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Post by dubiousgolfer on Sept 20, 2017 20:16:22 GMT -5
Dr Mann I have been reading through swing modelling in Dave Tutelmans website below. www.tutelman.com/golf/swing/models4.phpHe presented a graph of work done at the joints by 4 test golfers during 'Nesbit/Serrano/Others' study (as below) He then went on to mention the following: ------------------------------- "This bar chart seems to contradict MacKenzie's results -- that a significant amount of clubhead speed comes from left shoulder torque. (And, in so doing, it would contradict my general assertion that later models didn't contradict earlier models; they just refined them and addressed questions the earlier models did not.) But it needn't be a contradiction. We did discuss (and MacKenzie himself mentioned) the possibility of right arm extension adding to left shoulder torque. Nesbit and Serrano's results say that two thirds or more of MacKenzie's "left shoulder torque" is actually due to right arm extension. It also suggests that all swings contain more "C-Motion" (used to be called "Leecommotion") than you might think." --------------------------------- Looking at the bar graph above , it does seem coincidental that all 4 subjects used the right shoulder a bit more than their left shoulder . Further there seems to be a fair amount of work being done with the right elbow (right arm extension). Doesn't this seem to suggest that all 4 golfers were exhibiting a 'right arm swinging' action with an 'active pivot' . I am guessing that they were using an active pivot because of the high work readings shown for right and left hip, lumbar and thoracic (or is this a wrong assumption?). In your opinion , what would the bar graph typically look like for a left arm swinging action using an active pivot? Wouldn't there be a lot less work being done by the right elbow?
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Post by imperfectgolfer on Sept 24, 2017 10:51:47 GMT -5
Dr Mann I have been reading through swing modelling in Dave Tutelmans website below. www.tutelman.com/golf/swing/models4.phpHe presented a graph of work done at the joints by 4 test golfers during 'Nesbit/Serrano/Others' study (as below) He then went on to mention the following: ------------------------------- "This bar chart seems to contradict MacKenzie's results -- that a significant amount of clubhead speed comes from left shoulder torque. (And, in so doing, it would contradict my general assertion that later models didn't contradict earlier models; they just refined them and addressed questions the earlier models did not.) But it needn't be a contradiction. We did discuss (and MacKenzie himself mentioned) the possibility of right arm extension adding to left shoulder torque. Nesbit and Serrano's results say that two thirds or more of MacKenzie's "left shoulder torque" is actually due to right arm extension. It also suggests that all swings contain more "C-Motion" (used to be called "Leecommotion") than you might think." --------------------------------- Looking at the bar graph above , it does seem coincidental that all 4 subjects used the right shoulder a bit more than their left shoulder . Further there seems to be a fair amount of work being done with the right elbow (right arm extension). Doesn't this seem to suggest that all 4 golfers were exhibiting a 'right arm swinging' action with an 'active pivot' . I am guessing that they were using an active pivot because of the high work readings shown for right and left hip, lumbar and thoracic (or is this a wrong assumption?). In your opinion , what would the bar graph typically look like for a left arm swinging action using an active pivot? Wouldn't there be a lot less work being done by the right elbow? I have taken a long time to respond to this post because I couldn’t easily motivate myself to spend time/effort to write about a junk research paper that has no practical value in helping golfers understand the biomechanics/mechanics of the golf swing. Nesbit’s paper has many flaws that make it of no practical value in helping a golfer better understand how to perform a golf swing. First of all, it is based on inverse dynamics where he attempts to calculate the forces/torques needed to create motion at the level of 15 ellipsoid-shaped joint areas joined together by spherical joints using a computer model. That computer model is not applicable to a “real life” golfer because it separates the pelvis from the lumbar spine and it presumes that there is independent work motion happening at the level of the lumbar spine that is independent of active work motion of the pelvis – which I have never seen happen in a pro golfer. I think that if a golfer has hula-hula flexibility that allows for torso-pelvic separation, that the pelvis and lower-mid lumbar spine moves as a single biomechanical unit (relative to the upper torso). So, when he states that most of the pivot torque is produced by the lumbar spine, I think that it is mainly being produced by muscles used to actively cause pelvic rotation. I think that it is nonsensical to believe that the lumbar spine area of the body is joined to the pelvis via a spherical joint zone that allows for rotary torques to be applied across that spherical joint zone. Then he claims that swing power is produced by the hips (seemingly independent of the pelvic/lumbar spine rotation) with the right hip producing most of the power. I think that it may apply to amateur golfers (as used in his small study) who likely use a right hip spinning motion, but I don’t think that it applies to many pro golfers who use the pro golfer’s pattern of inducing pelvic rotation during the early downswing (where contraction of the right-sided lateral pelvic rotator muscles cause a pelvic rotation away from a weight-pressure loaded right leg/foot). I think that any observed rotary motion of the right side of the pelvis is likely passive in many pro golfers who do not use their right gluteus maximus muscle to cause a right hip spinning motion. Also, Nesbit is seemingly TGM-illiterate and he does not understand the difference between a TGM swinging action (lead arm swinging action) due to a pivot-induced release of PA#4 compared to a right arm swinging action due to the sequential release of PA#5 => PA#1. We have no idea whether his amateur golfers use a TGM swinging action, a right arm swinging action, a TGM hitting action or even whether their pivot is active versus reactive. It is very obvious that his theoretical calculations are not taking these swing pattern variations into account. Nesbit claims that the left elbow can produce swing power (work) but I think that’s impossible in a TGM swinging action where a golfer keeps the left arm fully straight (like Adam Scott and Lexi Thompson) throughout the entire downswing and early followthrough. His theoretical estimations of work produced by the right elbow doesn’t take into account the TGM swinging technique used by a pro golfer. For example, it is possible to perform a flawless TGM swinging action with the left arm alone (as demonstrated by Jim George in my video project). Then, if a right arm straightening action is actively used between P5.5 and P7, it is only active to a small/limited degree (in order to syngergistically help in the smooth release of PA#3 and to help mechanically stabilize the lead wrist if the golfer uses a DH-hand release action through impact). That swing scenario is very different to the active right arm straightening action causing the release of PA#1 in a golfer who is a right arm swinger (or a TGM hitter) where it is performing much more work from a swing power perspective. Nesbit’s bar graphs involving the right elbow are much more compatible with a right arm swinging action (or a swing-hitting pattern) than the TGM/left arm swinging action used by pro golfers. Nesbit’s graphs show low work values for work produced at the level of the left shoulder socket, which therefore cannot be representative of golfers who use the Leslie King methodology of swinging the left arm actively using the left shoulder girdle muscles while allowing the pivot to react to the swinging motion of the left arm. That’s the swing technique that I personally use most of the time (as an alternative to a right arm swinging technique) and my pivot action is reactive (passive), and not active. You quoted David Tutelman as follows-: “ This bar chart seems to contradict MacKenzie's results -- that a significant amount of clubhead speed comes from left shoulder torque. (And, in so doing, it would contradict my general assertion that later models didn't contradict earlier models; they just refined them and addressed questions the earlier models did not.) But it needn't be a contradiction. We did discuss (and MacKenzie himself mentioned) the possibility of right arm extension adding to left shoulder torque. Nesbit and Serrano's results say that two thirds or more of MacKenzie's "left shoulder torque" is actually due to right arm extension. It also suggests that all swings contain more "C-Motion" (used to be called "Leecommotion") than you might think.” I personally think that David Tutelman’s “belief” that the right arm straightening action is 66+%” responsible for the swing power needed to release PA#4 may apply to swing hitters (like the amateurish, high handicap golfers used in Nesbit’s study), but I don’t believe that it applies to PGA tour golfers who actively use their pivot motion (and left shoulder girdle muscles) to release PA#4. I have no idea why any golfer would even be interested in learning about the amount of work being performed by different body parts if they want to learn how to perform a golf swing like a PGA tour golfer. What they really need to learn is the underlying biomechanics and how to efficiently perform a kinematic sequence in an optimum manner. Who cares how much work is performed (as measured in N.m) during a full golf swing action? Jeff.
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Post by dubiousgolfer on Sept 28, 2017 3:18:25 GMT -5
Dr Mann - Many thanks for taking the time to reply back in such detail.
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