger, the fulcrum of the left arm swinging motion is the left shoulder socket, but it doesn't remain stationary throughout the downswing. Also, golfers vary in the timing and speed of release of PA#4 (left arm) and they also vary in the planar shifts that happen to the left arm/hand during the downswing, so it is not surprising that the hand arc path of different PGA tour golfers vary a lot. I have repeatedly stated that the most useful concept when it comes to predicting the timing and speed of release of PA#2 is that it is mainly affected by the change in the circular radius of the hand arc path per unit time, and that a golfer can vary the amount of club-releasing power by varying the shape of the hand arc path (which is the principle underlying the aiming point technique). However, I have never discovered any golf instructor, or golf theorist, who can precisely state how best to vary the complex underlying biomechanical factors that determine the shape of the hand arc path - in order to create an optimum club-release action. Bryson DeChambeau has potentially made his personal hand arc path pattern more consistent by i) keeping his head stationary during the downswing; ii) by always having the standard amount of secondary axis tilt and by avoiding varying amounts of left lateral bend that can significantly influence the path of motion of his left shoulder socket; and iii) by having a zero-plane shift golf swing action. Jeff.
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Post by dubiousgolfer on Mar 3, 2017 19:16:07 GMT -5
Many thanks for the reply. My belief about the sternum notch being centre of swing probably came from an old book of mine called 'Play Better Golf ' by Beverly Lewis (page 26) and also videos like the one below from Shawn Clement. www.youtube.com/watch?v=G0BRc8f56AcBoth book (about the top of the spine being the centre of the swing circle) and Clement's videos matched up and it got wrongly 'stuck' in my way of thinking.
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Post by tgminstructor on Apr 17, 2017 16:11:54 GMT -5
The Endless Belt (2-K) is in chapter 2, Statement of Principle. Homer is talking about the principle; linear speed vs. angular speed. The further back your aiming point is the larger the pulley and more sweep release. The further forward your aiming point the smaller the pulley and the more snap release. Also the further forward your aiming point the longer the line (straight line effort to get there).
The aiming point is more utilized by hitters because of their straight line thrust. Swingers use the conservation of angular momentum in place of the aiming point.
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Post by imperfectgolfer on Apr 17, 2017 16:21:11 GMT -5
The Endless Belt (2-K) is in chapter 2, Statement of Principle. Homer is talking about the principle; linear speed vs. angular speed. The further back your aiming point is the larger the pulley and more sweep release. The further forward your aiming point the smaller the pulley and the more snap release. Also the further forward your aiming point the longer the line (straight line effort to get there). The aiming point is more utilized by hitters because of their straight line thrust. Swingers use the conservation of angular momentum in place of the aiming point. I think that Homer Kelley got his endless belt orientation wrong - because the straight line section in "real life" pro golfers is not oriented from right-to-left with the imaginary pulley situated close to impact (as shown in his book). Here is Jamie Sadlowski's hand arc path. Note that the straight line section of his hand arc path is between point 1 and point 2, and it is oriented away from the target. The pulley section is situated in the mid-downswing - between point 2 and point 3 - and that causes a random PA#2 release action. I also think that the COAM principle does not apply to TGM swingers because the TGM swinging action can be better likened to a driven double swing model and not a simple double pendulum swing model. Simple double pendulum swing model Note that the central arm slows down when the peripheral arm releases. Driven double pendulum swing model Note that the central arm does not slow down when the peripheral arm releases. Jeff.
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Post by dubiousgolfer on Apr 24, 2017 7:43:12 GMT -5
Dr Mann
So can I assume that the 'Aiming point' is a projection of the 'straight part' of the 'endless belt' (orientated as per your Sadlowski description) to a point on the ground?
I don't understand any distinction between 'Hitter' and 'Swinger' with regards 'Conservation of angular momentum'. It is a universal law in Physics so will always be applicable in the golf swing if there is any element of rotational motion of a mass happening.
The strange thing about 'double pendulums' and 'driven double pendulums' are that its very difficult to predict the motion (see You Tube video below).
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Post by imperfectgolfer on Apr 25, 2017 0:26:32 GMT -5
Dr Mann So can I assume that the 'Aiming point' is a projection of the 'straight part' of the 'endless belt' (orientated as per your Sadlowski description) to a point on the ground? I don't understand any distinction between 'Hitter' and 'Swinger' with regards 'Conservation of angular momentum'. It is a universal law in Physics so will always be applicable in the golf swing if there is any element of rotational motion of a mass happening. The strange thing about 'double pendulums' and 'driven double pendulums' are that its very difficult to predict the motion (see You Tube video below). Yes - the aiming point on the ground is where the straight line section of the hand arc path is directed. I think that the principle of COAM does not apply to the physics of the double pendulum motion of the golf downswing because COAM is based on a "fixed" amount of energy that is inputted into the system, while in a "real life" golf swing a golfer can input further energy into the downswing action during the double pendular motion that will prevent the left arm from slowing down as the club releases. The physics of the chaotic double pendular motion has no relevance to a golf swing because it describes the behaviour of the COAM-based system after P7 - where the pendulum swing back-and-forth in a chaotic manner. Jeff.
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Post by dubiousgolfer on Apr 25, 2017 7:41:25 GMT -5
Again, many thanks.
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Post by dubiousgolfer on May 23, 2017 5:54:48 GMT -5
Dr Mann I was just looking at your diagram of Tiger Woods and the trace of his shoulder path. Isn't the shoulder path a type of endless belt ? Is there a relationship between the endless belt shape of the shoulder path and the endless belt of the hand hub path?
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Post by imperfectgolfer on May 23, 2017 9:08:54 GMT -5
Dr Mann I was just looking at your diagram of Tiger Woods and the trace of his shoulder path. Isn't the shoulder path a type of endless belt ? Is there a relationship between the endless belt shape of the shoulder path and the endless belt of the hand hub path? Yes - there is a strong causal connection between the motion of the left shoulder socket and the hand arc path. Between P4 and P5 (prior to the release of PA#4), the left shoulder socket moves mainly horizontally, but slightly downwards, towards the target as the upper torso roates around the rotational axis of the upper thoracic spine. During that time period, the hands will move mainly backwards (away from the target) and slightly downwards as the hands move from the 11 o'clock position (presuming that's their P4 position) to the 10 o'clock position and the hand arc path is not yet very circular in shape. Then, PA#4 starts to release between P5 and P5.5 and that causes the hand arc path to become more circular - but not perfectly circular because the left shoulder socket is still moving horizontally towards the target during the P5 to P5.5 time period, which causes the hand arc path to be variably elliptical in shape. The circular shape of the hand arc path then induces the release of PA#2 starting near P5.5 in golfers who have a random club release pattern - depending on how "tightly" circular the hand arc path is at any point in time during the mid-downswing. Then, starting at P5.5, the left shoulder socket moves mainly upwards (with no more horizontal travel), and that causes the hand arc path to also move upwards thereby shortening the hand arc path radius between P5.5 and impact and potentially inducing parametric acceleration of the club, which can make the club release slightly faster. That's why I disagree with Mandrin's claim that motion at the level of the left shoulder socket has no effect on the club release phenomenon. I think that the shape of the hand arc path is due to two interacting biomechanical factors - i) the 3-D motion of the left shoulder socket in space and ii) left arm rotation around the fulcrum point of the left shoulder socket - and the interaction is very complex and variable from golfer-to-golfer. Jeff.
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