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Post by dubiousgolfer on Jul 11, 2017 19:01:32 GMT -5
Dr Mann I am in discussion about the intact 'Left Arm Flying Wedge' where certain posters are saying the following: "Left arm flying wedge is not maintained. Wrist angles are changing significantly in the golfswing, both flexing and extending" "The lead wrist is constantly changing its amount of flexion/extension and is rapidly extending through impact." " AMM 3D captures of tour players show that lead wrist is extending rapidly" I have asked where one can find this measurement data and whether its over a large sample of pga pros but I don't think it will be made readily available. Are you aware of any data that has measured the amount of extension/flexion of the left 'hand/wrist' over a large sample of pga pros? PS. This graph on your website does show a green line showing (what I assume to be) angular velocities of the lead wrist extension-flexion for the downswing but what does it show to be happening? Does it show that there is very little change in angular velocities in left wrist extension/flexion up to release (maybe a little increased flexion)? That maybe near P6.5 there is a bit more 'Flexion' and then an increased extension (from the Flexion position at 6.5) to get a FLW at impact? Have I interpreted this green lined graph correctly?
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Post by imperfectgolfer on Jul 11, 2017 22:58:59 GMT -5
You wrote-: "I am in discussion about the intact 'Left Arm Flying Wedge' where certain posters are saying the following: "Left arm flying wedge is not maintained. Wrist angles are changing significantly in the golfswing, both flexing and extending"
Where is this discussion happening? Could you please link me to the discussion?
Jeff.
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Post by dubiousgolfer on Jul 12, 2017 4:19:59 GMT -5
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Post by imperfectgolfer on Jul 12, 2017 15:07:51 GMT -5
Most of the posters at GolfWRX are critical of me and that particularly applies to Fort Worth Pro and Dan Carraher who harbor a great deal of personal antipathy with respect to me. I am used to their personal ad hominem attacks and I am also used to their mental blindness when considering their wrongheaded thinking regarding the intact LAFW concept and the DH-hand release concept. I actually joined the GolfWRX under an alias name to counter Dan Carraher's wrongheaded opinions regarding this topic - see this thread at newtongolfinstitute.proboards.com/thread/580/carraher-misrepresents-golfwrx-forum-threadWhen I debated this topic in the GolfWRX thread (which has now been removed from their website), both Fort Worth Pro and Dan Carraher argued that the left wrist is extending rapidly and massively through impact. I argued that any left wrist extension happening between P7 and P7.2 in a DHer was insignificant (which I arbitrarily defined as < 5 degrees of extension) and I offered a $100 donation to any person who could show that it is possible to prevent the clubshaft from bypassing the left arm if the amount of left wrist extension happening between P7 and P7.2 is >5 degrees. I used this image to make that point. I drew those black lines on the back of my left hand's 2nd metacarpal bone and over the radial bone at the level of the left wrist to measure the degree of dorsiflexion of my geometrically flat left wrist at impact, and it measured 144 degrees in image 1. I then kept an intact LAFW/GFLW and I then moved my clubshaft to the P7.2 position (image 2) where the clubshaft is still straight-in-line with my left arm (from an angular rotational perspective). You can see that it measured 142 degrees (which means that the degree of left wrist dorsiflexion is roughly unchanged). I then deliberately extended my left wrist by 5 degrees (to 137 degrees) and you can see that it caused my clubshaft to bypass my left arm (image 3). I offered $100 to any person who could extend their left wrist by >5 degrees between P7 and P7.2 and still prevent the clubshaft from bypassing their left arm - as routinely seen in golfers who are DHers - but no one has taken up the challenge. I also posted these two graphs showing that the left wrist moves in the direction of a greater degree of flexion in the late downswing, and that "fact" contradicts Dan Carraher's (and Fort Worth Pro's) claim that the left wrist is extending rapidly between P6 and impact. Graph 1 from Phil Cheetham's PhD dissertation paper. Graph 2 from this research study - www.academia.edu/3051161/WRIST_KINEMATICS_DURING_THE_GOLF_DRIVE_FROM_A_BILATERALLY_ANATOMICAL_PERSPECTIVEI then asked to see the "3-D evidence" that Fort Worth Pro claimed would demonstrate that the left wrist is extending rapidly from P6 to P7 (and beyond P7 to P7.2+), but he didn't provide the "evidence", and I was banned from the Golf WRX forum a few hours after asking for the "evidence". Jeff.
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Post by dubiousgolfer on Jul 13, 2017 6:07:44 GMT -5
Dr Mann - many thanks for your detailed reply above. I suspect there is no point in me trying to post your reply on GOLFWRX as I will probably get banned too but I will advise interested forum members that a response to their assertions are on this website.
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Post by imperfectgolfer on Jul 13, 2017 9:19:58 GMT -5
Dr Mann - many thanks for your detailed reply above. I suspect there is no point in me trying to post your reply on GOLFWRX as I will probably get banned too but I will advise interested forum members that a response to their assertions are on this website. Yes - you need to be careful about posting my personal comments directly on the GolfWRX.com website because that will likely get you banned. Here is Dan Carraher's latest post in that GolfWRX forum thread-: " So you're going to argue it's extending before impact and after impact but isn't extending through impact? That's not how physics work. It's extending rapidly and very linearly. Phil can't give you an exact number over a milliseconds time but he can certainly tell the direction it's moving. And it's not looking at 3D photos. It's measured data plotted on a graph. You think a 3D system measuring 250-400fps is less accurate than Jeff can deduce from 2D video at SLOWER frame rates?
The second graph absolutely is NOT showing both wrist flexing. It's showing left wrist extending and right wrist flexing. They are both moving in the same direction. You don't understand what the graph is showing. It's supports my position. The positive direction is towards the target (left wrist extension/right wrist flexion). Negative is the opposite." When did you argue that the left wrist is extending through the late downswing BEFORE impact. Phil Cheetham's graph shows that it is flexing in the late downswing and that it only starts to extend just milliseconds before impact. He is also wrong to claim that I am comparing 2D images at SLOWER frame rates than a 3D system, which captures data points at 250-400fps. I am using images captured with a Phantom camera at frame rates of 8,200 frames/second - as shown in the next series of capture images from the following Phantom camera video. John Oda's hand motion through impact. One can clearly see that his left wrist is not extending rapidly through impact. Dan Carraher has also totally misinterpreted the 2nd graph. Any graph point above the zero line represents flexion. So, the left wrist is becoming flexed during the late downswing starting at 0.625 seconds prior to impact and it is about 30 degrees flexed at impact. The right wrist is becoming less extended during the late downswing, but it is still slightly extended (10 degrees extended) at impact. Jeff.
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Post by dubiousgolfer on Jul 13, 2017 9:43:23 GMT -5
Many thanks for this . Yes I am getting frustrated with the debate and might just back off . But am I correct , that there is no 100% way of confirming 'extension/flexion/stability' through compression period? That until we have the measurement technology to determine what happens to the clubface and ball motion during that period , it is just one person's opinion over the other?
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Post by imperfectgolfer on Jul 13, 2017 10:03:42 GMT -5
Many thanks for this . Yes I am getting frustrated with the debate and might just back off . But am I correct , that there is no 100% way of confirming 'extension/flexion/stability' through compression period? That until we have the measurement technology to determine what happens to the clubface and ball motion during that period , it is just one person's opinion over the other? Why back off the debate? Simply post the John Oda video and capture images of John Oda's swing through impact and then also comment on Dan's incorrect interpretation of graph 2. Yes - there is no method of accurately measuring left wrist stability at impact. However, if a DHer has <5 degrees of left wrist extension happening between P7 and P7.2 then he is likely keeping the clubface as practically stable as is humanly possible. Jeff.
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Post by imperfectgolfer on Jul 13, 2017 10:28:52 GMT -5
I see that Dan wrote the following regarding the Cheetham and Sweeney graphs-: " No it isn't. Cheetams graph shows it extending rapidly to impact and then moving towards flexion post impact, due to force of collision. You're literally reading the graph backwards. It moving up is extension in both graphs with respect to left wrist." Dan is totally wrong about his interpretation of the two graphs. Why doesn't he actually read the study's methodology and their author's interpretative conclusion? Here is an unedited quote from the Sweeney paper-: " At the top of the backswing the players displayed an average left wrist position that was 27° (±8) extended and 9° (±15) radially deviated. The average right wrist position at the same point was 58° (±12) extended and 16° (±21) ulnar deviated." Now look again at this graph and you will see that 27 degrees of left wrist extension at the end-backswing position is below the zero point. Also, here is an unedited quote from under figure 2 -: " Figure 2: A representative trial showing both left and right wrist A) angle and B) angular velocity through the downswing (+ve angle represents wrist flexion & ulnar deviation)." Note that a positive angle (which is above the zero point) represents wrist flexion. The same "facts" apply to the Cheetham graph. Here is an unedited quote from Phil Cheetham's PhD dissertation paper-: " Referring to Figure 14 we see at the top of backswing the lead wrist/forearm is radially deviated, extended, and pronated. This can be seen from the graph because all three curves are negative at the top and the first direction referred to in the legend is positive. During the downswing, flexion begins first, then a little extra pronation, followed by ulnar deviation, then supination, and finally just before impact the wrist begins to extend. At impact the lead wrist/forearm is ulnar deviated, flexed, and supinated. We see this from the graph in Figure 14 because all three curves are positive at this point." Jeff.
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Post by imperfectgolfer on Jul 13, 2017 11:35:27 GMT -5
I note that Dan Carraher now concedes that he has misinterpreted the Sweeney study's graph, and he stated in that GolfWRX golf forum thread-: "Yea you're right I just glanced and looked at graph quickly. I made an assumption based on what I know is happening. Camera based systems have a big problem reading wrist angles."
He wrote that he made an assumption based on what he knows is happening. However, that's the difference between science-based "facts" and assumption-based (ideology-based) "alternative facts". Dan Carraher reminds me of the Trump administration and its partisan supporters who prefer to believe in "alternative facts" rather than "true facts".
He also stated that camera based systems have a big problem reading wrist angles - but his assumption that the left wrist is rapidly and massively extending in the late downswing and through impact is seemingly based on 3-D camera systems!
Jeff.
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Post by imperfectgolfer on Jul 13, 2017 11:55:07 GMT -5
glk posted the following graph in that GolfWRX thread-: He wrongly claims that it shows that the left wrist is extending before impact, when it is actually flexing in the late downswing. Regarding the momentary transition in the direction of extension that happens mere milliseconds before impact, Phil Cheetham has stated that the graph cannot reflect that "fact" accurately because his 3-D camera sytem operates at 250 fps, which means that it only samples one data point for every 4-8" of travel as the hands reach near impact. Here is an unedited quote from Phil Cheetham's personal communication with me-: " Impact on the AMM system is considered as the immediate sample before the club passes the club face position at address. So if the clubhead is traveling at say 108mph (the average for my pro database) then in 4.17 ms it will have traveled 7.98 inches. So the handle twist velocity is measured anywhere from 0 to about 8 inches before impact. Probably on average at about 4 inches before impact, or 1/2 a sample period". Phil Cheetham has agreed with me that his 3-D system cannot accurately measure any left wrist extension happening at (or near impact) because of its low sampling frequency. This swing video of John Oda's swing captured at 8,200 fps clearly shows that the left wrist is not extending rapidly and massively through impact. Jeff.
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Post by imperfectgolfer on Jul 13, 2017 15:35:47 GMT -5
Dan Carraher posted this 3-D graph of one his students, who is apparently a scratch golfer. The green graph (which is presumably the relevant flexion-extension graph) shows that the left wrist starts extending well before impact. However, is that golfer a DHer, where his clubshaft does not bypass his left arm at P7.2? That's the critically important question! Here again is a slow-mo video of John Oda's golf swing - captured at 4,000 fps. Here are capture images from that video. Image 2 shows that his clubhead is ~12" post-impact and in image 3 it is ~24" post-impact. Note that he still has a FLW and that the clubshaft has not bypassed his left arm (from an angular rotational perspective). Now, let's see if Dan Carraher will post similarly-positioned capture images of his student golfer to see whether his clubshaft has not bypassed his left arm at P7.2+. Jeff.
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Post by dubiousgolfer on Jul 13, 2017 18:38:26 GMT -5
To be honest , I don't know what Dan Carraher's graph represents as he doesn't make it clear what the X and Y axis represents. He has also inferred that he'd need permission from the golfers to publish any personal swing information so I doubt he will be in a position to publish similar high speed camera videos.
I think the forum readers (and others) will need to decide themselves on the facts being shown on the GOLFWRX thread, your website and this forum (if they have the inclination to learn more with an open mind). So far , I haven't seen any quality evidence put forward by Iteach and FWP to validate their own opinions.
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Post by imperfectgolfer on Jul 13, 2017 19:35:17 GMT -5
To be honest , I don't know what Dan Carraher's graph represents as he doesn't make it clear what the X and Y axis represents. He has also inferred that he'd need permission from the golfers to publish any personal swing information so I doubt he will be in a position to publish similar high speed camera videos. I think the forum readers (and others) will need to decide themselves on the facts being shown on the GOLFWRX thread, your website and this forum (if they have the inclination to learn more with an open mind). So far , I haven't seen any quality evidence put forward by Iteach and FWP to validate their own opinions. I presume that you are posting under the name "WildThing" in the GolfWRX thread. I personally think that you are not posing your questions with enough probing questioning. For example, Dan Carraher claims that you can have a clubshaft that doesn't bypass the left arm at P7.2 (or at P7.4) even though the left wrist is rapidly extending. However, he hasn't stated how much increased left wrist extending can exist if the clubshaft doesn't bypass the left arm between P7 and P7.4. So, for example, I have no doubt that Jordan Spieth's left wrist is becoming less bowed between P7 and P7.5 in the images that Dan Carraher posted of Jordan's Spieth's followthrough, but how much increased left wrist extending can there be between P7 and P7.5 if the clubshaft does not bypass the left arm at P7.5 in image 3 below. Also, you should post these capture images of John Oda and ask Dan Carraher how much increased left wrist extending can theoretically happen between impact (image 1) and P7.4 (image 3) if the clubshaft doesn't bypass the left arm. You should also demand that he provide scientific "evidence" to support any claim that he makes with respect to your question. Jeff.
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Post by imperfectgolfer on Jul 13, 2017 22:38:34 GMT -5
It is astonishing to read the many wrongheaded comments made in that GolfWRX thread where a number of commentators state that ALL pro golfers are extending their left wrist between P6 and P7. That wrongheaded claim ignores the results of the Phil Cheetham study of 94 pro golfers, which showed that many of them were increasing their degree of left wrist flexion between P6 and impact. So, the question becomes - why is there such a discrepancy in different 3-D studies? I think that the answer is simple! Golfers who use a handle-dragging technique (as recommended by TGM literalists who believe that a golfer must "sustain lag" all the way into impact) will more likely have increased left wrist flexion happening between P6 and impact. By contrast, golfers who use a TGM swinging technique (based on the sequential release of PA#4 => PA#2) while simultaneously trying to maintain an intact LAFW will more likely have their maximum degree of left wrist flexion happening between P5.5 and P6.2 as they "turn the corner" and then they may have their left wrist increasingly extending between P6 and P7.5. However, the degree that the left wrist extends between P7 and P7.2 depends on how efficiently they can match the forward angular velocity of their left arm relative to the forward angular velocity of the clubshaft (which has acquired a certain finite magnitude of angular velocity by impact due to the sequential release of PA#4 => PA#2). Golfers who can better match the forward angular velocity of their left arm relative to the forward angular velocity of the clubshaft will likely have very little "left wrist extending" (< 5 degrees) happening between P7 and P7.2 and therefore their clubshaft will not bypass their left arm and they will be DHers. By contrast, golfers who stall their left arm's forward motion between P7 and P7.2 will more likely have a greater degree of "left wrist extending" happening between P7 and P7.2 and their clubshaft will bypass their left arm (signifying a left wrist flipping phenomenon) and they will be non-DHers. Dan Carraher wrongly believes that my definition of a DHer implies that there is ZERO "left wrist extending" happening between P7 and P7.2, which only demonstrates that he has never understood my drive-hold hand release action concept. Golfers, like Jordan Spieth who have a bowed left wrist at impact, can actually have a much greater degree of left wrist extension happening between P7 and P7.2 and still be classified as a DHer (because their clubshaft doesn't bypass their left arm by P7.2) simply due to the fact that they start off with a palmar flexed left wrist at P7. My definition of a DH hand release action is not based on any absolute magnitude of "left wrist extending" happening between P7 and P7.2 and it is only a comparative concept that implies that the clubface is more likely to have a lower ROC between P7 and P7.2 if the degree of "left wrist extending" and any associated left wrist circumduction is minimised.
In this explanation, I am ignoring another cause of the clubshaft bypassing the left arm between P7 and P7.2 secondary to left forearm supination - but that is another separate issue.
Jeff.
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