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Post by utahgolfer on Apr 6, 2020 22:47:36 GMT -5
is there any practical value for swinging through impact with a straight versus bent left leg? Most PGA pros appear to favor a straight left leg, but we will still see some pros maintain a bent knee through impact.
Here are two examples:
At p7, both pros appear to have pretty level left shoulders, but CC has a more elevated left hip and BD have a more level left hip. After impact, CC has a more elevated left shoulder and left hip, while BD has a more level left hip and left shoulder.
My guess is that this micro-move has some bearing on the swing mechanics.
It seems like a straight left leg at impact helps to get the left pelvis turning sharply behind the player to prevent lateral slide. Maintaining a bent knee, like BD, promotes a greater pelvic slide to the left, whereas CC demonstrates pure pelvic rotation with no pelvic slide to the left.
A straight left leg at and beyond impact also appears to cause the left shoulder to elevate more as it rotates CCW as seen in CC's swing, while BD's bent left leg promotes a more level shoulder turn during the follow-through.
Here are some questions regarding this topic, all else being equal:
--Is a CP release easier to perform with more level turning shoulders? --Does a more elevated left shoulder cause a greater deceleration of the left arm? --Is a hook more likely with an elevated left pelvis and elevated left shoulder? --Is a slice more likely when the pelvis slides more to the left and the left shoulder rotates more level? --Is a bent left knee at a higher risk of injury versus a straight left knee? --Is it easier to fully rotate the hips/pelvis when the left pelvis is not elevated?
Any input is appreciated.
UG
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Post by dubiousgolfer on Apr 8, 2020 10:17:04 GMT -5
Hi UG - I'll have a go but you'd best wait for Dr Mann's response.
1st question : CP release requires that the upper arms are closely connected to the actively rotating upper torso. So I suspect it depends on the rotational plane of the torso rather than the independent shoulder plane rotations .
2nd question: An elevated left shoulder doesn't imply that there has been some dynamic force/torque activity that might decelerate the left arm.
3rd question: Unsure whether an elevated left 'pelvis/shoulder' would causes a change in club path and clubface orientation to cause a hook . I would have thought a mix of non-optimal biomechanics that determine clubshaft to swing on plane, timing of the release of PA accumulators, and high ROC hand release action can all contribute to errant strikes (including hooks).
4th question: If the pelvis slides too early to the left , I would have thought it would cause a pressure load of the left hip and impede the CCW rotation of the pelvis (via the contraction of the pelvic rotary muscles). To help CCW pelvic rotation, the golfer might have to activate their gluteus maximus muscles and 'early extend' . If the pelvis slides such that the left hip bypasses the left knee , then the golfer may have to use a 'butt tuck move' (like S&T) under the spine towards the right of the target to allow the arms to swing to impact. I'm unsure whether this non-optimal pelvic movement would make the shoulder rotate more level and I don't know whether this would guarantee a slice.
5th question: Don't know 6th question: If the left hip is elevated too early in the downswing I imagine the left leg will be more extended , therefore activating the gluteus maximus muscles to further extend the leg and rotate the left side of the pelvis might be limited.
DG
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Post by imperfectgolfer on Apr 11, 2020 15:12:31 GMT -5
UG,
You asked-: "is there any practical value for swinging through impact with a straight versus bent left leg? Most PGA pros appear to favor a straight left leg, but we will still see some pros maintain a bent knee through impact."
I do not have a sufficiently deep understanding of this issue to know how to correctly answer your question.
Jeff.
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Post by dubiousgolfer on Apr 15, 2020 9:18:57 GMT -5
Dr Mann
I have been reviewing your 'Educational Review: Michael Finney's Golf Swing Kinetics Seminar' article and 'How To Optimally Rotate The Pelvis In the Downswing' .
I was particularly interested in these other muscle groups on the left side that assist pelvic rotation.
1. Early downswing from P4-P5 (hip squaring phase with a lesser pressure loaded left leg/hip) a. Contraction left sided pelvic rotary muscles that externally rotate the left femur coupled with (b) below b. Isometric contraction of the adductor magnus muscle that pull the left inferior pubic ramus towards the left thigh (as it is being externally rotated).
2. From P5.5 a. Isotonic contraction of the left vastus lateralis muscle that forms a large part of the left quadriceps muscle group in the anterior compartment of the left thigh . When it contracts it extends the left knee, and it also braces the left knee so that it doesn't buckle/bend sideways. b. Isotonic contraction of left gluteus maximus muscle, and it is attached medially (at its origin) to the outer (lateral) left edge of the sacrum and to a significant section of the posterior pelvic crest and it inserts at the back of the upper left femur. When that muscle contracts it pulls the left upper femur towards the sacrum (midline) and thereby contributes to the counterclockwise rotation of the left hip joint away from the target as the left hip joint extends. c. Another biomechanical factor that contributes to the continued counterclockwise rotation of the pelvis in the later downswing is the fact that the left adductor magnus muscle is still actively contracting and it pulls the left inferior pubic ramus (and therefore the left side of the lower pelvis) closer to the left femur. During the later downswing, the pelvis rotates counterclockwise more than the left femur, so that the left femur becomes progressively more internally rotated in the left hip joint, and isotonic contraction of the left adductor magnus muscle is continuously pulling the left femur and the left-lower pelvis closer together during this time period.
I have a few questions:
For point 2c - Did you mean the left femur becomes more externally rotated in the left hip joint because the pelvis rotates CCW more than the left femur? That the isotonic contraction of the adductor magnus is responsible for 'closing that external rotation' to become more internally rotated?
Addendum : Now I understand what you meant in point 2c above (ie. internally rotated) so struck through.
For point 2a & 2b - I can understand how those muscles will brace and extend the knee and extend the upper left femur and also externally rotate the femur but I cannot understand how those muscle contractions will rotate the pelvis CCW.
The only way I can visualise 2a & 2b pushing the left hip up and back is if the left leg (including ankle) is first angulated away from the 'target & target line' so that the muscle contractions cause a 'reactionary' push off the 'inside left foot' partially 'right of target & away from ball-target line' (using the impedance and frictional forces between foot and ground).
Won't doing 2a & 2b with a 'less angulated left leg position' (ie. still flexed knee but ankle and thigh more vertically aligned from a 'face on' view , while ankle more vertical aligned from a 'dtl view) just cause pelvic elevation? I am also assuming doing 2c with a less angulated left leg position won't stop internal rotation of left femur.
DG
PS. On reflection , I don't think it is biomechanically possible for the left ankle to be angulated away from the ball-target line before extension of femur /knee in the downswing from P5.5. But it can be angulated away from the target.
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Post by dubiousgolfer on Apr 15, 2020 10:35:44 GMT -5
Ben Hogan doesn't seem to have an angulated ankle away from target by P5.5 so I must be wrong.
DG
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Post by imperfectgolfer on Apr 15, 2020 10:41:42 GMT -5
DG, You wrote-: " For point 2a & 2b - I can understand how those muscles will brace and extend the knee and extend the upper left femur and also externally rotate the femur but I cannot understand how those muscle contractions will rotate the pelvis CCW." If the left femoral head moves upwards, and also slightly away from the target, due to straightening of the left leg will it not cause the left hip joint area of the pelvis to also move in the same direction by the same amount? Jeff.
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Post by dubiousgolfer on Apr 15, 2020 11:22:08 GMT -5
Dr Mann
The contraction of the left gluteus maximus can cause external rotation of the femur in the hip joint . Therefore can one assume that the combination of the isotonic contraction of the adductor magnus (while the femur is externally rotating caused by the gluteus maximus contraction) can cause rotation of the left side of pelvis?
When one sits on a chair and stands up, you first bend forward so that your COM is more centred under your feet and then activate the gluteus maximus to extend the thigh in the hip joint, but all it does is elevate the pelvis upwards. I couldn't understand how muscles that extend the femur can rotate the pelvis but the above makes sense.
DG
PS. I think I am getting confused with all these muscles :-(
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Post by imperfectgolfer on Apr 15, 2020 12:22:47 GMT -5
Dr Mann The contraction of the left gluteus maximus can be a lateral rotator of the femur in the hip joint . Therefore can one assume that the combination of the isotonic contraction of the adductor magnus (while the femur is externally rotating caused by the gluteus maximus contraction) can cause rotation of the left side of pelvis? When one sits on a chair and stands up, you first bend forward so that your COM is more centred under your feet and then activate the gluteus maximus to extend the thigh in the hip joint, but all it does is elevate the pelvis upwards. I couldn't understand how muscles that extend the femur can rotate the pelvis but the above makes sense. DG PS. I think I am getting confused with all these muscles :-( Contraction of the left adductor magnus will assist in the counterclockwise rotation of the pelvis, but the pelvis will still rotate if the left straightens while the right knee bends. Sit in a chair and then stand up, and you will note that both hip joints elevate the same amount and there is no pelvic rotation. Then repeat the experiment, but when standing up only straighten the left leg while allowing the right leg to passively hang from the right hip joint, and you will note that your pelvis rotates when the left hip joint elevates due to the straightening left leg. Jeff.
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Post by dubiousgolfer on Apr 15, 2020 17:17:07 GMT -5
Dr Mann - tried that experiment and it didn't work - no pelvic rotation.
Looked at these videos and couldn't see any pelvic rotation.
I think that maybe the dominant rotation is the combination of external rotation of left femur using 'Gluteus Maximus' combined with isotonic contraction of 'Adductor Magnus'.
DG
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Post by dubiousgolfer on Apr 15, 2020 19:05:56 GMT -5
Just thought I'd add this video of the other adductor muscles apart from adductor magnus .
Is it not possible that all of them can isotonically contract while the gluteus maximus externally rotates the left femur (pulling against the pubic inferior and superior ramus)?
DG
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Post by imperfectgolfer on Apr 15, 2020 21:10:56 GMT -5
Dr Mann - tried that experiment and it didn't work - no pelvic rotation. Looked at these videos and couldn't see any pelvic rotation. I think that maybe the dominant rotation is the combination of external rotation of left femur using 'Gluteus Maximus' combined with isotonic contraction of 'Adductor Magnus'. DG DG, Try it again, but simultaneously contract the ipsilateral gluteus maximus muscle so that it induces a degree of external rotation of the ipsilateral femur - thereby trying to simulate the motion that you see in Ben Hogan's left femur/buttock in the following capture images. Jeff.
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Post by dubiousgolfer on Apr 16, 2020 8:28:32 GMT -5
Dr Mann
No , I cannot physically do it without tearing something.
However , I can stand just on my left leg, in balance, supporting my whole body weight and still rotate my pelvis CCW . I can feel mainly my adductor muscles contracting to perform the pelvic movement (and slightly in my gluteus maximus).
Is it not feasible that stabilising the left leg into the ground (to stop any external rotation in the hip socket) and then performing isotonic contractions of all the adductor muscles cause the pelvic CCW rotation?
DG
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Post by imperfectgolfer on Apr 16, 2020 9:12:35 GMT -5
Dr Mann No , I cannot physically do it without tearing something. However , I can stand just on my left leg, in balance, supporting my whole body weight and still rotate my pelvis CCW . I can feel mainly my adductor muscles contracting to perform the pelvic movement (and slightly in my gluteus maximus). Is it not feasible that stabilising the left leg into the ground (to stop any external rotation in the hip socket) and then performing isotonic contractions of all the adductor muscles cause the pelvic CCW rotation? DG Yes - I think that it is very feasible that the left-sided adductor muscles are partly responsible for continued pelvic rotation between P5.5 and P7. In fact, it may be the most important factor in some golfers and its overall efficacy may be partly related to whether a golfer has a straight versus a bent left leg at impact (although I cannot claim to know whether it is better to have a straight versus bent left leg at impact from the perspective of better utilising the adductor muscles). Jeff.
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