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Post by dubiousgolfer on Apr 1, 2020 11:28:17 GMT -5
I've been trying to understand how a rotary motion can cause a linear hand path and I think I've found a video that might help visualise what's happening .
Look at 0:41 - 0:56
This is going to take some imagination but try and visualise the green pivot point as being the right shoulder joint , the blue arm as the right humerus , white pivot point the right elbow joint, the red arm as the right forearm , the whole of the yellow rod as your hand with the yellow pivot point being the wrist joint.
If you look carefully in slow motion , one can see that the 'adduction' of the 'humerus' together with the unbending of the 'elbow' , if well timed, will create a 'straight hand path'.
So I'm hoping this provides a visual explanation why a pitch elbow move in front of the right hip and also a blocked elbow more down the right side of the torso can still cause a straight hand path and help prevent the release of PA#2 .
DG
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Post by utahgolfer on Apr 1, 2020 16:28:39 GMT -5
Hi DG,
What do you mean by a straight hand path? The video looks good to me, but it seems to show a curvilinear path that we would see from p4 to p5.5. Isn't it the changing curvilinear hand path that matters? That the hand arc path is less curved from p4 to p5.5, and then more abruptly curved (due to the upward pivoting left shoulder) which first promotes a delay in the release of PA#2 and then an acceleration of the release of PA#2 at about p6.
UG
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Post by dubiousgolfer on Apr 1, 2020 18:22:04 GMT -5
Hi UG
The video won't represent the P positions ,real angles or lengths of the 'humerus vs forearm' but imho it does 'generally' show how a straight hand path could theoretically occur say between P4-P5.5.
Look at frames 0:49 ,0:50 and 0:51 and imagine the blue arm (right humerus) is orientated more horizontal at P4 while having a bent elbow and an acute angle with the red arm.
Then note that when the blue arm adducts (ie. frames 0:49-0:51) and the elbow straightens (if correctly timed) that 'yellow pivot point and rod' (ie.right wrist joint and hand) will move linearly in a straight line.
But of course in a real swing , there is some movement of that right shoulder socket (ie. green pivot point) and the influence of the left arm movement, therefore the hand path will not be perfectly straight and will be curvilinear from P4 to P5.5 .
I think most golfers have a 'random release' between P5.5 and P6.2 if I'm not mistaken.
But does the right arm straighten (in a real golf swing) by some variable amount as the humerus adducts to create that less curved hand path from P4 - P5.5 ? Still unsure to be honest and I'm probably completely wrong about the geometry I'm seeing in that video.
DG
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Post by dubiousgolfer on Apr 1, 2020 20:11:19 GMT -5
Not sure whether this video is correct or representative of PGA Tour golfers but AMG seems to state that the right arm does straighten (not by much) but they haven't mentioned whether there is increased right arm adduction happening at the same time (or any measurement to assess the degree of adduction vs left arm straightening from P4-P5.5). Would have been nice to see if there was any correlation to a 'less curved' hand path to minimise the risk of early release of PA#2.
Dr Mann mentioned that for JS swing , the ribcage slides under the right scapula from P4-P5 and there doesn't seem to be any right arm straightening (is it the same with DJ's swing?).
Maybe there are 2 biomechanical phase movements in the downswing that assist a less curvilinear hand path from P4-P5.5.
1. Involving the ribcage sliding under the right scapula , while scapular becoming more protracted and depressed from P4-P5 2. Increased right arm adduction and straightening from P5-P5.5
Unfortunately not enough evidence to back it up, so no point pursuing this theory.
DG
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Post by imperfectgolfer on Apr 2, 2020 10:37:56 GMT -5
DG, I think that the pendulum pump video is worthless in explaining how golfers generate a "straightish" hand arc path between P4 and P5.5 because there is no right elbow straightening action happening between P4 and P5.5. Here is Dustin Johnson's hand arc path. Note that there is no right elbow straightening action between P4 and P5.5. To produce a "straightish" hand arc path, where the hands are no closer to the target at P5.5 than they were at P4, one needs to combine a finite amount of right arm adduction + a finite degree of right shoulder downplane motion due to a finite amount of counterclockwise rotation of the upper torso combined with a finite amount of right scapular protraction combined with a finite amount of right lateral bend. From a 3-D perspective, this phenomenon is very complex and not easy to explain using simplistic mechanical models. Jeff.
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Post by dubiousgolfer on Apr 2, 2020 13:13:17 GMT -5
Many thanks Dr Mann - Yes , its probably too complex to figure out with these simplistic models .
DG
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