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Post by imperfectgolfer on Sept 10, 2019 11:22:59 GMT -5
See this BeBetterGolf video featuring Baden Schaff's opinions on body rotation.
Note the many comments made by uninformed golfers.
What do you think regarding Baden Schaff's opinion that it is better to continue to rotate the body post-impact compared to golfers who seem to stall their body rotation at impact?
Jeff.
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Post by dubiousgolfer on Sept 10, 2019 19:05:17 GMT -5
Dr Mann
Doesn't the amount of post-impact body rotation depend upon the arm-release action preferred?
If a golfer prefers a CP arm release , won't he rotate more through impact compared to a golfer who prefers a CF arm release action?
DG
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Post by imperfectgolfer on Sept 10, 2019 22:41:35 GMT -5
Dr Mann Doesn't the amount of post-impact body rotation depend upon the arm-release action preferred? If a golfer prefers a CP arm release , won't he rotate more through impact compared to a golfer who prefers a CF arm release action? DG Yes. If a golfer wants to use the combination of a CP-arm release action + no-roll hand release action between impact and P7.4, then it is very advantageous to continue to rotate the body more open during the followthrough time period. However, if a golfer decides to use a CF-arm release action combined with a delayed full-roll hand release action through impact, then he he does not necessarily need to continue to actively rotate the body (pelvis and upper torso) between impact and P7.4+. Rory McIlroy uses that biomechanical combination for his driver swing - as seen in the capture images below. Note that Rory gets his pelvis open by P6 (image 4), but he does not continue to rotate his pelvis more open between P6 and P8 (image 6). However, his upper torso continues to rotate very actively through impact. I think that Baden Schaff's opinions on this issue are over-simplistic, and too narrow-minded. He also wrongly claims that Rory has a "hanging back" problem regarding his upper torso - but I can see no evidence of that in his swing videos.
Jeff.
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Post by dubiousgolfer on Sept 11, 2019 9:27:10 GMT -5
Dr Mann
Many thanks for the above
I've read that there is also an argument that golfers might stall or rotate through impact depending on their preference to release their postural angles to avoid muscular or structural stress. That whatever their preference , its a means to decelerate and absorb the energy in the follow-through. Is this a valid opinion?
DG
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Post by imperfectgolfer on Sept 11, 2019 13:17:01 GMT -5
Dr Mann Many thanks for the above I've read that there is also an argument that golfers might stall or rotate through impact depending on their preference to release their postural angles to avoid muscular or structural stress. That whatever their preference , its a means to decelerate and absorb the energy in the follow-through. Is this a valid opinion? DG I would have to study the reasoning behind any "belief" - that a golfer stalls the body rotation at impact in order to reduce muscular/structural stress on the body - in order to determine whether the reasoning could be valid. My personal opinion is that stalling will increase stress on the body's structural components. How does body deceleration (via the process of stalling-through-impact) absorb energy? Jeff.
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Post by dubiousgolfer on Sept 11, 2019 18:03:48 GMT -5
Couldn't this be explained by physics? I haven't got a hand path image of Rory or Wolf but I can easily imagine that their hands 'turn the corner' more acutely than Bryson with a later release of PA2#. The hands are moving in one direction while the clubs COM moving in another which causes an increase in the shaft tension (probably greater than the tension caused by Bryson's hand path). The shaft tension pulls on the lead arm slowing it down while also pulling on the COM of the club (ie. centripetal acceleration). Therefore isn't there some energy being redistributed from the body rotation via the arms to the club but being done more efficiently by Wolf and Rory (which might explain why their body/arms decelerate more than Bryson)? DG PS. The above is mentioned by Rod White on Tutelmans website. --------------------------- How is the energy transferred? We have discussed the golf swing in terms of the conservation of energy and momentum, and showed that the energy is transferred to the club as the swing unfolds, but what actually happens – where are the forces that make this happen? The figure shows a ‘stroboscopic’ view of the golf swing. Have a close look at the direction of the clubhead midway through the swing – this is indicated approximately by the red arrow. Now look where the hands move at the same time – the blue arrow: in a different direction! Obviously the hands and clubhead cannot continue to move in different directions, they are restrained by the fixed length of the shaft. The diverging directions of the club and hands results in a large tension in the shaft. The tension pulls against the club head causing it to accelerate, and pulls against the hands causing them to decelerate. It is the differing directions of the hands and club that are ultimately responsible for the energy transfer. ----------------------------------------------
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Post by imperfectgolfer on Sept 11, 2019 23:48:33 GMT -5
Couldn't this be explained by physics? I haven't got a hand path image of Rory or Wolf but I can easily imagine that their hands 'turn the corner' more acutely than Bryson with a later release of PA2#. The hands are moving in one direction while the clubs COM moving in another which causes an increase in the shaft tension (probably greater than the tension caused by Bryson's hand path). The shaft tension pulls on the lead arm slowing it down while also pulling on the COM of the club (ie. centripetal acceleration). Therefore isn't there some energy being redistributed from the body rotation via the arms to the club but being done more efficiently by Wolf and Rory (which might explain why their body/arms decelerate more than Bryson)? DG PS. The above is mentioned by Rod White on Tutelmans website. --------------------------- How is the energy transferred? We have discussed the golf swing in terms of the conservation of energy and momentum, and showed that the energy is transferred to the club as the swing unfolds, but what actually happens – where are the forces that make this happen? The figure shows a ‘stroboscopic’ view of the golf swing. Have a close look at the direction of the clubhead midway through the swing – this is indicated approximately by the red arrow. Now look where the hands move at the same time – the blue arrow: in a different direction! Obviously the hands and clubhead cannot continue to move in different directions, they are restrained by the fixed length of the shaft. The diverging directions of the club and hands results in a large tension in the shaft. The tension pulls against the club head causing it to accelerate, and pulls against the hands causing them to decelerate. It is the differing directions of the hands and club that are ultimately responsible for the energy transfer. ---------------------------------------------- According to the COAM principle, some energy is transferred to the club during the release of PA#2 and that causes the left arm to slow down slightly. However, the degree of left arm slowing is small in a good kinematic sequence eg. hands reach their peak speed of 22mph at P5.5 and then slow down to 19mph by impact. However, they are still moving forward at 19mph which should allow a golfer to efficiently perform a DH-hand release action. Also, any small degree of slowing of the left arm in the later downswing should not produce any stalling of body rotation. Also, where is any "evidence" that Rory's hands slow down more than Bryson's hands during the later downswing as a result of the release of PA#2? Also, why should it cause stalling of any body rotation? Jeff.
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Post by syllogist on Sept 12, 2019 10:11:07 GMT -5
Very interesting topic. COAM would apply if it were not for external torques in the rotational system. I personally disregard double pendulum models. I look at the release phase of the swing as rotation within the rotational system. An easy way to explain this is to consider the grip held in along the roots of the trail hand fingers. During the downswing, from the transitional phase to the release point, the roots of the fingers are angled to describe the desired inclination of the swing plane. The fastest and most efficient means of release is when during release, the angle of the roots of the fingers are made to change from pointed along the downswing plane to pointing along the follow through plane. This is what I would call rotation within the rotational system, or "second order" rotation. All else being equal, the greater and the faster second order rotation there is, the greater the hand deceleration. In fact, all "release types" can be distinguished by the degree of second order rotation. Anyway, this is my theory.
Syllogist
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Post by dubiousgolfer on Sept 12, 2019 11:26:07 GMT -5
Couldn't this be explained by physics? I haven't got a hand path image of Rory or Wolf but I can easily imagine that their hands 'turn the corner' more acutely than Bryson with a later release of PA2#. The hands are moving in one direction while the clubs COM moving in another which causes an increase in the shaft tension (probably greater than the tension caused by Bryson's hand path). The shaft tension pulls on the lead arm slowing it down while also pulling on the COM of the club (ie. centripetal acceleration). Therefore isn't there some energy being redistributed from the body rotation via the arms to the club but being done more efficiently by Wolf and Rory (which might explain why their body/arms decelerate more than Bryson)? DG PS. The above is mentioned by Rod White on Tutelmans website. --------------------------- How is the energy transferred? We have discussed the golf swing in terms of the conservation of energy and momentum, and showed that the energy is transferred to the club as the swing unfolds, but what actually happens – where are the forces that make this happen? The figure shows a ‘stroboscopic’ view of the golf swing. Have a close look at the direction of the clubhead midway through the swing – this is indicated approximately by the red arrow. Now look where the hands move at the same time – the blue arrow: in a different direction! Obviously the hands and clubhead cannot continue to move in different directions, they are restrained by the fixed length of the shaft. The diverging directions of the club and hands results in a large tension in the shaft. The tension pulls against the club head causing it to accelerate, and pulls against the hands causing them to decelerate. It is the differing directions of the hands and club that are ultimately responsible for the energy transfer. ---------------------------------------------- According to the COAM principle, some energy is transferred to the club during the release of PA#2 and that causes the left arm to slow down slightly. However, the degree of left arm slowing is small in a good kinematic sequence eg. hands reach their peak speed of 22mph at P5.5 and then slow down to 19mph by impact. However, they are still moving forward at 19mph which should allow a golfer to efficiently perform a DH-hand release action. Also, any small degree of slowing of the left arm in the later downswing should not produce any stalling of body rotation. Also, where is any "evidence" that Rory's hands slow down more than Bryson's hands during the later downswing as a result of the release of PA#2? Also, why should it cause stalling of any body rotation? Jeff. Dr Mann I've looked at the 3 Lever model of the golf swing and drawn some forces but obviously this is just hypothetical and probably bears no relation to what may be happening in a real golfers swing. If my force diagram is accurate , then body rotation might slow down as per my diagram below (unsure as I'm not an expert in free body force diagrams). I don't know whether there would be any major slowing down in upper body pivot rotation caused by these increased 'tension' forces in the lead arm. Further , I doubt whether any slight differences in the timing of the release of PA2# would explain the differences in body rotation seen between Bryson and Rory. DG
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Post by imperfectgolfer on Sept 12, 2019 23:12:11 GMT -5
According to the COAM principle, some energy is transferred to the club during the release of PA#2 and that causes the left arm to slow down slightly. However, the degree of left arm slowing is small in a good kinematic sequence eg. hands reach their peak speed of 22mph at P5.5 and then slow down to 19mph by impact. However, they are still moving forward at 19mph which should allow a golfer to efficiently perform a DH-hand release action. Also, any small degree of slowing of the left arm in the later downswing should not produce any stalling of body rotation. Also, where is any "evidence" that Rory's hands slow down more than Bryson's hands during the later downswing as a result of the release of PA#2? Also, why should it cause stalling of any body rotation? Jeff. Dr Mann I've looked at the 3 Lever model of the golf swing and drawn some forces but obviously this is just hypothetical and probably bears no relation to what may be happening in a real golfers swing. If my force diagram is accurate , then body rotation might slow down as per my diagram below (unsure as I'm not an expert in free body force diagrams). I don't know whether there would be any major slowing down in upper body pivot rotation caused by these increased 'tension' forces in the lead arm. Further , I doubt whether any slight differences in the timing of the release of PA2# would explain the differences in body rotation seen between Bryson and Rory. DG DG, I don't understand the logic of your explanatory reasoning. I cannot understand why you postulate that the body should slow down just because the left arm is being pulled forward via its attachment to the body at the left shoulder socket. Jeff.
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Post by dubiousgolfer on Sept 13, 2019 6:18:51 GMT -5
Dr Mann Its similar to the effects seen in a compound pendulum where energy is transferred from the proximal to distal end. The only way to decelerate each segment is via forces in each 'connection' between masses (increased tension caused by the divergence in movement of the connected segments). The kinematic graph of a compound pendulum is shown to be similar to the graph of a pro tour golfer (according to golfloopy.com) www.golfloopy.com/compound-pendulum/ Individual segment speeds in compound pendulum Tour professional golf swing kinematic sequence DG
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Post by imperfectgolfer on Sept 13, 2019 8:49:05 GMT -5
Dr Mann Its similar to the effects seen in a compound pendulum where energy is transferred from the proximal to distal end. The only way to decelerate each segment is via forces in each 'connection' between masses (increased tension caused by the divergence in movement of the connected segments). The kinematic graph of a compound pendulum is shown to be similar to the graph of a pro tour golfer (according to golfloopy.com) www.golfloopy.com/compound-pendulum/ Individual segment speeds in compound pendulum Tour professional golf swing kinematic sequence DG That compound pendulum is simply powered by gravity and where no extra energy can be inputted into the system. In a golfer's downswing, the golfer can continuously control the amount of energy being generated to keep the pivot action from slowing down by continuously ongoing muscular activity. I cannot understand the value of comparing a golfer's active pivot action to the inner machinations of a passive compound pendular system. Jeff.
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Post by dubiousgolfer on Sept 14, 2019 11:16:08 GMT -5
Dr Mann
Yes , these 'models' are of limited usefulness but was just trying to figure out if there was some physics explanation for the body stalling in Rory and Wolfs swing.
I have a few questions about your 2 statements below
"In a golfer's downswing, the golfer can continuously control the amount of energy being generated to keep the pivot action from slowing down by continuously ongoing muscular activity"
" However, in a golf robot club-testing machine and a pro golfer's driver swing (which both work according to the principle of the double pendulum swing model) swing power is only applied to the central arm (lead arm in a golfer) between P4 and P5.5 and the lead arm slows down during the later downswing."
Are you saying that a pro-golfer only uses an active pivot torque between P4 and P5.5 to help release PA4# but is then using just enough active pivot from P5.5 onwards to facilitate their preferred arm/hand release actions? That any active pivot that a pro-golfer uses from P5.5 onwards is not being used to propel the lead arm or assist in creating clubhead speed?
DG
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Post by imperfectgolfer on Sept 14, 2019 15:21:38 GMT -5
DG,
You asked-: "Are you saying that a pro-golfer only uses an active pivot torque between P4 and P5.5 to help release PA4# but is then using just enough active pivot from P5.5 onwards to facilitate their preferred arm/hand release actions? That any active pivot that a pro-golfer uses from P5.5 onwards is not being used to propel the lead arm or assist in creating clubhead speed?".
Yes. The active pivot action between P4 and P5.5 is used to power the release of PA#4, while any active pivot action between P5.5 and P7.5 is mainly used to optimize conditions for an efficient DH-hand release action.
Jeff.
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Post by dubiousgolfer on Sept 15, 2019 6:26:06 GMT -5
Dr Mann
Here is Justin Thomas swing in slow motion and if you look at post impact right image frame (at 6:01) , it looks like he is a 'Drive Holder'.
But if you look at this vimeo video that Sasho MacKenzie published for Justin Thomas's swing (although its a 7-iron and not a Driver), and look at frame 09:50 one can see the 'Total In Plane Torque' component graph (red line) at about P5.5 is still 'positive' all the way through to impact. That positive torque cannot be caused via any positive couple in the hands because I am assuming the clubshaft will move into forward bend at least by P6.5.
So my question is what is causing that positive couple other than the 'net force' which is shown by the 'Purple' dotted arrow? That force is directed more vertically from P6.5 onwards and its 'tail end' is in front of the clubshaft's COM which (due to physics) can cause a positive torque (and I assume will assist in increasing clubhead speed into impact).
I am assuming that the purple vector force is caused by a pull by the lead arm and is a secondary effect due to an active pivot that rotates the lead shoulder socket 'up and back' from P6.5 - P7.
Is this 'positive' torque just something unique to Justin Thomas (and some other Tour golfers) who seem to be 'jumping up' from P6.5 -P7 and are utilising 'Parametric Acceleration'?
DG
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