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Post by imperfectgolfer on Jan 17, 2013 12:05:03 GMT -5
Here is a link to the 33 minute video where BM and MJ discuss the 3-D machine. vimeo.com/57574107BM spent the first 2 minute discussing the JS graphs. I found his explanation incoherent. He stated that the TPI kinematic graphs show the pelvis decelerating because the pelvis is becoming more open. Why should that produce deceleration? He didn't provide an answer. He even implied that one needs a PhD in biomechanics to answer that question. I still have not read an explanation as to why the pelvic angle graph, which is sloping upwards continuously throughout the downswing, becomes so bell-shaped when presented as a pelvic velocity graph. Is that pelvic deceleration seen in the pelvic velocity graph "real" and actually reflective of reality (in terms of the "real" degree of deceleration)? The second point is that MJ/BM state that pelvic rotational speed is maximum at P5. That "belief" is not new to me. Here is my hand-drawn graph - based on the TPI graph - which I produced many years ago. I superimposed images of Badds to show when the pelvic peak velocity occurs - note that I have him at the P5 position. I still believe that this is correct because I think of the speed of the "left hip clearing action" as being reflective of pelvic rotational speed, and I think that one can pull the left hip joint back towards the tush line at the start of the downswing very fast because the left leg is basically unweighted. By P5, the hips are square, and from then on one is progressively weighting the left leg. I believe that as one straightens/braces/"weights" the left leg that it will naturally impede the speed of motion of the "left hip clearing action". The second major factor that slows the pelvis is speeding up of the upper torso rotation, which causes the pelvis to slow down. I like Cheetham's explanation, which is available in this pdf document. www.advancedmotionmeasurement.com/Portals/0/articles/Simple%20Model%20of%20Pelvis-Thorax%20Kinematic%20Sequence.pdfIn that model, he has the pelvis and thorax rotating together at the start of the downswing (which fits in with the spine engine concept) where the power comes from the pelvis, and not the thorax. I disagree with that aspect of the model because I believe that a golfer can keep the thorax back at the start of the downswing and create a state of dynamic torso-pelvic separation - like Bubba Watson. That is why I hand-drew my diagram differently, and I created a time-gap between the start of the pelvic rotation and the start of the thorax rotation. I believe that are no "gold standard" rules in this area - one can have no, some, or a lot of torso-pelvic separation at the start of the downswing. Note that I didn't place a time scale on my X axis and I didn't specifically indicate when the pelvis and thorax should decelerate in the downswing. This was a deliberate choice because I believe that their are no "gold standard" rules that mandate a specific pattern for any individual golfer. MJ seemingly has become enamored of the K-vest as a teaching device, but I know of no evidence that it produces better golf improvement results than alternative teaching approaches. I think that one can visually see (using slow motion video) if there are gross errors in pelvic and thorax motion in an individual golfer, and I still have never come across any "evidence" that a 3-D device (especially a primitive device like the K vest) can provide useful information re: golf swing biomechanics/mechanics that is not obtainable by slow motion video. Did you find the BM/MJ video presentation useful? Did you learn anything new? Jeff.
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Post by gmbtempe on Jan 17, 2013 14:17:42 GMT -5
I dont have the time right now to watch 33 min of video but I have an opinion regarding this statement:
I believe that as one straightens/braces/"weights" the left leg that it will naturally impede the speed of motion of the "left hip clearing action".
This has been my issue with SnT or those related. If the weight is too far left then you need a lot of athletic ability in order to get the pelvis to move fast enough to clear your hips properly.
You still make solid contact but the plane line is well out to the right and the face is delofted, and for me that produced a lot of hooks and loss of distance.
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Post by tomdavis76 on Jan 17, 2013 20:43:38 GMT -5
I dont have the time right now to watch 33 min of video but I have an opinion regarding this statement: I believe that as one straightens/braces/"weights" the left leg that it will naturally impede the speed of motion of the "left hip clearing action".
This has been my issue with SnT or those related. If the weight is too far left then you need a lot of athletic ability in order to get the pelvis to move fast enough to clear your hips properly. You still make solid contact but the plane line is well out to the right and the face is delofted, and for me that produced a lot of hooks and loss of distance. I also agree with that. It fits in perfectly with the weight back on the ball of the right foot and left foot float/rotating through impact we see in some of the bombers. It's now standard fare for Kelvin.
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Post by tomdavis76 on Jan 17, 2013 20:53:09 GMT -5
Here is a link to the 33 minute video where BM and MJ discuss the 3-D machine. vimeo.com/57574107BM spent the first 2 minute discussing the JS graphs. I found his explanation incoherent. He stated that the TPI kinematic graphs show the pelvis decelerating because the pelvis is becoming more open. Why should that produce deceleration? He didn't provide an answer. He even implied that one needs a PhD in biomechanics to answer that question. I still have not read an explanation as to why the pelvic angle graph, which is sloping upwards continuously throughout the downswing, becomes so bell-shaped when presented as a pelvic velocity graph. Is that pelvic deceleration seen in the pelvic velocity graph "real" and actually reflective of reality (in terms of the "real" degree of deceleration)?
The second point is that MJ/BM state that pelvic rotational speed is maximum at P5. That "belief" is not new to me. Here is my hand-drawn graph - based on the TPI graph - which I produced many years ago. I superimposed images of Badds to show when the pelvic peak velocity occurs - note that I have him at the P5 position. I still believe that this is correct because I think of the speed of the "left hip clearing action" as being reflective of pelvic rotational speed, and I think that one can pull the left hip joint back towards the tush line at the start of the downswing very fast because the left leg is basically unweighted. By P5, the hips are square, and from then on one is progressively weighting the left leg. I believe that as one straightens/braces/"weights" the left leg that it will naturally impede the speed of motion of the "left hip clearing action". The second major factor that slows the pelvis is speeding up of the upper torso rotation, which causes the pelvis to slow down. I like Cheetham's explanation, which is available in this pdf document. www.advancedmotionmeasurement.com/Portals/0/articles/Simple%20Model%20of%20Pelvis-Thorax%20Kinematic%20Sequence.pdfIn that model, he has the pelvis and thorax rotating together at the start of the downswing (which fits in with the spine engine concept) where the power comes from the pelvis, and not the thorax. I disagree with that aspect of the model because I believe that a golfer can keep the thorax back at the start of the downswing and create a state of dynamic torso-pelvic separation - like Bubba Watson. That is why I hand-drew my diagram differently, and I created a time-gap between the start of the pelvic rotation and the start of the thorax rotation. I believe that are no "gold standard" rules in this area - one can have no, some, or a lot of torso-pelvic separation at the start of the downswing. Note that I didn't place a time scale on my X axis and I didn't specifically indicate when the pelvis and thorax should decelerate in the downswing. This was a deliberate choice because I believe that their are no "gold standard" rules that mandate a specific pattern for any individual golfer. MJ seemingly has become enamored of the K-vest as a teaching device, but I know of no evidence that it produces better golf improvement results than alternative teaching approaches. I think that one can visually see (using slow motion video) if there are gross errors in pelvic and thorax motion in an individual golfer, and I still have never come across any "evidence" that a 3-D device (especially a primitive device like the K vest) can provide useful information re: golf swing biomechanics/mechanics that is not obtainable by slow motion video. Did you find the BM/MJ video presentation useful? Did you learn anything new? Jeff. That's just the math. The slope changes in the pelvis angles graph are subtle, but that's what is created once its differentiated. I was actually more surprised by the shape of the thorax rotational velocity graph. Do the AMM3D graphs reflect reality? Well, they reflect what the sensors were doing! But the sensors can shift during the swing, a big reason why K vest is junk. Tapio has outlined other technical issues with sensor based systems. As far as I know, the "best" way to gather biomechainical movement of the spine, hips, etc. through a sensor based system is to embed sensors in the vertebrae, the pelvic bone (whatever that's called), etc. (even the skin can shift during movement). Horses will put up with that, but not many tour players.
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Post by imperfectgolfer on Jan 17, 2013 21:39:06 GMT -5
Jeffy wrote-: " It fits in perfectly with the weight back on the ball of the right foot and left foot float/rotating through impact we see in some of the bombers."
I would never recommend weight back on the right forefoot at impact - as seen in those two golfers. I much prefer to see a grounded left foot as seen in Dominic Mazza's traditional golf swing action, and he can hit 400 yard drives without float-rotating the left foot.
Note how stable his left foot is through impact. Also, note that his right foot becomes unweighted by impact and he drags his right foot forward during his followthrough.
I think that Dominic Mazza's swing action is much more stable than Geoff Olahan's swing action. GO not only float-spins his left foot through impact, but he also pulls his left foot back (away from the target) and then replants it on the ground about 6" further away from the target. I don't like that type of unstable lead foot action through impact. I also don't think that it necessarily increases clubhead speed (Dominic Mazza has an equivalent clubhead speed using a stable, grounded left foot technique), although it obviously allows the pelvis to rotate more freely through impact.
Jeff.
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Post by tomdavis76 on Jan 17, 2013 22:28:33 GMT -5
Jeffy wrote-: " It fits in perfectly with the weight back on the ball of the right foot and left foot float/rotating through impact we see in some of the bombers." I would never recommend weight back on the right forefoot at impact - as seen in those two golfers. I much prefer to see a grounded left foot as seen in Dominic Mazza's traditional golf swing action, and he can hit 400 yard drives without float-rotating the left foot. Note how stable his left foot is through impact. Also, note that his right foot becomes unweighted by impact and he drags his right foot forward during his followthrough. I think that Dominic Mazza's swing action is much more stable than Geoff Olahan's swing action. GO not only float-spins his left foot through impact, but he also pulls his left foot back (away from the target) and then replants it on the ground about 6" further away from the target. I don't like that type of unstable lead foot action through impact. I also don't think that it necessarily increases clubhead speed (Dominic Mazza has an equivalent clubhead speed using a stable, grounded left foot technique), although it obviously allows the pelvis to rotate more freely through impact. Jeff. Tiger did it... www.youtube.com/watchfeature=player_embedded&v=alfdujXMW8s
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Post by imperfectgolfer on Jan 17, 2013 23:58:50 GMT -5
Tiger may have done it in that swing, but that was a poor swing where he looked out-of-control - snapping his left leg too straight and allowing his left foot to rotate against the ground.
I much prefer Tiger's swing when he doesn't try to swing too hard - as seen in his Nike commercial sequences.
I think that KM and you are fixated too much on distance at the expense of stability and accuracy. I favor stability and control and accuracy over the idea of trying to get a few more yards of distance.
Ben Hogan is my role model - look at his stable left foot through impact, despite tremendous rotation of his lower-mid torso through impact.
George Knudson is another good role model.
Jeff.
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Post by imperfectgolfer on Jan 18, 2013 11:35:42 GMT -5
BM has produced a shorter 7 minute version of his video. vimeo.com/57631397In this video, he is promoting a pivot motion where the upper body must automatically/naturally slow down the pelvis rotation in the late downswing (BM uses the Cheetham sitting-in-a-chair explanation) when the upper body and arms swing faster through the impact zone. That phenomenon applies to golfers who use a combined "CF-arm release action + full-roll hand release action". However, there is another subset of golfers who use a combined "CP-arm release action + no-roll hand release action" through impact and I believe that they must continue to actively rotate their lower-mid torso through impact in order to to optimally perform their combined "CP-arm release action + no-roll hand release action". Ben Hogan is the prototypical golfer who uses this technique - as exemplified by this video. Here are capture images from this video. Ben Hogan is moving his lower-mid torso in the way that BM doesn't recommend - where the entire torso moves synchronously through impact and where there is no deceleration of the pelvic (lower body) motion secondary to a relative speeding up of the upper torso's rotation. BM may no longer have the requisite flexibility/mobility of the lower-mid torso to perform this type of swing action, but it is a viable option for young flexible golfers. In my impact chapter, I have described the biomechanics of both swing techniques, so that an individual golfer can experiment with each technique, and then decide which technique works best for him. Jeff.
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Post by tomdavis76 on Jan 18, 2013 18:34:14 GMT -5
Tiger may have done it in that swing, but that was a poor swing where he looked out-of-control - snapping his left leg too straight and allowing his left foot to rotate against the ground.I much prefer Tiger's swing when he doesn't try to swing too hard - as seen in his Nike commercial sequences. I think that KM and you are fixated too much on distance at the expense of stability and accuracy. I favor stability and control and accuracy over the idea of trying to get a few more yards of distance. Ben Hogan is my role model - look at his stable left foot through impact, despite tremendous rotation of his lower-mid torso through impact. George Knudson is another good role model. Jeff. I'm sure you'll agree that is simply your biased opinion; I think it was a very good controlled power swing with very little, if anything, to criticize.
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Post by imperfectgolfer on Jan 18, 2013 20:29:10 GMT -5
All my posts simply reflect my biased personal opinion, and I am very happy to posit my biased personal opinion as an alternative option to KM's/Jeffy's biased opinions, so that neutral/independent forum members can be exposed to two different/contrary opinions.
Jeff.
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Post by imperfectgolfer on Jan 18, 2013 22:55:47 GMT -5
KM, and Jeffy, think that Scott Stallings' swing is a good swing - when he pulls his left foot back about 6-12" through impact and ends up with an over-rotated pelvis (with the right anterior pelvis closer to the target than the left anterior pelvis).
Why would that represent an advantage - to over-rotate the pelvis in that manner?
Why is he pulling the heel of the left foot back, which means that his forward weight was on the toe of his left foot, rather than on the heel of his left foot - which should happen if one correctly uses David Lee's counterfall motion. Look at the upline view of George Knudson's swing - note how he apparently has his weight on his left heel through impact and not the left forefoot.
As KM states in his video presentation, there are different ways to get forward onto the lead foot in the downswing. I much prefer the way that Ben Hogan and George Knudson perform the action. I think that the pelvis should be square to the target at the I-finish position, and I don't think that the right anterior pelvis should be closer to the target than the left anterior pelvis.
Jeff.
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Post by tomdavis76 on Jan 19, 2013 11:47:20 GMT -5
KM, and Jeffy, think that Scott Stallings' swing is a good swing - when he pulls his left foot back about 6-12" through impact and ends up with an over-rotated pelvis (with the right anterior pelvis closer to the target than the left anterior pelvis). Why would that represent an advantage - to over-rotate the pelvis in that manner? Why is he pulling the heel of the left foot back, which means that his forward weight was on the toe of his left foot, rather than on the heel of his left foot - which should happen if one correctly uses David Lee's counterfall motion. Look at the upline view of George Knudson's swing - note how he apparently has his weight on his left heel through impact and not the left forefoot. As KM states in his video presentation, there are different ways to get forward onto the lead foot in the downswing. I much prefer the way that Ben Hogan and George Knudson perform the action. I think that the pelvis should be square to the target at the I-finish position, and I don't think that the right anterior pelvis should be closer to the target than the left anterior pelvis. Jeff. This is crux of it, Jeff. The weight stays back on the right. It would be fascinating to get some force plate data so it could be quantified, particularly that old Tiger swing and his current lean-left influenced swing (though, I don't see him leaning left that much if at all). Since the weight is more back toward the right foot, the player would wind up leaning away from the target very awkwardly if the left foot didn't pull back. The pull-back is required to maintain balance. "Over-rotated pelvis"? Now, there is a new "swing fault" to avoid...
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Post by imperfectgolfer on Jan 19, 2013 12:17:47 GMT -5
I have zero sympathy for the idea of leaning back and having weight on the right foot through impact - especially not for iron shots.
Most importantly, a golfer who pulls back the left foot through impact is in a state of dynamic imbalance, and I cannot fathom why any golfer would want to create a scenario where he may become dynamically unbalanced - especially when I cannot perceive any advantage to the floating-rotating left leg technique.
Jeff.
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Post by tomdavis76 on Jan 19, 2013 12:34:47 GMT -5
I have zero sympathy for the idea of leaning back and having weight on the right foot through impact - especially not for iron shots. Most importantly, a golfer who pulls back the left foot through impact is in a state of dynamic imbalance, and I cannot fathom why any golfer would want to create a scenario where he may become dynamically unbalanced - especially when I cannot perceive any advantage to the floating-rotating left leg technique. Jeff. Give it time; you don't always catch on right away...
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Post by imperfectgolfer on Jan 19, 2013 12:54:52 GMT -5
I think that piece of advice applies more to you than me, especially when it comes to your frequent propensity to come up with wild allegations (eg. your over-the-top allegation that Cheetham was flagrantly misrepresenting reality with his TPI graphs - an allegation which you eventually were forced to correct).
If you could present a rational argument that justifies the concept of having a floating/rotating left leg through impact, then you would have presented that argument by now. This situation reminds me of BM who asserted that massive pelvic deceleration was essential in a full golf swing - but he could never provide a coherent reason for adopting that position.
Jeff.
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