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Post by tomdavis76 on Sept 5, 2013 20:05:20 GMT -5
Cray- They know how to measure using their system, and they have measured (and, as a result, recognize) the movements involved in the second fire. Beyond that, they don't know much about the golf swing! Jaffaray- they are not teachers and don't pretend to be like some others do. Also pure rotation and translation and rotation combined are 2 different things, now you know! Cray- We knew that and Kel, in fact, pointed that aspect of the second fire out to the biomechanists on Facebook. Clay forgot to tell you that. That's why he posted this video for them:
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Post by chipitin on Sept 5, 2013 20:12:50 GMT -5
Jaffaray- they are not teachers and don't pretend to be like some others do. Also pure rotation and translation and rotation combined are 2 different things, now you know! Cray- We knew that and Kel, in fact, pointed that aspect of the second fire out to the biomechanists on Facebook. Clay forgot to tell you that. That's why he posted this video for them: ;D
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Post by chipitin on Sept 5, 2013 20:13:40 GMT -5
It's in the details Jaffray the details.
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Post by tomdavis76 on Sept 5, 2013 20:32:40 GMT -5
Just so we have the sequence of events straight...
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Post by imperfectgolfer on Sept 5, 2013 20:46:58 GMT -5
I have deleted a number of Jeffy's and Chipitin's posts because they are simply trading in ad hominem insults. As Global Moderator, I will not tolerate that type of posting-behavior in this forum. When I get tired of selectively deleting a certain number of their posts, then I will simply delete all their posts, so that they will become "functionally" banned from this forum.
Jeff.
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Post by imperfectgolfer on Sept 5, 2013 20:57:37 GMT -5
Chipitin noted that I harbor different opinions regarding certain aspects of golf biomechanics than KM/Jeffy. Jeffy then stated-: "Quite different"? Please elaborate. His critiques are quite modest relative to the broad scope of Kelvin's published work and, for the most part, reflect his desire to find fault in others to provoke "discussion" so he has others to play with.
Jeffy may perceive my critiques to be modest in quality/quantity, but I think that they reflect a very different way of thinking about golf swing biomechanics. I actually disagree with the majority of KM's opinions re: golf swing biomechanics (as they are expressed in his many articles), but I don't have the time or interest to criticize all of them in this forum, because it would take far too much time and it would also be very labor-intensive.
Jeffy may think of KM as having a great insight into the world of golf swing biomechanics, but I think that his knowledge regarding golf swing biomechanics/mechanics is very limited and roughly equivalent to golf instructors who he frequently insults (eg, David Leadbetter). His chief speciality is describing micro-moves of a selective number of golfers (who he arbitrarily labels elite golfers), but those micro-moves are minor biomechanical elements that have very little effect on a golfer's fundamental golf swing technique. I think that KM/Jeffy have a huge knowledge gap when it comes to understanding that golfers can be swingers (left arm or right arm), or hitters, or switters - and that's the arena where different critical swing fundamentals reside.
Jeff.
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Post by tomdavis76 on Sept 5, 2013 21:58:13 GMT -5
IMO, "swingers, hitters and switters" are pure fantasy land. Please show me why I am wrong!
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Post by imperfectgolfer on Sept 6, 2013 1:35:40 GMT -5
Jeffy wrote-: "IMO, "swingers, hitters and switters" are pure fantasy land. Please show me why I am wrong!"
How can I show that Jeffy is wrong if he is not willing to learn how to try and perform a variety of swing techniques - i) left arm swinging with an active pivot action; ii) left arm swinging with a reactive pivot action; iii) right arm swinging, iv) right arm hitting and v) switting (where right arm straightening in the late downswing applies push-pressure to PP#3 and not PP#1)? Jeffy may be expecting me to present research evidence, but I know of no researcher who is measuring push-pressure (applied by the right arm) at PP#1 and PP#3 during a golfer's swing action. That's why "insight" is primarily gained by experimenting - after first mentally understanding the many differences in fundamentals between a swinging versus a hitting technique.
Jeff.
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Post by richie3jack on Sept 6, 2013 7:53:28 GMT -5
I have deleted a number of Jeffy's and Chipitin's posts because they are simply trading in ad hominem insults. As Global Moderator, I will not tolerate that type of posting-behavior in this forum. When I get tired of selectively deleting a certain number of their posts, then I will simply delete all their posts, so that they will become "functionally" banned from this forum. Jeff. And...good luck with that 3JACK
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Post by imperfectgolfer on Sept 6, 2013 10:33:48 GMT -5
See this Jeffy forum thread where KM and MD are presenting their opinions. jeffygolf.com/showthread.php?787-Questions-for-DuffeyMike Duffey wrote regarding the concept of a second acceleration of the shoulders (actually upper torso).-: " I believe that model shows that the second acceleration *can* happen, but not necessarily that it should happen. It is very likely caused by the the arms and club. Again, typically in that model with a good swing, the arms and club reach peak velocity after the torso. They have enough mass and velocity that slowing them down will act to speed the torso back up.". If any forum member can explain how slowing of the arms/club post-impact can speed up the rotation of the shoulders (upper torso) creating a second peak velocity for the shoulder rotation, then I would like to analyze their reasoning. First of all, what would cause the arms/club to slow down after impact? It is my experience that many pro golfers complete their finish action to such a high degree that the club wraps around their back at their finish position, and there is no slowing of the club or shoulder rotation post-impact. Do you see any slowing down of the arm/club or shoulder motion in Gary Woodland's post impact time period? If the club does slow down after impact in a full golf swing, then I presume that the golfer is intentionally aborting his followthrough/finish action, and that requires a deliberate slowing down of the arm motion. When I examine their aborted followthrough swing actions, I always notice that the shoulder motion slows down proportionately so that the arms are still reasonably closely aligned relative to the front of the chest wall. Have you ever see a professional golfer use an aborted followthrough swing action where the shoulders actually speed up and get way in front of the arms (from a rotational perspective)? Another point is that MD seemingly has a swing model-in-mind where the energy used to move the arms/club comes entirely from the rotation of the torso. However, I believe that the energy used to move the arms is also derived from the shoulder girdle muscles that move the arms independently within their respective shoulder sockets while the upper torso is rotating. That independent biomechanical phenomenon allows the left arm to mainly move downwards between P4 and P7 and that biomechanical phenomenon requires active depression of the left arm combined with abduction of the left arm (relative to the end-backswing position where the left arm is elevated far above its address position and where the left arm is adducted across the front of the upper torso). This biomechanical phenomenon represents the release of PA#4 and the energy needed to depress/abduct the left arm away from its P4 location to its impact location is unrelated to the energy used to rotate the upper torso. The upper torso rotation (around the bent-over spine axis) and left arm motion (down a totally different axis of motion) must obviously be synchronously coordinated so that the upper torso-left arm relationship at impact is optimized, but that doesn't mean that the energy used to depress/abduct the left arm is entirely derived from the energy used to rotate the upper torso (shoulders). Jeff.
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Post by imperfectgolfer on Sept 6, 2013 10:56:28 GMT -5
MD also stated in that Jeffy-forum thread when answering this KM question ( Mr Kwon stated that there’s this” single bout” of leg/pelvis fire on the downswing. What is it supposed to do the rest of the swing?)-: "Kwon is, I believe, is specifically referring to rotation about the vertical or long axis of the pelvis. His presumption is that the muscles that work primarily to rotate the pelvis fire to create that rotation and continue to do so until they stop later in the swing. This is as opposed to activating to start that motion, shutting off to intentionally slow that rotation, then ramping back up the muscle activation to reaccelerate that rotation. Depending on swing style, I expect that most of the intentional slowing of the pelvis will happen after impact."
What does he mean by "intentional slowing down of the pelvis post-impact". Why would a pro golfer want to intentionally slow down his pelvic motion after impact in a full golf swing?
Consider Gary Woodland's swing action.
Pay particular attention to the motion of his right thigh and right hip joint area after impact. I don't see it slowing down after impact. In fact, I think that it may speed up after impact. What is the source of the energy that is required to continue to move the right pelvis after impact so that the pelvis becomes square to the target at the finish position? It is my opinion that the "energy" is mainly derived from the active mid-upper torso rotation that continues after impact, and partly from the continued counterclockwise rotation of the left thigh and associated left hip joint area. Note that GW's upper torso (shoulders) is rotating very fast after impact and it is bypassing the lower body/pelvis. As this happens, "forces" must surely be transmitted down the spine and torso muscles/ligaments from the upper torso down to the lower torso to help the pelvis become square to the target at the finish position. Also, note that the right hip joint area/right lower limb becomes progressively more unweighted between P7 and P9+, and that decreases the amount of energy needed to change the directional orientation of the right pelvis from its impact orientation to its finish orientation.
Jeff.
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Post by imperfectgolfer on Sept 6, 2013 11:59:02 GMT -5
Consider how MD responded to another question posed by KM relating to the position of the pelvic sacrum during the downswing action-: " I’m asking if it should rotate in one place. Then I'll go with my initial answer. To stay in on exact position, it would have to be the perfect center of rotation for the entire swing." How can the sacrum ever be conceived to the perfect center of rotation of the entire swing? There is no such phenomenon as rotation of the pelvis around a central axis of rotation. The pelvis simply moves in space because the two femoral heads apply a force to their associated acetabular sockets that consequently moves the pelvis. Here are capture images showing the positional motion of Jack Nicklaus' sacrum during his downswing action. I have drawn a blue line over his sacrum at the P4 position - image 2. I have drawn a yellow line over his sacrum at the P5 position - image 3, and I have drawn a green line over his sacrum at the P6+ position - image 4. It is obvious that the sacrum is moving in space - both from a rotational and linear/translational perspective. The rotational component makes the sacrum move away from the target while the linear component (due to any sliding of the left thigh/left pelvis in a targetwards direction) causes the sacrum to move towards the target. The end-result of these two biomechanical phenomena is individual golfer-dependent, and it depends on how much the pelvis slides targetwards while the pelvis is simultaneously rotating counterclockwise secondary to the "left hip clearing action ala Hogan" phenomenon. Jeff.
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Post by chipitin on Sept 6, 2013 12:03:28 GMT -5
effy is confused about what Kelvin said concerning the second fire because its more than just the legs: www.aroundhawaii.com/lifestyle/health_and_fitness/2008-12-tiger-and-sadlowski-swing-emergence-of-a-new-more-powerful-swing.html"The other two moves are vertical jump and rotational twist. So I call it a jump/twist move. The analogy would be like an ice skater doing the preparation for a triple jump. They would lower their body, counter-rotate slightly, then jump and twist, except we won't leave the ground. In order to get the most from your body, these two moves are essential. move your entire weight vertically up and rotate in order to complete the MFT swing. The second firing needs to be really explosive and it needs to drive you through the last 90 degrees of hip rotation till the end of the swing. In a biomechanical graph, this means that Tiger has two velocity peaks for his hips and shoulders. His second hip velocity peak occurs just prior to impact and this "slingshots" his shoulders (2nd firing) into the ball with maximum force. Ben Hogan did this as well. But Jamie's swing is even more violent and powerful. His hips and shoulders reach their 2nd velocity peaks right at impact. All of this adds to his speed AND effective mass at impact. The added mass of his body firing at high speed right at impact will add to his smash factor and higher ball speeds at impact. This is sledgehammering at its finest." The problem is that Jamie S.'s sequence graph, which shows pelvic rotation separate from translation, demonstrates Kelvin is dead wrong about a "second fire" or peak acceleration of the pelvis and he doesn't understand that translation is more than just movement left/right, it also is up/down and backwards and forwards!!! Translation and rotation happen together, but you have to be able to separate them if you're going to use the words correctly. Kelvin has created a brand new world where rotation is more than just movement around an axis. Why? BECAUSE ALL HE SEES ON VIDEO IS ROTATION AND TRANSLATION MERGED TOGETHER. If Kelvin admits there's a difference between translation and rotation then his articles are incorrect. That's why he never did it on facebook or admit on your site there's a difference. Kelvin claims the biomechanists use a "narrow" definition of rotation. They don't use a narrow defintion of rotation. They used the word exactly as it is used and has always been used. Kelvin is the one creating new definitions and the fact that he never properly understood translation (or that AMM wasn't K-Vest) and rotation is his fundamental error in his peak acceleration theory.
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Post by chipitin on Sept 6, 2013 12:05:26 GMT -5
There aren't any "shoulder" readings on AMM's graph. Only thorax, another big difference that Kelvin misses.
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Post by chipitin on Sept 6, 2013 12:06:54 GMT -5
AMM's rotation is based upon the local axis of the pelvis! That's why digitization is so important and since Kelvin has never used AMM or seen it in action, he incorrectly assumed it was like K-Vest where the location of the sensor can change the readings!!! Bad assumptions = Bad conclusions.
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