Post by imperfectgolfer on Dec 6, 2018 11:06:17 GMT -5
Let's consider Luke List's pelvic rotary action between P4 and P5.
Here are capture images from a you-tube video ( youtu.be/40aU9Xm3QWw ) where Sasho MacKenzie is analysing Luke List's COP (center-of-pressure) measurements during his downswing action.
Here are capture images from the video.
The COP readings are in a white font in that light-grey area, but they are difficult to see, so I have repeated the COP readings in a larger white font in the black area.
Image 1 is at his end-backswing (P4) position. Note that Luke List has 80% of his overall COP measurement under his right foot and 20% under his left foot.
Image 2 is when he starts his downswing's pelvic rotation. Note that he has 85% of his overall COP measurement under his right foot and 15% under his left foot.That means that he is actually increasingly weight-pressure loading his right foot as he starts the downswing's pelvic rotation.
Image 3 is fractionally later. Note that he still has 85% of his overall COP measurement under his right foot and 15% under his left foot. Note how much he has rotated his pelvis counterclockwise between image 1 and image 3.
Image 4 shows him reaching the end of his hip-squaring phase, which happens much earlier than P5 in his super-efficient pelvic rotary action. Note that he still has 76% of his overall COP measurement under the right foot and only 24% under the left foot.
I believe that Luke List is primarily using his right-sided lateral pelvic rotator muscles to rotate his pelvis counterclockwise between P4 and P5 and I think that he is super-efficient with respect to his ability to use his right-sided lateral pelvic rotator muscles to rotate his pelvis counterclockwise because he is "stabilising" his right leg/foot by maintaining a large degree of weight-pressure loading of his right leg/foot during his hip-squaring action. If he followed Tyler Ferrell's advice and quickly transferred his weight-pressure loading from the right foot => the left foot during the early downswing's P4 => P5 time period so that he already had 70% of his overall COP-measurement under his left foot, and only 30% of his overall COP-measurement remaining under his right foot, by the P5 position, then it is very likely that he could not use his right-sided lateral pelvic rotator muscles to rotate his pelvis counterclockwise with such great efficiency between P4 and P5.
If you believe that Dr.Kwon's theoretically-conceived Newtonian forces are causally responsible for rotating the pelvis counterclockwise during the hip squaring phase, then how can his theoretical model explain Luke List's counterclockwise pelvis rotation that happens between P4 and P4.5 if Luke List still has 76-85% of his overall COP measurement under his right foot during that hip-squaring phase time period, which means that he has only 15-24% of his overall COP measurement under his lead foot during the hip-squaring phase? Look at this video produced by Dr. Kwon - www.youtube.com/watch?v=fB2FQi1FyMg - and carefully watch what is happening between the 0.50 - 0.54 minute time point of the video. Note how the GRF moment produced by the right foot decreases between P4 and P4.5 while the GRF moment produced by the left foot dramatically increases. The moment arm also increases because the left foot's GRF moment is producing most of the GRF for the overall GRF moment (F), which surely necessitates that the theoretical golfer model must have most of his COP measurement under his lead foot during that hip-squaring time period. However, Luke List only has 15-24% of his overall COP measurment under his lead foot during his hip-squaring phase and I cannot understand how he could be generating the necessary GRF moment force that Dr.Kwon's theoretical model requires in order for it to induce a passive counterclockwise rotation of the pelvis that happens during the hip-squaring phase. Can you explain how it is possible!
Jeff.
Here are capture images from a you-tube video ( youtu.be/40aU9Xm3QWw ) where Sasho MacKenzie is analysing Luke List's COP (center-of-pressure) measurements during his downswing action.
Here are capture images from the video.
The COP readings are in a white font in that light-grey area, but they are difficult to see, so I have repeated the COP readings in a larger white font in the black area.
Image 1 is at his end-backswing (P4) position. Note that Luke List has 80% of his overall COP measurement under his right foot and 20% under his left foot.
Image 2 is when he starts his downswing's pelvic rotation. Note that he has 85% of his overall COP measurement under his right foot and 15% under his left foot.That means that he is actually increasingly weight-pressure loading his right foot as he starts the downswing's pelvic rotation.
Image 3 is fractionally later. Note that he still has 85% of his overall COP measurement under his right foot and 15% under his left foot. Note how much he has rotated his pelvis counterclockwise between image 1 and image 3.
Image 4 shows him reaching the end of his hip-squaring phase, which happens much earlier than P5 in his super-efficient pelvic rotary action. Note that he still has 76% of his overall COP measurement under the right foot and only 24% under the left foot.
I believe that Luke List is primarily using his right-sided lateral pelvic rotator muscles to rotate his pelvis counterclockwise between P4 and P5 and I think that he is super-efficient with respect to his ability to use his right-sided lateral pelvic rotator muscles to rotate his pelvis counterclockwise because he is "stabilising" his right leg/foot by maintaining a large degree of weight-pressure loading of his right leg/foot during his hip-squaring action. If he followed Tyler Ferrell's advice and quickly transferred his weight-pressure loading from the right foot => the left foot during the early downswing's P4 => P5 time period so that he already had 70% of his overall COP-measurement under his left foot, and only 30% of his overall COP-measurement remaining under his right foot, by the P5 position, then it is very likely that he could not use his right-sided lateral pelvic rotator muscles to rotate his pelvis counterclockwise with such great efficiency between P4 and P5.
If you believe that Dr.Kwon's theoretically-conceived Newtonian forces are causally responsible for rotating the pelvis counterclockwise during the hip squaring phase, then how can his theoretical model explain Luke List's counterclockwise pelvis rotation that happens between P4 and P4.5 if Luke List still has 76-85% of his overall COP measurement under his right foot during that hip-squaring phase time period, which means that he has only 15-24% of his overall COP measurement under his lead foot during the hip-squaring phase? Look at this video produced by Dr. Kwon - www.youtube.com/watch?v=fB2FQi1FyMg - and carefully watch what is happening between the 0.50 - 0.54 minute time point of the video. Note how the GRF moment produced by the right foot decreases between P4 and P4.5 while the GRF moment produced by the left foot dramatically increases. The moment arm also increases because the left foot's GRF moment is producing most of the GRF for the overall GRF moment (F), which surely necessitates that the theoretical golfer model must have most of his COP measurement under his lead foot during that hip-squaring time period. However, Luke List only has 15-24% of his overall COP measurment under his lead foot during his hip-squaring phase and I cannot understand how he could be generating the necessary GRF moment force that Dr.Kwon's theoretical model requires in order for it to induce a passive counterclockwise rotation of the pelvis that happens during the hip-squaring phase. Can you explain how it is possible!
Jeff.