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Post by imperfectgolfer on Jan 1, 2022 17:55:56 GMT -5
Here’s a thought on what Dr Kwon may mean by using the legs: Let’s imagine a heavy kettle bell or sledgehammer, say 10kg. Have a subject hold it with both hands. Then raise it up with an assist crane to a top of backswing position. Then with some other mechanical machine have it be forced downwards in a normal swing path. Who would be more likely to be pulled off balance and fall forward; a man or woman? So my hypothesis is that due to leg strength, men are ‘enabled’ to swing the mass of the club at higher speeds, as they have a stronger ability to counter balance the momentum. How do male pro golfers swing their driver faster if they have the same pelvic rotation speed, same upper torso rotation speed and same lead arm release speed as female pro golfers? Stronger legs may enable them to better maintain their balance through impact at the higher clubhead speed, but how do they actually produce a higher clubhead speed at impact? Jeff.
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Post by dubiousgolfer on Jan 1, 2022 18:03:18 GMT -5
Here’s a thought on what Dr Kwon may mean by using the legs: Let’s imagine a heavy kettle bell or sledgehammer, say 10kg. Have a subject hold it with both hands. Then raise it up with an assist crane to a top of backswing position. Then with some other mechanical machine have it be forced downwards in a normal swing path. Who would be more likely to be pulled off balance and fall forward; a man or woman? So my hypothesis is that due to leg strength, men are ‘enabled’ to swing the mass of the club at higher speeds, as they have a stronger ability to counter balance the momentum. Dr Kwon believes that ground reaction forces by use of the lower body are responsible for generating angular momentum in the golfers body and generating clubhead speed. Dr Sasho MacKenzie suggested that golfers early extension use vertical ground reaction forces to counter the dynamic weight of the club and control the momentum of the club through impact , especially in the lead foot. He also states that golfers maximising their vertical ground reaction force in their lead foot at shaft vertical in the downswing is a key indicator to the generation of clubhead speed. DG
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Post by imperfectgolfer on Jan 1, 2022 18:39:43 GMT -5
Here’s a thought on what Dr Kwon may mean by using the legs: Let’s imagine a heavy kettle bell or sledgehammer, say 10kg. Have a subject hold it with both hands. Then raise it up with an assist crane to a top of backswing position. Then with some other mechanical machine have it be forced downwards in a normal swing path. Who would be more likely to be pulled off balance and fall forward; a man or woman? So my hypothesis is that due to leg strength, men are ‘enabled’ to swing the mass of the club at higher speeds, as they have a stronger ability to counter balance the momentum. Dr Kwon believes that ground reaction forces by use of the lower body are responsible for generating angular momentum in the golfers body and generating clubhead speed. Dr Sasho MacKenzie suggested that golfers early extension is used to counter the dynamic weight of the club . DG Soon afterwards, Boditrak removed both the video and the article from its golf instructional collection and I presume that they were embarrassed by the fact that Sasho was arguing in defense of an "early extension maneuver" as being an advantageous maneuver in a pro golfer's golf swing action. Jeff.
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Post by dubiousgolfer on Jan 1, 2022 19:13:30 GMT -5
Dr Mann
Looks like Jay Dubeck who is posting comments on Dr Kwon's you tube videos needs to calm down a bit.
DG
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Post by dubiousgolfer on Jan 1, 2022 22:13:46 GMT -5
Dr Mann
You said:
"How do male pro golfers swing their driver faster if they have the same pelvic rotation speed, same upper torso rotation speed and same lead arm release speed as female pro golfers? Stronger legs may enable them to better maintain their balance through impact at the higher clubhead speed, but how do they actually produce a higher clubhead speed at impact?"
If LPGA/PGA players are doing similar amount of 'Linear Work' on the club up to release, then the only way that PGA players can generate more clubhead speed would be via these mechanisms below to increase the angular velocity of the club.
1. Increased 'In Plane Mof' 2. Active wrist torque
We know from inverse dynamic graphs (ie. shown on the Dr Sasho Mackenzie video 'In-Plane Couple and Moment of Force During the Golf Swing') that hand couple goes negative just after P6 so there is virtually no time between release P5.5 and P6 to generate any increased angular velocity by using active positive wrist torque.
We are really only left with point 1 .
A larger 'In Plane Mof' can be achieved by the below:
3. A larger 'In Plane' net force across the club 4. A larger 'Moment Arm'
DG
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Post by imperfectgolfer on Jan 2, 2022 13:11:19 GMT -5
Dr Mann Looks like Jay Dubeck who is posting comments on Dr Kwon's you tube videos needs to calm down a bit. DG DG, I don't personally know Jay Dubeck, but I am very used to the phenomenon of insulting personal ad hominem attacks being made by uncivilized posters in the comments section of you-tube videos. Let's consider Jay's hypothesis that male pro golfers are going to automatically have a higher clubhead speed at impact than female pro golfers because they are muscularly stronger. He used Justin Thomas as an example. Justin Thomas has a slender physique, and he does not exhibit much muscular bulk. However, that does not matter because there is no direct correlation between muscle strength and muscle mass, so Justin Thomas could have a lot of muscle strength despite not being a bulky individual. How could Justin Thomas' inherent muscle strength produce a very high clubhead speed at impact in his driver swing? I am sure that you agree that muscle strength is a major factor that can potentially increase the speed of release of PA#4 in a pro golfer, who uses a pivot-induced TGM (lead arm) swinging action like Justin Thomas (and most pro golfers) - by potentially increasing the speed of pelvic and upper torso rotation that moves the lead shoulder socket and thereby the lead arm and by increasing the downward component of the PA#4 release action by efficiently using the shoulder girdle muscles. All those factors can increase the linear work that is being performed by the lead hand on the club handle between P4 => P5.5/P6. Here is Sasho's (SMK's) image showing the amount of force being applied to the driver's club handle by the lead hand and the total amount of linear work being performed during the early-mid downswing by P6 by a major PGA tour winner. Note that it required 134.3J of work to move the club handle down to the P6 position. This linear work calculation is based on inverse dynamics calculations, and it is not a measure of the golfer's muscular strength in terms of torso pivot power and/or arm power. It simply states that to move the club handle down the hand arc path by that distance and at that speed of motion, a finite (measured) amount of work effort must have been performed by the hands at the level of the club handle. Now, if a female pro golfer can get the driver's club handle down to the P6 position while covering the same amount of hand arc travel distance in the same amount of time, then the amount of work being exerted at the level of the club handle by the hands must be the same - even though female pro golfers obviously have less muscular strength than male pro golfers. That is seemingly what Zheng discovered in his comparative study - www.researchgate.net/publication/5292347_Swing_Kinematics_for_Male_and_Female_Pro_Golfers - of PGA versus LPGA golfers. Here again are his results. He demonstrated that there is no significant difference in the angular velocity of pelvic rotation, upper torso rotation and lead arm relative to trunk motion between male PGA pro golfers and female LPGA pro golfers, and the only significant difference was in the speed of lead wrist uncocking (which mainly happens after P5.5).
Zheng has another table (table 3) in his paper where he showed the timing results of body/arm motions in terms of when they reached they reach their maximum angular velocity. He showed that the lead arm-to-trunk timing was the same for LPGA versus PGA pro golfers. That suggests that female pro golfers can release PA#4 (release the lead arm) at the same speed as male pro golfers even though they have less muscular strength. How is that possible? I think that the answer probably lies in the fact that we need to factor-in the flexibility/mobility of body parts/joints in female pro golfers versus male pro golfers; and I suspect that female pro golfers make up for their lack of muscular strength by being more flexible/mobile and that fact seemingly enables them to get their driver club handle down to the P6 position with the same degree of efficiency (in terms of the linear work effort that is measured at the level of the club handle) as male pro golfers.
However, as Jay Dubeck pointed out, Justin Thomas (as an example of a male pro golfer) can generate a higher driver clubhead speed at impact than a comparable female pro golfer example. How is this possible if the "average" amount of linear work being exerted on the club handle between P4 => P5.5 by a male PGA pro golfer is not more than the "average" amount of linear work being exerted on the club handle between P4 => P5.5 by a female LPGA pro golfer? Jay Dubeck is free to join this golf forum and post an answer to this question. I personally suspect that the major reason why male PGA pro golfers can generate a higher clubhead speed at impact in their driver swings than female LPGA pro golfers is related to the fact that they can release PA#2 (release the club) more efficiently - as shown in Zheng's study where the angular velocity of club release was 1140 degrees/second in male pro golfers versus 816 degrees/second in female pro golfers.
What factors are in play that can potentially increase the speed of release of PA#2? Both Kwon and SMK seemingly have the same opinion that it is the MoF that is primarily responsible for causing the optimum release of PA#2 between P5.5 => impact. Here is Kwon's graph of the club torques in male tour pro golfers, teaching pro golfers and junior/collegiate golfers. That representative male golfer in the above image is at the ~P6 position, which is equal to the "4 MD" position, which is difficult to see in this image, but it is at the ~80% level on the horizontal axis.
Note that the MoF (green graph) increases dramatically after P6 and both Kwon/SMK have stated that it is the major causal factor responsible for the speed of release of PA#2. I have never seen Kwon present comparable MoF graphs for female tour pro golfers, so I do not know if there is a significant difference in their MoF graph. If there is, then one needs to provide a rational explanation as to i) what biomechanical factors are causing that difference in MoF (happening after P5.5) between male pro golfers versus female pro golfers and ii) whether "muscular strength" differences between male versus female pro golfers could be playing a role in any MoF differences. If Jay Dubeck (or any other person) has any insight into this issue, he is free to join this golf forum and post his opinions (+/- supportive scientific evidence). Could male pro golfers be producing a faster PA#2 release phenomenon than female pro golfers by actively releasing PA#1 (actively straightening their trail arm and trail wrist ) in such a manner that it increases the positive force-across-the-shaft being exerted by the trail hand between P5.5 => impact? Note that Zheng showed that the speed of right wrist straightening and right elbow extension was much greater in male pro golfers (to a highly significant P value of 0.002). However, I think that it is not possible because both Kwon/SMK have shown that the trail hand couple's force-across-the-shaft (see red graph in the Kwon torque image) is decreasing rapidly in the later downswing and that it becomes frankly negative before impact. If Jay Dubeck (or any other person) believes otherwise, he is free to join this golf forum and freely post his personal opinions in this thread. Jeff.
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Post by imperfectgolfer on Jan 2, 2022 18:19:23 GMT -5
Consider these further comments made by Jay Dubeck in the comment section of that Kwon video-: " Men produce more optimal work and power then women because they are stronger. It's kinda obvious in most sports where major muscle activity is used! It's not the wrist joints as you seem to think. The men are able to transfer more energy to the club and one of the main reasons is they are stronger, it's not the only reason but it's a major factor.
If you compare elite to elite the men out drive the women it's no contest, why do you think the top long drive men out drive the top long drive women? Is it just because of wrists or legs, arms, technique or is it because men are stronger in all those area's?" First of all, consider this statement that Jay expressed-: "It's not the wrist joints as you seem to think". I never implied that swing power in a driver golf swing action is mainly due to release of PA#2. I simply stated that when interpreting Zheng's research study comparison of LPGA female pro golfers versus PGA male golfers that there was no comparative difference in factors that modulate the efficiency of release of PA#4 - speed of pelvic rotation, speed of upper torso rotation and speed of release of the lead arm via muscular contraction of shoulder girdle muscles. The major difference was in the speed of release of PA#2.
Secondly, I have never concluded that the same comparative results would be found in a comparison between male long-drive competitors and female long-drive competitors (who cannot drive the ball as far.) I know of no comparative study similar to the Zheng study and I would not be surprised to discover that male long-drive competitors release PA#4 much more efficiently than female long-drive competitors because they are stronger from a muscular perspective. It seems obvious to me that having more pelvic girdle and torso muscular power to rotate the pelvis and upper torso very fast between P4 => P5.5+ and having more shoulder girdle muscle power to optimise the downward component of the release of PA#4 will be potentially advantageous in terms of maximising clubhead speed at impact.
Jay Dubeck also wrote in his reply to PS Smith (DG)-: "maybe you and Mann should read Nesbit's WORK AND POWER paper. It shows where the power is produced and the woman in that paper is behind in almost every aspect of the swing compared to the men.Even though they are all amateurs she is a 18 hdcp and 1 male golfer is an 11 hdcp."
That specific comment shows that Jay is a gross "amateur" when it comes to interpreting the validity of golf swing research literature articles. David Tutelman, Kwon and SMK have all demonstrated that the Nesbit study is highly flawed. Jay should get better educated by first reading this article by David Tutelman - www.tutelman.com/golf/swing/nesbitKwon1.php - and he should then follow the links to more David Tutelman articles relating to this issue. Jeff.
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Post by dubiousgolfer on Jan 3, 2022 7:17:47 GMT -5
Dr Mann
In that kinematic research article LPGA vs PGA , it says that the maximum velocity of the right elbow extension happens at around 97/98 % of the downswing. Further ,at impact LPGA women have their right shoulder slightly more orientated towards target and slightly more right elbow flexion. Can one assume that it's the superior angular momentum of the PGA club (due to more efficient release of PA#2) that is pulling their right arm slightly more straighter but significantly quicker near impact (maybe between P6.7-P7)?
DG
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Post by imperfectgolfer on Jan 3, 2022 10:13:44 GMT -5
Dr Mann In that kinematic research article LPGA vs PGA , it says that the maximum velocity of the right elbow extension happens at around 97/98 % of the downswing. Further ,at impact LPGA women have their right shoulder slightly more orientated towards target and slightly more right elbow flexion. Can one assume that it's the superior angular momentum of the PGA club (due to more efficient release of PA#2) that is pulling their right arm slightly more straighter but significantly quicker near impact (maybe between P6.7-P7)? DG I don't think one can definitively come to that conclusion because of the confounding variable of the variable position and variable speed of motion of the trail shoulder relative to the targetwards speed of motion of the lead hand during the P6 => P7 time period. It also probably depends on how passively relaxed the trail arm is during the trail arm straightening phenomenon and whether the golfer intentionally decides to use a DH-hand release action where he intentionally keeps the trail arm/wrist less straightened to well beyond impact - as seen in these following capture images of Cameron Champ.
Jeff.
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Post by dubiousgolfer on Jan 3, 2022 12:43:40 GMT -5
Many thanks Dr Mann
DG
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Post by dubiousgolfer on Jan 4, 2022 19:26:36 GMT -5
Dr Mann
Do you agree with this video regarding pelvic tilt? This seems to make sense about how the obliques contract, reduce lordosis in the backswing and downswing and help turn the upper torso . It also contradicts Dr Kwon's belief that the lower body is mainly responsible for generating clubhead speed, therefore I do not understand how such a well renowned biomechanics scientist can still hold this opinion.
DG
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Post by dubiousgolfer on Jan 4, 2022 20:35:50 GMT -5
Looks like Dr Kwon has just released another video so maybe this might provide a better insight about why he believes lower body mainly responsible for generating clubhead speed (viewing it now as I post this).
DG
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Post by imperfectgolfer on Jan 5, 2022 10:35:54 GMT -5
Dr Mann Do you agree with this video regarding pelvic tilt? This seems to make sense about how the obliques contract, reduce lordosis in the backswing and downswing and help turn the upper torso . It also contradicts Dr Kwon's belief that the lower body is mainly responsible for generating clubhead speed, therefore I do not understand how such a well renowned biomechanics scientist can still hold this opinion. DG I generally agree with the opinion that a pro golfer should have anterior pelvic tilt between P4 => P5 (end of hip-squaring phase = Sam Snead squat position). The amount of anterior pelvic tilt may sometimes increase if the golfer increases his degree of hip joint flexion between P4 => P5 causing the head to drop (eg. Rory McIlroy and Tiger Woods). Between P5 => P5.5, the lead leg is going to start to straighten and the trail buttock is going to start to leave the tush line, and that should result in a progressive move towards posterior pelvic tilt, which should increase in degree between P5.5 => P7. I don't believe that the lower torso's counterclockwise rotation is primarily responsible for the pivot motion's being causally responsible for increasing clubhead speed (via the release of PA#4) because it does not directly move the left shoulder socket. The left shoulder socket moves targetwards when the upper torso starts to rotate counterclockwise after a variable degree of torso-pevic separation. However, the lower torso must lead the upper torso throughout the downswing to prevent an OTT move. The lower torso's rotational speed usually peaks close to ~P5.5 and during the P4 => P5.5 time period, the pelvis is still mainly in a condition of anterior pelvic tilt. Jeff.
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Post by imperfectgolfer on Jan 5, 2022 11:08:49 GMT -5
Looks like Dr Kwon has just released another video so maybe this might provide a better insight about why he believes lower body mainly responsible for generating clubhead speed (viewing it now as I post this). DG I think that Kwon's abstract theorising is worthless from a practical golf instructional perspective. Kwon is basically asserting that the vertical GRF's being produced under the two feet are causally responsible for causing the torso to rotate counterclockwise in the frontal plane around an imaginary COM (which is not even situated within the torso but is located within an imaginary space in front of the mid-torso) and where the axis of rotation is parallel to the ground. However, a "real life" golfer rotates his pelvis/mid-torso in a much more horizontal plane where the axis of rotation is more vertical and situated roughly midway between the two feet.
I agree with Kwon's practical golf instructional teaching where he teaches a back-and-forth pelvic rotary motion where the pelvis is rotating roughly horizontally with only a small degree of natural hip joint elevation (where the golfer develops a negative O factor at P4 and a positive O factor at impact due to a variable degree of trail leg and then lead leg straightening respectively). When Kwon taught Brendon, he never once talked about generating vertical GRFs under the feet in order to rotate the torso in a vertically-oriented frontal plane where the axis of rotation is through an imaginary COM and where the axis is horizontal to the ground. Also, Kwon featured two graphs of torque values for two golfers in his video (see 10:22 minute time point of the video) that were totally unlike each other in terms of graph shape or torque magnitude. What is the practical value of even measuring those torques values? Common sense dictates to me that if a golfer has a vertical-or-leftwards centralised upper torso loading pattern during his backswing (player 1) and another golfer has a rightwards-centralised upper torso loading pattern during his backswing (player 2), that they will likely have different torque values when it comes to torque-rotating the pelvis/upper torso during the downswing. However, any torque measurement has no "real life" golf instructional value because it is a totally abstract measurement and it does not take into account that pro golfers in "real life" are significantly using muscular forces (pelvic girdle muscles and abdominal oblique and back muscles), and not vertical GRFs, to rotate their pelvis and upper torso during the downswing. Jeff.
p.s. By the way, I am not surprised that Jeff Martin made a positive comment in the comments section of Kwon's video.
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Post by imperfectgolfer on Jan 5, 2022 11:36:22 GMT -5
Michael Sliwinski made the following comment in the comments section of Kwon's video-: " Hmmm. Interesting but surprising to me that no discussion of the forces etc provided by upper body, shoulders arms wrists and hand has been discussed here." Kwon replied as follows-: " It is not possible to accurately measure the force provided by the upper trunk, shoulders, arms, wrists, and hand as these body parts for a closed chain in golf swing." That is a major problem!!! If the only torque force that is truly measurable are the GRFs produced under the feet, then it is obvious that one could incorrectly conclude that these GRFS are causally responsible for causing rotation of the torso. However, from a "real life" golf instructional perspective, one needs to teach a student-golfer how best to biomechanically move the i) body (pelvis + upper torso) and the ii) arms and the iii) wrists/hands.
Kwon did a good job in teaching Brendon Devore how to biomechanically perform number i), but he had nothing useful to say about ii) and iii).
Jeff.
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