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Post by imperfectgolfer on Mar 20, 2022 13:36:40 GMT -5
Here is an interesting Kwon video where he reviews Ilhee Lee's golf swing action.
It is very interesting to see how many different measurements are being made by Kwon of different body part movements during a golf swing action.
What I found most controversial are his opinions expressed between the 35:00 - 44:30 minute time points of the video.
Kwon believes that if you have a faster, and more active, body motion during the backswing that it will allow a golfer to have a longer transition phase where the pelvis starts to rotate first before the upper torso/arms. He believes that a longer transition phase is advantageous. I can understand how that can increase the dynamic X-factor stretch, but I am not certain that a pro golfer will always benefit by having a longer transition phase.
Kwon also wants the angular velocity of the pelvic, upper torso and lead arm to peak simultaneously at P5, and he seemingly believes that it will result in increased clubhead speed due to a better transfer of energy from the body to the club. I do not understand his logic for this opinion, and I have noted that many pro golfers have a sequential peaking phenomenon where the angular velocity of the pelvis peaks before that of the upper torso/arms and where the angular velocity of the pelvis peaks between P5 => P5.5. I would be interested in learning whether Phil Cheetham and Sasho MacKenzie agree with Kwon's opinion on this issue.
Jeff.
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Post by dubiousgolfer on Mar 20, 2022 17:57:31 GMT -5
Dr Mann I doubt Dr Phil Cheetham/ Dr Greg Rose would agree with Dr Kwon's simultaneous peaking of the 'pelvis/thorax/shoulder line/lead arm ' angular velocities by club vertical position. DG I deleted my previous comments - nonsense! Here is an extract from the research article by Phil Cheetham and Dr Greg Rose www.researchgate.net/publication/252236426_Comparison_of_Kinematic_Sequence_Parameters_between_Amateur_and_Professional_Golfers"For best energy transfer and maximum club head speed in the downswing, the theory of proximal to distal sequencing (Putnam, 1993) requires several attributes to be evident in a golfer’s kinematic sequence; all segments should accelerate then decelerate before impact (except the club which should peak exactly at impact); the peaking order should be pelvis, thorax, arm, club; and each peak should be larger and later than the previous one"
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Post by imperfectgolfer on Mar 20, 2022 21:37:18 GMT -5
Dr Mann I doubt Dr Phil Cheetham/ Dr Greg Rose would agree with Dr Kwon's simultaneous peaking of the 'pelvis/thorax/shoulder line/lead arm ' angular velocities by club vertical position. DG I deleted my previous comments - nonsense! Here is an extract from the research article by Phil Cheetham and Dr Greg Rose www.researchgate.net/publication/252236426_Comparison_of_Kinematic_Sequence_Parameters_between_Amateur_and_Professional_Golfers"For best energy transfer and maximum club head speed in the downswing, the theory of proximal to distal sequencing (Putnam, 1993) requires several attributes to be evident in a golfer’s kinematic sequence; all segments should accelerate then decelerate before impact (except the club which should peak exactly at impact); the peaking order should be pelvis, thorax, arm, club; and each peak should be larger and later than the previous one"If you look at figure 1 in that article, the peaks are actually very close together - at P4.9 for pelvis, P5.1 for thorax and P5.2 for arms. Jeff.
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Post by dubiousgolfer on Mar 20, 2022 23:01:16 GMT -5
Yes , the peaks are close but definitely not happening at the same time and not at club vertical. I wouldn't know what the difference in clubhead velocity would be for 'peaking together' vs 'peaking slightly later'. DG
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Post by dubiousgolfer on Mar 21, 2022 8:21:19 GMT -5
Email exchange with Dr Rose
------------------- Dear Dr Rose
Sorry to bother you but was wondering which of the below would provide greater clubhead speed by impact (if timed correctly for both). The reason I am asking this question is that Dr Kwon prefers point 1 below (which has confused me somewhat).
1. A kinematic sequence where the angular velocities of the 'pelvis/thorax/shoulder line/lead arm' peak together by club shaft vertical in downswing . Obviously the magnitude of the peaks getting progressively larger from proximal to distal.
2. A kinematic sequence where the angular velocities peak larger and later from proximal to distal.
------------------
Reply:
Point 1 makes no sense - we would definitely tell you point 2 creates maximal speed. Everything peaking speed at the same time is not what we see with the biggest hitters in the world.
DG
PS. So there is no advantage from a clubhead speed perspective which means there must be another biomechanical reason.
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Post by imperfectgolfer on Mar 21, 2022 9:28:03 GMT -5
Here is Cheetham's presented collection of kinematic sequence graphs for multiple pro golfers. There is a large variation in patterns. Ernie Els and Luke Donald show the sequential sequencing pattern, but Rory McIlroy and JB Holmes have the peaks closer together.
Zach Johnson's arm graph peaks before his pelvis/upper torso graphs.
Jeff.
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Post by dubiousgolfer on Mar 21, 2022 11:01:05 GMT -5
Dr Mann
Yes there is quite a variation in the timing of the body segment peaks.
It seems that the pelvis peaks either before thorax or both together for most of them , exception being Johnson. But the arm peak timing seems to have quite a variation and that might be caused by the independent use of the shoulder girdle muscles which could affect its 3D angular velocity (which I think we've discussed before).
Maybe the slight variations of peaks between pelvis and thorax is affected by the independent contractions of the internal/external obliques. Couldn't they also have a similar effect on the 3D angular velocity of the ribcage?
DG
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Post by dubiousgolfer on Mar 22, 2022 9:17:04 GMT -5
Dr Mann
Here is my email exchange with Dr Greg Rose regarding the kinematic graphs.
DG ---------------------------------------------
Dr Rose
I have diagrams of several PGA pro kinematic sequence graphs ( I think they came from Dr Phil Cheetham) below. Although they follow the progressive larger angular velocity peaks from proximal to distal , the timing of the peaks seem to show large variations and don't all peak a little later (ie. from proximal to distal). In fact only Ernie Els and Luke Donald seem to follow point 2 in my previous email.
Is there a possible explanation for why there is such a variation in the timing of the peaks?
-----------------------
All those graphs were captured by me at TPI and I can tell you with certainty that over 50% of those all demonstrate point 2 (Els, Donald, Stricker, Spieth, Waite, Holmes and McIlroy). Just remember, just because you are on the PGA Tour doesn't mean you have an efficient kinematic sequence, and just because you don't have a good kinematics sequence does not mean you can't become a PGA Tour player. All it is measuring is how efficiently you generate speed and power. You can still be a great player and not have an efficient swing - just means you have to have another weapon. Like Ben Crane was the best putter on tour and Corey Pavin had an incredible wedge game - that is why they had great success on tour - not because of their swings.
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Post by imperfectgolfer on Mar 22, 2022 10:07:03 GMT -5
Dr Mann Here is my email exchange with Dr Greg Rose regarding the kinematic graphs. DG --------------------------------------------- Dr Rose I have diagrams of several PGA pro kinematic sequence graphs ( I think they came from Dr Phil Cheetham) below. Although they follow the progressive larger angular velocity peaks from proximal to distal , the timing of the peaks seem to show large variations and don't all peak a little later (ie. from proximal to distal). In fact only Ernie Els and Luke Donald seem to follow point 2 in my previous email. Is there a possible explanation for why there is such a variation in the timing of the peaks? ----------------------- All those graphs were captured by me at TPI and I can tell you with certainty that over 50% of those all demonstrate point 2 (Els, Donald, Stricker, Spieth, Waite, Holmes and McIlroy). Just remember, just because you are on the PGA Tour doesn't mean you have an efficient kinematic sequence, and just because you don't have a good kinematics sequence does not mean you can't become a PGA Tour player. All it is measuring is how efficiently you generate speed and power. You can still be a great player and not have an efficient swing - just means you have to have another weapon. Like Ben Crane was the best putter on tour and Corey Pavin had an incredible wedge game - that is why they had great success on tour - not because of their swings. I cannot understand Greg Rose's bold-highlighted claim that those TPI kinematic sequence graphs are only measuring how efficiently those pro golfers are generating speed and power.
What is the measure of efficiency? Surely it must be some parameter that causally accounts for a particular clubhead speed at impact? Which parameter is Rose looking at when defining "efficiency"?
Jeff.
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Post by dubiousgolfer on Mar 22, 2022 12:47:25 GMT -5
I imagine the parameter is energy.
I'm assuming Dr Rose and Dr Phil Cheetham are claiming that the kinematic sequence (they advocate) creates the conditions for a more efficient transfer of energy from proximal to distal.
DG
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Post by imperfectgolfer on Mar 22, 2022 17:28:54 GMT -5
I imagine the parameter is energy. I'm assuming Dr Rose and Dr Phil Cheetham are claiming that the kinematic sequence (they advocate) creates the conditions for a more efficient transfer of energy from proximal to distal. DG I find the concept of energy transfer from proximal => peripheral body segments incomprehensible. Jeff.
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Post by dubiousgolfer on Mar 22, 2022 20:11:31 GMT -5
I have found a huge thesis on kinematic sequence (magnitude and timing) which does throw doubt on Dr Rose/Cheetham opinion that the timing of the peak angular velocities follow a pure proximal-distal pattern. The author is using an analysis of the kinetic energy of body segments rather than measurement of angular velocities. shura.shu.ac.uk/23514/1/10760411.pdfI've skimmed through it but it seems to conclude (from the diverse sample of golfers used) that the angular velocities segment kinetic energies of the lower and upper body and arms peak at the same time. But it gets quite complicated as he is using body segment energies (translational kinetic energy and something called local/remote rotational kinetic energies). "These studies (Cheetham etal., 2008; Neal, et al., 2007) appear to present similar findings which have practical relevance for less skilled players and support the existence of the proximal-to-distal sequence. However, the results of both studies were not supported by statistical analyses. Closer inspection of the results actually indicated that peak thorax and peak upper arm angular velocity occurred at a similar time (Table 2.1).""However, the magnitude of peak segment KE for each component did not occur in a proximal-to-distal order as the results highlighted the importance of producing translational Legs and local rotational Upper Body KE. The results of Chapter V also indicated that club type had a significant effect on the golf swings of highly skilled players. Specifically, the results indicated that skilled golfers produced larger peak translational Arms KE and peak local rotational Upper Body KE when the distance requirement of the shot increased""With all three clubs, the timing of peak total KE conformed to the principle of optimal coordination of partial momenta as peak total body segment (Lower Body, Upper Body and Arms) KE peaked simultaneously at approximately 74% MT whilst total club KE peaked just before impact. However, regardless of club type, sequential timing was evident for the translational and rotational components of segment KE from the Upper Body to the Club. Finally, the results suggested that when the driver was used and the distance requirement of the shot increased, peak translational Lower Body and Upper Body KE occurred significantly later in the swings of highly skilled golfers.""For all playing standards, peak total KE for the body segments occurred simultaneously whilst peak total Club KE occurred significantly later in the downswing just before impact. Despite these similarities, significant differences were identified between the timing of body segment movements in the golf swing. The results highlighted the importance of a sequence of translational KE from the Upper Body to the Club and of an early peak in local rotational Upper Body KE as these movement strategies were only used by category 1 golfers. It was suggested that these movement strategies enabled skilled golfers to generate increased total Club KE via the kinetic link principle and stretch shortening cycle."There is also an interesting section on Front Foot and Reverse Foot golfers p139 "7. Chapter VII - The Effect of Weight Transfer Style on the Sequencing of Segment Kinetic Energy in the Golf Swings" DG PS. I found most of this thesis incomprehensible and a mental strain but I might take a few months to try and read through it in more detail. He has reviewed all previous research articles (including Dr Cheetham) and provided his own opinions on possible flaws in the methods used. I need to understand what the underlined parts are in his chapter summaries. MT means segment movement time. Found an explanation already for the 'principle of optimal coordination of partial momenta'. "Van Gheluwe and Hebbelinck (1985) proposed the principle of optimal coordination of partial momenta. This principle states that optimal distal end velocity of a linked system is reached when the angular velocities of the segments peak simultaneously or in an order specific to an individual, not in a proximal-to-distal sequence. It is also known that the speed of the distal end of any rotating body, pivoted at its proximal end is equal to the length of the body multiplied by the body's angular speed. Therefore, from a purely kinematic perspective, it appears logical that all segments with appropriate positioning should be rotating with maximum speed when maximum distal end speed is desired (Putnam, 1993)."
"the principle of optimal coordination of partial momenta (Van Gheluwe and Hebblinck, 1985). The three human based segments (Lower Body, Upper Body and Arms) peaked simultaneously at approximately 80% of the downswing movement time whilst peak club segment KE occurred significantly later in the swing, just before impact.
"The different timing sequences reported in the analyses of segment KE and segment angular velocities may be caused by analyses of segment KE considering the translational movements of body segments. It is possible that the translational movements of the lower body, trunk and arms segments which have been highlighted as important components of skilled golf swings (Beck etal., 2013; Hume, Keogh and Reid, 2005; Nesbit and McGinnis, 2009) do not conform to the proximal-to-distal sequence. The different timing sequences may also be explained by examining the segments involved in each type of analysis. The analyses of segment KE were able to consider the motion of every body segment involved in the golf swing whilst the kinematic analyses considered the motion of much fewer segments. More specifically, the contribution of the legs and the right arm were considered in the KE analyses (Anderson, Wright and Stefanyshyn, 2006; Kenny et al., 2008) whilst the majority of kinematic analyses ignored these segments (Cheetham etal., 2001; Teu etal., 2006; Tinmark et al., 2010; Vena et al., 2011b). Furthermore, only Neal et al. (2007) considered the angular velocity of all the segments comprising the lead arm. Most other studies only considered the more distal segments such as the hand"
"The majority of these analyses have suggested that skilled golf swings are underpinned by proximal-to-distal sequences of segment angular velocities (Cheetham etal., 2008; Neal etal., 2007; Tinmark etal., 2010). However, as translational movements accounted for approximately half of the total KE produced by each segment (Figure 5.4) the results of this study suggest that by only examining the rotational movements of body segments these studies did not account for a large proportion of golfer's movements."
"Therefore, although peak total segment KE conformed to the principle of optimal coordination of partial momenta (Van Ghelwe and Hebblinck, 1986) these results indicate that highly skilled golf swings are underpinned by sequential increases in translational and rotational components of segment KE from the Upper Body to the Club."
Conclusion
In conclusion, a proximal-to-distal sequence was evident in the magnitude of peak total segment KE when all three clubs were used. However, the magnitude of peak segment KE for each component did not occur in a proximal-to-distal order as the results highlighted the importance of producing translational Legs and local rotational Upper Body KE. Club type also had a significant effect on the magnitude of peak total KE as more energetic golf swings were produced with the driver. More specifically, skilled golfers produced larger magnitudes of translational Arms KE and local rotational
Upper Body KE when the distance requirement of the shot increased. With all three clubs, the timing of peak total KE did not occur in a proximal-to-distal sequence which suggested that the timing of peak total KE conformed to the principle of optimal coordination of partial momenta. However, the results suggested that this regardless of club type, highly skilled golf swings were underpinned by sequential translational and rotational movements from the Upper Body to the club. Finally, the results suggested that when the driver was used and the distance requirement of the shot increased, peak translational Lower Body and Upper Body KE occurred significantly later in the swings of highly skilled golfers.
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Post by imperfectgolfer on Mar 22, 2022 23:40:14 GMT -5
DG - that's going to be a long read. I will look at it sometime in the future.
Ask Greg Rose what he thinks of that author's conclusions.
Jeff.
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Post by dubiousgolfer on Mar 24, 2022 19:30:58 GMT -5
Here is Dr Kwon instructing Ben Crane and he mentions at 23:30 "if you lose the balance that means your arms are quite active, so in that case you can use your wrist a bit more. So as you swing down try to use your wrist more. Then what happens is the the body turn slows down with the wrist action." "snapping something with a wrist action. Then body turn will be less, so it will slow down and you will have a stable finish position" "you don't lose your balance if you use your wrists more" I cannot understand Dr Kwon's reasoning behind this because we know that active wrist torque in the downswing will need to be perfectly timed otherwise it will have an adverse effect on clubhead speed at impact. Also we know that the wrists cannot keep up with the angular velocity of the club which is why there is negative torque after ~P6 so why bother trying to create a 'snapping effect'? Wouldn't an active wrist torque tend to create a clubface flip action through impact and an increased ROC? How can an active wrist torque slow the body down? It doesn't make any sense because: 1. An active wrist torque will be very small and will have a negligible affect on the body. 2. Unless I'm mistaken, an active lead wrist torque in the downswing will slow the arm down , but this will actually cause the lower body to marginally increase its rotational speed, not slow it down (especially if the spine is assumed to be rigid without much range of rotation). It might slow the pelvis down if certain areas of the spine are quite flexible from a rotational perspective and can act like a joint between spine and pelvis. He tries to explains the physics of this at 33:08 but that makes no sense to me because active snapping wrists are creating torque on the grip not trying to push the club towards the target (of course I could be mistaken). He says: "When the body tries to throw the club, the body pushes the club that way , the club is pushing the body in the opposite direction, so it will slow down the body while you try to accelerate the arms and club, so that's why your body slows down" The above makes sense but that's when you try to accelerate the arms and has nothing to do with the activation of independent wrist torque (if that's what snapping of the wrists mean). DG PS. Trying to work out how a torque created in one segment of a human body affects another part is quite tricky, especially when the shoulder girdle and spine is involved. For example , if a golfer has a very flexible spine can one assume there are areas that can act like a joint (ie. especially in the thoracic region)?
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Post by syllogist on Mar 25, 2022 7:23:41 GMT -5
Hi DG,
Just watched the sections of the video you noted. My simple summary of Dr. Kwon's teaching in this video: Full turn in backswing, rapid turn during downswing only when the torso remains centered in space (one spins a ball on a string held by the thumb and index finger efficiently in a very tight circle.), and not to actively engage the arms during the downswing.
I don't disagree with any of his points. As for his comment about the wrists, I don't think that he meant to try to actively extend the wrists in the downswing. Recall how he said to "let go." I think that if the torso and then the arms both slow (cease accelerating) during the later stage of the downswing, the wrists will sufficiently "let go," or "release."
S
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