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Post by imperfectgolfer on Apr 19, 2023 18:23:26 GMT -5
DG, You wrote-: " The angle between the forearm and shaft would have to be measured from a viewpoint that is perpendicular to the instantaneous plane formed by those forearm/shaft lines. " Why are you doing the lead wrist angle measurements from a viewpoint that is perpendicular to the instantaneous plane formed by those forearm/clubshaft lines - rather than the viewpoint being parallel to the swingplane? Consider a golfer who uses a very strong lead hand grip where the back of his lead wrist/hand is continuously parallel to the swingplane between P4 => P7 and where the lead wrist uncocking action happens parallel to the swingplane. Would you not measure the lead wrist angle at P5, P6 and P7 in the same way - where the measurement is always made parallel to the swingplane? Consider a golfer who uses a very weak lead hand grip (like Will Zalatoris). Would you not measure his lead wrist angle at P5 and P6 in the plane of the swingplane if the back of the lead wrist is parallel to the swingplane at P5 and P6? What about impact when the back of the lead wrist is perpendicular to the swingplane? Jeff. Dr Mann I am just interpreting what Phil Cheetham implied in that video because he just mentioned the angle formed between the forearm and shaft viewed perpendicular to the plane formed by the forearm/shaft lines. With regard your example of a very strong lead hand grip where the back of the wrist is moving within the swing plane, the lead wrist angle measurement (as I have interpreted it from that video) would still be the angle formed between the shaft and forearm. And one would be able to see and measure the true angle only from a viewpoint which is perpendicular to the swingplane. The same as above would apply to Will Zalatoris if the back of his lead wrist was within the swingplane at P5 and P6. If the back of his lead wrist was perpendicular to the swing plane at impact and one still used the angle formed between the shaft and forearm as lead wrist measurement, then I can only assume that it's 180 degrees minus the PA3 angle. DG Based on your belief that the lead wrist angle in a golfer, who uses a very strong lead hand grip, is measured in the plane of the functional swingplane - as viewed from a viewpoint that is perpendicular to the swingplane. So, let's consider these images of Milo Lines, who uses a very strong lead hand grip. Image 1 is at impact and image 2 is at P7.4. Do you not agree that his lead forearm is straight-line-aligned with his clubshaft at P7.4 so the lead wrist angle measurement should be 180 degrees. However, all of PC's lead wrist angle graphs show a peak lead wrist angle measurement at impact and a decreasing value post-impact.
What's your explanation?
Jeff.
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Post by dubiousgolfer on Apr 19, 2023 19:52:24 GMT -5
Dr Mann If Milo's shaft and lead forearm were in a perfect straight line at P7.4, I would assume that the lead wrist angle would be 180 degrees. But if you look at his slow-mo driver swing post impact , it looks like he still has a lead wrist angle between lead forearm and shaft. Not all of the PC's graphs show a sharp peak before decreasing because some have a small plateau area which I assume would be from P7-P7.1 or P7.2 . I think any sharp decrease in lead wrist angle might be caused by radial deviation post impact into the follow-through. Phil Mickelson's lead wrist angle seems to reach about 170 degrees at impact similar to the image below and then decreases rapidly. We know he has a roller subtype Non-DH hand release action as per below Gif, so maybe it also involves increasing radial deviation immediately post impact. DG
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Post by dubiousgolfer on Apr 19, 2023 20:50:37 GMT -5
Dr Mann
I've listened to some of that SMK podcast and the interesting part was around -1:06:25 to -1:01:00 regarding a study by Chu on 308 amateur golfers. Apparently the wrist hinge angle (ie. angle between lead arm and shaft) at 40 msecs before impact (P6) showed the best association with clubhead speed than any other variable they measured at all the different points in the golf swings. The average wrist hinge angle was 145 degrees at p6 which gave a 140 mph ball speed and for every 10 degrees less angle between shaft and arm (ie. more lag), the ball speed would increase by 5mph.
At -26:26 to -22:40 SMK says in the Chu study there was a wide range of wrist angles at P6 and ball speeds, but if you did that study on PGA pros (SMK has a database of 130) , you don't see much correlation. Just listening now to the question at -24:11 to -13:00 regarding how hand speed contributes to clubhead speed.
Apparently hand speed should peak halfway between shaft vertical and shaft parallel on the downswing about 60 degrees from parallel. But increasing the peak hand speed might not necessarily have a correlation with clubhead speed (some paradox regarding Newtons 3rd Law of motion). Also there is no correlation between hand speed at impact and clubhead speed.
DG
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Post by imperfectgolfer on Apr 19, 2023 22:20:30 GMT -5
Dr Mann If Milo's shaft and lead forearm were in a perfect straight line at P7.4, I would assume that the lead wrist angle would be 180 degrees. But if you look at his slow-mo driver swing post impact , it looks like he still has a lead wrist angle between lead forearm and shaft. Not all of the PC's graphs show a sharp peak before decreasing because some have a small plateau area which I assume would be from P7-P7.1 or P7.2 . I think any sharp decrease in lead wrist angle might be caused by radial deviation post impact into the follow-through. Phil Mickelson's lead wrist angle seems to reach about 170 degrees at impact similar to the image below and then decreases rapidly. We know he has a roller subtype Non-DH hand release action as per below Gif, so maybe it also involves increasing radial deviation immediately post impact. DG I reject your Milo Lines analysis because it is a DTL view that is subject to parallax distortion. One needs to view the lead forearm-clubshaft relationship from face-on - where the camera is perpendicular to the functional swingplane. Look at Domenic Mazza in image 2 where his lead wrist is more ulnar-deviated and where the lead wrist-clubshaft angle is larger in image 2 than image 1 (impact) and closer to 180 degrees.
Look at Matthew Fitzpatrick in image 4 where his lead wrist is more ulnar-deviated and where the lead wrist-clubshaft angle is larger in image 4 than image 3 (impact) and closer to 180 degrees. Look at Daniel Berger and note that his lead forearm-clubshaft angle is larger in image 4 than image 3 (impact) and closer to 180 degrees. Jeff.
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Post by dubiousgolfer on Apr 20, 2023 9:14:43 GMT -5
Dr Mann
The angle between the yellow lines on Milo's image is basically the PA3 angle post impact. If Milo was retaining an intact GFLW/LFFW in his downswing and through impact , wouldn't there still be an angle in the 'wedge' between lead forearm and shaft? There would have to be unless the lead forearm and club shaft were swinging instantaneously on the same plane and a line drawn from the forearm extended through the shaft.
Are you saying in image 2 for Domenic Mazza, image 4 for Fitzpatrick, image 4 for Berger , that their lead arm and club shaft are perfectly in line? That a longitudinal axis through their lead forearm would pass through the longitudinal axis of the shaft? If yes , then the lead wrist angle would be 180 degrees, but if not, then the angle would be less than 180 degrees.
DG
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Post by imperfectgolfer on Apr 20, 2023 9:19:30 GMT -5
Dr Mann I've listened to some of that SMK podcast and the interesting part was around -1:06:25 to -1:01:00 regarding a study by Chu on 308 amateur golfers. Apparently the wrist hinge angle (ie. angle between lead arm and shaft) at 40 msecs before impact (P6) showed the best association with clubhead speed than any other variable they measured at all the different points in the golf swings. The average wrist hinge angle was 145 degrees at p6 which gave a 140 mph ball speed and for every 10 degrees less angle between shaft and arm (ie. more lag), the ball speed would increase by 5mph. At -26:26 to -22:40 SMK says in the Chu study there was a wide range of wrist angles at P6 and ball speeds, but if you did that study on PGA pros (SMK has a database of 130) , you don't see much correlation. Just listening now to the question at -24:11 to -13:00 regarding how hand speed contributes to clubhead speed. Apparently hand speed should peak halfway between shaft vertical and shaft parallel on the downswing about 60 degrees from parallel. But increasing the peak hand speed might not necessarily have a correlation with clubhead speed (some paradox regarding Newtons 3rd Law of motion). Also there is no correlation between hand speed at impact and clubhead speed. DG I do not believe that maximum hand speed at ~P5.5 necessarily correlates with maximum clubhead speed at impact. Look at these kinematic sequence graphs. Note that JB Holmes has the highest clubhead speed at impact, but his maximum lead hand speed (blue graph peak) is small. Note that Rickie Fowler has the highest maximum lead hand speed, but his clubhead speed at impact is average. Also, consider these graphs. Note that Graham MacDowell and Phil Mickelson have much more clubhead lag at the start of their release - compared to Bryson Dechambeau and Rory McIlroy - but they obviously have lower maximum clubhead speeds at impact.
Jeff.
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Post by imperfectgolfer on Apr 20, 2023 9:39:53 GMT -5
DG, You wrote-: " The angle between the forearm and shaft would have to be measured from a viewpoint that is perpendicular to the instantaneous plane formed by those forearm/shaft lines. " Why are you doing the lead wrist angle measurements from a viewpoint that is perpendicular to the instantaneous plane formed by those forearm/clubshaft lines - rather than the viewpoint being parallel to the swingplane? Consider a golfer who uses a very strong lead hand grip where the back of his lead wrist/hand is continuously parallel to the swingplane between P4 => P7 and where the lead wrist uncocking action happens parallel to the swingplane. Would you not measure the lead wrist angle at P5, P6 and P7 in the same way - where the measurement is always made parallel to the swingplane? Consider a golfer who uses a very weak lead hand grip (like Will Zalatoris). Would you not measure his lead wrist angle at P5 and P6 in the plane of the swingplane if the back of the lead wrist is parallel to the swingplane at P5 and P6? What about impact when the back of the lead wrist is perpendicular to the swingplane? Jeff. Dr Mann I am just interpreting what Phil Cheetham implied in that video because he just mentioned the angle formed between the forearm and shaft viewed perpendicular to the plane formed by the forearm/shaft lines. With regard your example of a very strong lead hand grip where the back of the wrist is moving within the swing plane, the lead wrist angle measurement (as I have interpreted it from that video) would still be the angle formed between the shaft and forearm. And one would be able to see and measure the true angle only from a viewpoint which is perpendicular to the swingplane. The same as above would apply to Will Zalatoris if the back of his lead wrist was within the swingplane at P5 and P6. If the back of his lead wrist was perpendicular to the swing plane at impact and one still used the angle formed between the shaft and forearm as lead wrist measurement, then I can only assume that it's 180 degrees minus the PA3 angle. DG Here's an image which shows what I mean. DG, I noted that you have added this image showing how one should assess the lead wrist angle (lead forearm-clubshaft angle) near impact. If that is your opinion, then look at his image immediately post-impact. I have drawn a red line down his lead lower forearm and a green line along his proximal clubshaft - note that they are straight-line-aligned (= 180 degrees). Jeff.
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Post by dubiousgolfer on Apr 20, 2023 9:43:25 GMT -5
Dr Mann
For the sake of accuracy, the blue graphs do not show hand speed but angular velocity of the lead arm.
Velocity = Radius x Angular Velocity
So there is another variable, which is the radius, that can also affect the velocity of the hand. The radius variable could depend on the length of the golfers arm but also how it moves in 3D space (ie. its instantaneous centre of rotation). How they measure things in 3D has never been made clear enough for me to fully understand.
DG
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Post by dubiousgolfer on Apr 20, 2023 10:06:23 GMT -5
Dr Mann I am just interpreting what Phil Cheetham implied in that video because he just mentioned the angle formed between the forearm and shaft viewed perpendicular to the plane formed by the forearm/shaft lines. With regard your example of a very strong lead hand grip where the back of the wrist is moving within the swing plane, the lead wrist angle measurement (as I have interpreted it from that video) would still be the angle formed between the shaft and forearm. And one would be able to see and measure the true angle only from a viewpoint which is perpendicular to the swingplane. The same as above would apply to Will Zalatoris if the back of his lead wrist was within the swingplane at P5 and P6. If the back of his lead wrist was perpendicular to the swing plane at impact and one still used the angle formed between the shaft and forearm as lead wrist measurement, then I can only assume that it's 180 degrees minus the PA3 angle. DG Here's an image which shows what I mean. DG, I noted that you have added this image showing how one should assess the lead wrist angle (lead forearm-clubshaft angle) near impact. If that is your opinion, then look at his image immediately post-impact. I have drawn a red line down his lead lower forearm and a green line along his proximal clubshaft - note that they are straight-line-aligned (= 180 degrees). Jeff.
Dr Mann We seem to be talking about different angles . Are you referencing angles perpendicular to swing plane, because that isn't what I am doing ? I am just interpreting what I think Phil Cheetham seems to be using when he defines 'lead wrist angle' (although I've sent him an email to confirm but unsure whether he will have the time to reply). For example , here is Paul Wilson's driver swing just post impact from another angle . I have drawn a yellow line along his lead forearm and a red line through the top-half section of the shaft (note that there is quite a bend in the shaft and I've asked PC how they define the shaft line). I'm assuming the 'lead wrist angle' is as shown , but I cannot view the true angle from a viewpoint that is perpendicular to the plane formed by those 2 lines, but it's obviously not perpendicular to the instantaneous swing plane. DG
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Post by imperfectgolfer on Apr 20, 2023 10:21:33 GMT -5
DG, I noted that you have added this image showing how one should assess the lead wrist angle (lead forearm-clubshaft angle) near impact. If that is your opinion, then look at his image immediately post-impact. I have drawn a red line down his lead lower forearm and a green line along his proximal clubshaft - note that they are straight-line-aligned (= 180 degrees). Jeff.
Dr Mann We seem to be talking about different angles . Are you referencing angles perpendicular to swing plane, because that isn't what I am doing ? I am just interpreting what I think Phil Cheetham seems to be using when he defines 'lead wrist angle' (although I've sent him an email to confirm but unsure whether he will have the time to reply). For example , here is Paul Wilson's driver swing just post impact from another angle . I have drawn a yellow line along his lead forearm and a red line through the top-half section of the shaft (note that there is quite a bend in the shaft and I've asked PC how they define the shaft line). I'm assuming the 'lead wrist angle' is as shown , but I cannot view the true angle from a viewpoint that is perpendicular to the plane formed by those 2 lines, but it's obviously not perpendicular to the instantaneous swing plane. DG If I understand you correctly, you must be continuously changing the viewing angle between P6 => P7 so that can continuously assess the lead wrist angle in the plane of the radial => ulnar deviation. If not, you seem to have only one viewing angle at impact for golfers who may adopt a weak, neutral or moderately strong lead hand grip. Jeff.
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Post by dubiousgolfer on Apr 20, 2023 10:38:52 GMT -5
Dr Mann
Those lead wrist angle graphs aren't from AMM3D.
Here is the reply from PC.
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It is simply the angle between the forearm and the shaft.
Yes, you can also measure the wrist angled between the hand and the forearm, flex/extn, rad/ulnar dev, and forearm rotation (sup / pro) but they are more complex measurements that can be measured by AMM but not by Sportsbox at this time.
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DG
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Post by dubiousgolfer on Apr 20, 2023 10:48:07 GMT -5
Dr Mann
"If I understand you correctly, you must be continuously changing the viewing angle between P6 => P7 so that can continuously assess the lead wrist angle in the plane of the radial => ulnar deviation."
I suspect that is what Sportsbox AI system is generally doing.
DG
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Post by imperfectgolfer on Apr 20, 2023 11:16:28 GMT -5
Dr Mann "If I understand you correctly, you must be continuously changing the viewing angle between P6 => P7 so that can continuously assess the lead wrist angle in the plane of the radial => ulnar deviation." I suspect that is what Sportsbox AI system is generally doing. DG If your suspicion is true, then the Sportsbox lead wrist angles would better reflect reality for golfers who use a weak, neutral or a moderately strong lead hand grip. However, I still think that golfers, who adopt a very strong lead hand grip, can generate a 180 degrees lead wrist angle post-impact if they ulnar-deviate their lead wrist more post-impact. Jeff.
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Post by dubiousgolfer on Apr 20, 2023 11:48:30 GMT -5
Dr Mann
Looking at Ricky Fowler vs Bryson and Rory lead wrist angle graphs , doesn't it seem that RF has a significant early release? Basically , he is not retaining the lag angle late enough in the downswing (ie. P6) and probably not generating the amount of 'In Plane MOF' that Rory/Bryson is producing.
If you look at this RF video at P6 (0:52), I don't think he is extending his lead leg as well as Rory, because his lead foot is almost sliding/rolling onto its outside edge. I can guess he is not creating as much 'In Plane Net Force' across the club (ie. in a more vertical direction) like Rory at P6 (see video below at 1:01)
DG
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Post by imperfectgolfer on Apr 20, 2023 12:04:13 GMT -5
Dr Mann Looking at Ricky Fowler vs Bryson and Rory lead wrist angle graphs , doesn't it seem that RF has a significant early release? Basically , he is not retaining the lag angle late enough in the downswing (ie. P6) and probably not generating the amount of 'In Plane MOF' that Rory/Bryson are producing. If you look at this RF video at P6 (0:52), I don't think he is extending his lead leg as well as Rory, because his lead foot is almost sliding/rolling onto its outside edge. I can guess he is not creating as much 'In Plane Net Force' across the club (ie. in a more vertical direction) like Rory at P6 (see video below at 1:01) DG What? Here are the Sportsbox measurements of lead wrist angle.
RF retains a fixed 90 degree lead wrist angle during his early downswing until his PA#2 release point.
By contrast, Rory and Bryson have a 100 - 105 lead wrist angle at their PA#2 release point.
Jeff.
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