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Post by dubiousgolfer on Jun 19, 2020 6:47:01 GMT -5
Dr Mann
I'm finding that the forces that can be applied by each hand can theoretically have a 'double' effect .
For example (a possible theoretical scenario):
1. A right hand linear push force across the shaft below the coupling point (ie. a down and outwards push directed away from target) will cause an MOF that will tend to be negative (ie. assist lag).
but also
2. That same push force in point 1 could assist a 'positive' hand couple when combined with any pull force by the left hand (above the coupling point) across the shaft (down and targetwards).
Further , any linear force applied by the left hand across the shaft (down and targetwards above coupling point) would create a positive MOF, but additionally , with the assistance of the right hand force in point 2 , add a positive hand couple to an already positive MOF.
It's definitely going to be 'challenging' to describe the biomechanics by theorising the 'combined cause and effect' of the 'hand couple' and 'MOF' influences by each hand?
DG
Addendum : Apologies - got this wrong again (so struck through).
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Post by imperfectgolfer on Jun 19, 2020 7:43:01 GMT -5
DG,
You wrote-: "1. A right hand linear push force across the shaft below the coupling point (ie. a down and outwards push directed away from target) will cause an MOF that will tend to be negative (ie. assist lag)."
I don't understand how that is possible! How can a push-force across-the-shaft below the coupling point with the right hand increase lag.
Jeff.
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Post by dubiousgolfer on Jun 19, 2020 7:50:21 GMT -5
Here is Dr Kwon's image of the hands and also Koike graphs below. I have drawn the x-y coordinate system as if the z axis is pointing out of the screen, then included the general force directions (in green and black) of the right and left hand to reflect the koike graphs. How could one theorise the biomechanics to produce those general force directions? Right Hand -positive x-axis force 1. Could it be caused by the protraction of the right scapula ,downplane movement of the right shoulder socket, right lateral flexion, push force by attempted extension of right elbow. Some combination of which is 'transmitting' a force through the folded right arm and dorsiflexed wrist? Right hand - negative y-axis force (in shaft direction towards hosel) 2. Passive right arm adduction with pitch elbow which causes the forearm/hand to move clockwise into the shaft (from the golfers own eyesight perspective). Left arm - negative x-axis force 1. Targetwards motion of left shoulder socket Left arm - positive y-axis force 2. Active left shoulder girdle to pull arm down and out. 3. Downwards movement of upper torso (ie. Sam Snead squat?) caused by activation of the iliopsoas . I'm looking forward to Dr Mann's theories on the biomechanics involved. DG
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Post by dubiousgolfer on Jun 19, 2020 7:56:36 GMT -5
DG, You wrote-: " 1. A right hand linear push force across the shaft below the coupling point (ie. a down and outwards push directed away from target) will cause an MOF that will tend to be negative (ie. assist lag)." I don't understand how that is possible! How can a push-force across-the-shaft below the coupling point with the right hand increase lag. Jeff. Dr Mann It's the same physics for the MOF that is caused by the 'Net Force'. That 'Net Force' doesn't need to go through the coupling point (although they are using it as a reference point for their inverse dynamics approach). As long as the force is not going through the COM of the club it will cause an MOF. For example , I could apply a force across the shaft one inch below the COM (ie. more towards the grip end than the hosel end) and that will cause a MOF . DG
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Post by imperfectgolfer on Jun 19, 2020 8:13:09 GMT -5
DG, You wrote-: " 1. A right hand linear push force across the shaft below the coupling point (ie. a down and outwards push directed away from target) will cause an MOF that will tend to be negative (ie. assist lag)." I don't understand how that is possible! How can a push-force across-the-shaft below the coupling point with the right hand increase lag. Jeff. Dr Mann It's the same physics for the MOF that is caused by the 'Net Force'. That 'Net Force' doesn't need to go through the coupling point (although they are using it as a reference point for their inverse dynamics approach). As long as the force is not going through the COM of the club it will cause an MOF. For example , I could apply a force across the shaft one inch below the COM (ie. more towards the grip end than the hosel end) and that will cause a MOF . DG I disagree! The MOF is produced by a linear net force pulling the club at an angle to a "force-along-the-shaft" direction and not a force pushing the club in a "force-across-the-shaft" direction. Jeff.
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Post by dubiousgolfer on Jun 19, 2020 8:31:52 GMT -5
Dr Mann Look at my diagram below from one of the frames of SMK's 'Intro Kinetics' video. I've added a force closer to the COM of the club . Even if those forces were vertical (ie. 90 degrees and across the shaft) one would still create an MOF in the direction of the blue arrows. It doesn't matter if its a push or a pull. DG
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Post by imperfectgolfer on Jun 19, 2020 15:45:28 GMT -5
In your diagram, the force is directed downwards-and-outwards. That will create a MoF that will cause the club to rotate clockwise - as shown in Kwon's diagram below. In my mental picture of a right hand couple producing a "force-across-the-shaft", that force is working upwards (anti-clockwise) in order to counter any tendency of the MoF to produce a clockwise rotation of the shaft that will increase lag. Jeff.
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Post by imperfectgolfer on Jun 19, 2020 19:27:35 GMT -5
Here is Dr Kwon's image of the hands and also Koike graphs below. I have drawn the x-y coordinate system as if the z axis is pointing out of the screen, then included the general force directions (in green and black) of the right and left hand to reflect the koike graphs. How could one theorise the biomechanics to produce those general force directions? Right Hand -positive x-axis force 1. Could it be caused by the protraction of the right scapula ,downplane movement of the right shoulder socket, right lateral flexion, push force by attempted extension of right elbow. Some combination of which is 'transmitting' a force through the folded right arm and dorsiflexed wrist? Right hand - negative y-axis force (in shaft direction towards hosel) 2. Passive right arm adduction with pitch elbow which causes the forearm/hand to move clockwise into the shaft (from the golfers own eyesight perspective). Left arm - negative x-axis force 1. Targetwards motion of left shoulder socket Left arm - positive y-axis force 2. Active left shoulder girdle to pull arm down and out. 3. Downwards movement of upper torso (ie. Sam Snead squat?) caused by activation of the iliopsoas . I'm looking forward to Dr Mann's theories on the biomechanics involved. DG DG, You asked-: " Right Hand -positive x-axis force 1. Could it be caused by the protraction of the right scapula ,downplane movement of the right shoulder socket, right lateral flexion, push force by attempted extension of right elbow. Some combination of which is 'transmitting' a force through the folded right arm and dorsiflexed wrist?" A tendency to straighten the right wrist or right elbow could cause the right hand to produce a positive "force-across-the-shaft". More distant biomechanical events (eg. downplane motion of the right shoulder socket, right scapular protraction) may cause the right hand to produce a positive "force-across-the-shaft" and/or a positive "force-down-the-shaft" in the direction of the butt end of the club. I doubt that right arm adduction will produce a negative "force-down-the-shaft" phenomenon even if the golfer uses a pitch elbow motion, and I think that it will more likely produce a positive "force-across-the-shaft" and/or a positive "force-down-the-shaft".
I think that it is a waste of mental effort trying to imagine whether an increased spine bend inclination angle due to contraction of the iliopsoas muscles will affect the force exerted by the left hand on the club handle that is independent of the release of PA#4.
Jeff.
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Post by dubiousgolfer on Jun 19, 2020 19:50:14 GMT -5
In your diagram, the force is directed downwards-and-outwards. That will create a MoF that will cause the club to rotate clockwise - as shown in Kwon's diagram below. In my mental picture of a right hand couple producing a "force-across-the-shaft", that force is working upwards (anti-clockwise) in order to counter any tendency of the MoF to produce a clockwise rotation of the shaft that will increase lag. Jeff. Yes, you are correct - I struck through my previous post - apologies. DG
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Post by dubiousgolfer on Jun 19, 2020 19:57:36 GMT -5
Dr Mann
That negative force 'down the shaft' by the trail hand just doesn't seem possible unless the right hand is not travelling downplane as quick as the left hand.
DG
PS. Might that negative force be 'non-optimal' considering that Sasho MacKenzie stipulates that 'linear' work accounts for 90% of the predictability of increase in clubhead speed? In which case wouldn't it be beneficial for the right hand to have as much positive force 'up the shaft' (towards the butt end).
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Post by imperfectgolfer on Jun 20, 2020 12:42:19 GMT -5
Dr Mann That negative force 'down the shaft' by the trail hand just doesn't seem possible unless the right hand is not travelling downplane as quick as the left hand. DG PS. Might that negative force be 'non-optimal' considering that Sasho MacKenzie stipulates that 'linear' work accounts for 90% of the predictability of increase in clubhead speed? In which case wouldn't it be beneficial for the right hand to have as much positive force 'up the shaft' (towards the butt end). Under those circumstances, where the left hand is pulling the club handle downplane while the right hand is not quite keeping up, it could produce a negative "force-up-the-shaft" scenario. How much the right arm adduction maneuver potentially plays a role in increasing the speed of release of PA#4 is unknown. Jeff.
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Post by dubiousgolfer on Jun 26, 2020 19:14:36 GMT -5
I have been looking at the Koike graphs compared to this other grip force article and this complicates the hand forces even further. repository.lboro.ac.uk/articles/Measurement_and_analysis_of_grip_force_during_a_golf_shot/9567140If you look at the graphs and images for the scratch golfer swing below , the graphs seem to make more sense 'intuitively' than Koike's. Koike's graphs were measuring the components of the force on the grip in the 'x' axis direction in the plane of the swing but the left/right hand forces look very symmetrical throughout the downswing, probably because of a split hand grip . The below graph shows a peak in left hand force during transition , a trough around P5 , a similar peak rising during release to P6, decreasing into impact. The right hand force seems to be appreciably smaller than the left hand force but fairly constant in the early downswing but then starts to peak during release to P6 and then decreasing into impact. DG PS. When I mention 'intuitively' , I meant that it seems like a pivot release of PA#4 during transition (left arm swinging action) and not much force being attributed by the right arm compared to the left.
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Post by dubiousgolfer on Jun 27, 2020 8:57:51 GMT -5
On reflection , I think I can understand why Koike's left hand force graph 'a' doesn't match the other article's left hand graph. The latter is the total force being applied to the grip in the x,y,z directions , therefore the troughs and even some of the peaks could be attributed to forces in the y,z direction (the same reasoning has to apply to the right hand too).
Basically , it's futile to compare the graphs.
DG
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Post by dubiousgolfer on Jul 3, 2020 7:18:39 GMT -5
Dr Mann
Regarding your new thoughts about the golf swing, will the term 'Release' need to be redefined (or should it even exist)?
I can understand the 'Release of the PA's in TGM terms but if they are deemed insufficient to explain the kinetics of the golf swing, should there even be a term called 'Release' because it seems so nebulous?
One new golf instruction person on the 'Hackers Paradise' forum (that I am registered on) defines release as the following:
--------------------------------------------------- A Release is when you “release” all your angles or your wrists, arms, left leg, and middle torso go from flexion to extension.
Different players depending, on speed, need different release patterns to create height and spin. Those release patterns are based on speed and the face angle they have at P6. If the face is open, the only way to square it up is release it early or throw your body over the top. Let’s say you’re Bryson, he can come from P6 with his face shut down and hold off his release until his hands are past his left shoe. That creates a low launching shot with plenty of spin Let’s say you’re younger, like some of our high level juniors. To get height and spin, we need them to release early, and as they mature and get speed they can have more of a shut face and release later which creates a ton of spin and height.
My reference to other instructors being dogmatic (teaching only ONE release) was in reference to a couple Instructors in particular who say that you must stall your body and release your hands. That’s PoppyCock and That’s what I would call early and not efficient. This reduces speed and causes all sorts of issues with consistency. While they may be able to execute it really well and teach a few with success, it’s not for everyone and poor coaching and selling Snake Oil. I feel bad for them because they just don’t know better. I also feel bad for people who pay for their Services.
My point is that, and we say this all the time, “it depends” and that’s why we have varying tolerances to allow different ways to do the same motion pattern. The release is just something that has a range of options depending on golfers’ abilities. -----------------------------------------------------
DG
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Post by imperfectgolfer on Jul 3, 2020 13:28:53 GMT -5
I prefer to think of the release in TGM terms - release of PA#4, PA#2 and PA#3 - and also in terms of a DH versus non-DH hand release action through impact.
Jeff.
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