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Post by dubiousgolfer on Aug 24, 2019 18:55:49 GMT -5
Dr Mann There are still quite a few instructors who still promote 'horizontal forces/torques' via the feet to help rotate the pelvis in the downswing I understand your opinions about the pelvic rotary muscles being involved from P4-P5 in the hip squaring phase of the downswing (including the activation of the iliopsoas muscle to create right hip joint flexion and external rotation of the right femur) But is it also possible for golfers to actually torque their right foot clockwise, while doing a squat (using an eccentric contraction of the hamstrings -see image B below) that might weight pressure their right leg at the same time? Couldn't a golfer incorporate a mix of right foot torquing , pelvic rotary muscle contractions, activation of iliopsoas, eccentric contraction of hamstrings, and still achieve that same 'Sam Snead' squat look? So isn't it possible that a golfer could activate different muscles to get an identical 'Sam Snead Squat' look in the hip squaring phase ( I think they refer to this as a 'Closed Loop Problem')? DG
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Post by imperfectgolfer on Aug 24, 2019 23:54:36 GMT -5
Dr Mann There are still quite a few instructors who still promote 'horizontal forces/torques' via the feet to help rotate the pelvis in the downswing I understand your opinions about the pelvic rotary muscles being involved from P4-P5 in the hip squaring phase of the downswing (including the activation of the iliopsoas muscle to create right hip joint flexion and external rotation of the right femur) But is it also possible for golfers to actually torque their right foot clockwise, while doing a squat (using an eccentric contraction of the hamstrings -see image B below) that might weight pressure their right leg at the same time? Couldn't a golfer incorporate a mix of right foot torquing , pelvic rotary muscle contractions, activation of iliopsoas, eccentric contraction of hamstrings, and still achieve that same 'Sam Snead' squat look? So isn't it possible that a golfer could activate different muscles to get an identical 'Sam Snead Squat' look in the hip squaring phase ( I think they refer to this as a 'Closed Loop Problem')? DG How does thinking about an eccentric contraction of a muscle help you to understand golf swing biomechanics? If a muscle is lengthening then it is contracting less actively. So, if the right hip joint and right knee joint become more flexed between P4 and P5, why do you postulate an eccentric contraction of the hamstrings being a causative factor rather than postulate that the hip/knee flexor muscles are more active. Larry Cheung states that he wants to use the ground to rotate the pelvis counterclockwise, but he does not explain how this is possible. How does pushing down into the ground under the right foot (while rotating your right foot clockwise) rotate the pelvis counterclockwise - if one is only using ground forces? I think that he does not realize that he is actually using his right-sided lateral pelvic rotator muscles in his demonstration. I certainly believe that it is possible to simultaneously use ground reaction forces under the left foot to rotate the pelvis counterclockwise between P4 and P5 secondary to generating a horizontal GRM by pushing against the ground under the left forefoot in a direction that is away from the ball-target line. I think that George Gankas also does not understand that he is using his right-sided lateral pelvic rotator to rotate his pelvis counterclockwise between P4 and P5 when he squats into an exaggerated "Sam Snead sit-down" posture. I very much dislike George's teaching because he exaggerates the degree of left knee flexion and left femur external rotation, which causes the left knee to move too much targetwards and which causes the left hip joint to drop groundwards between P4 and P5. I much prefer the idea of starting to straighten the left leg by contracting the left quadriceps muscle while generating a horizontal GRM under the left foot, so that the left hip joint does not drop groundwards during the early downswing. George also wants his student-golfers to push off the right foot in the mid-downswing, and he believes that it will induce further pelvic rotation. I much prefer the idea that the counterclockwise pelvic rotation is being induced by i) the contraction of the right-sided lateral pelvic rotator muscles and ii) the contraction of the left quadriceps muscle inducing a straightening left leg (and horizontal GRM) between P4 and P5.5 followed by the iii) contraction of the left gluteus maximus muscle between P5.5 and impact - while keeping the right gluteus maximus muscle more quiescent.
Jeff.
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Post by dubiousgolfer on Aug 26, 2019 9:01:32 GMT -5
Many thanks Dr Mann
If golfers do try and create GRF forces as per Larry Cheung's advice, won't this cause pressure on the right knee? I can imagine a lot of torque required at knee level to rotate a heavy pelvic girdle.
DG
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Post by imperfectgolfer on Aug 26, 2019 11:54:20 GMT -5
Many thanks Dr Mann If golfers do try and create GRF forces as per Larry Cheung's advice, won't this cause pressure on the right knee? I can imagine a lot of torque required at knee level to rotate a heavy pelvic girdle. DG I agree with Larry that a golfer should be generating a lot of vertical force under the right foot during the early downswing and I don't think that will damage the right knee if the knee is pressure-loaded. Where I differ from Larry, is that I believe that the vertical GRF is used to "stabilise" the right leg/femur so that contraction of the right-sided lateral pelvic rotator muscles can be used to rotate the pelvis counterclockwise away from the weight-presssure-loaded, and therefore positionally-stabilised, right leg - and I do not believe that the vertical GRF being produced under the right foot can independently cause a counterclockwise pelvic rotation. Jeff.
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