Shoulder rotation in a pivot-driven swing - LynnBlakeGolf Forums

Shoulder rotation in a pivot-driven swing

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  #1  
Old 01-08-2009, 11:27 AM
Jeff Jeff is offline
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Shoulder rotation in a pivot-driven swing
I would like to hear of different opinions/experiences regarding shoulder rotation in a pivot-driven swing.

In a pivot-driven swing, the pivot action should start with a lower body shift rotation move that causes the pelvis to shift left-laterally. That causes the lumbar spine to also move left-laterally and if the head is kept stationary a golfer develops increased rightwards spinal tilt (secondary axis tilt). That, in turn, allows the right shoulder to move downplane when the upper torso subsequently rotates.

Two questions:

1) How much of your shoulder (upper torso) rotation is due to active contraction of mid-upper torso muscles and how much is due to passive forces being transferred from the lower body to the upper body via the spine and external torso muscles/ligaments?

2) Here is a diagram showing the kinetic sequence. I have placed small photos of Aaron Baddeley's swing in the diagram showing my perception of when his his pelvis and shoulder rotation reach their peak rotational speed.



When do you think that your shoulder rotation reaches its peak rotational speed in your swing?

Jeff.
  #2  
Old 01-12-2009, 01:35 AM
biomechanic biomechanic is offline
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Jeff,
Your picking at Straws, with out measuring what arron is doing your guessing and picking at straws, no one can predict or tell with out measuring when aarons shoulders peaks.
You still don't get it do you Jeff, leave biomechanics to the real experts Jeff
  #3  
Old 01-12-2009, 11:26 AM
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12 piece bucket 12 piece bucket is offline
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Who are the "real experts"?
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Old 01-12-2009, 05:39 PM
biomechanic biomechanic is offline
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Originally Posted by 12 piece bucket View Post
Who are the "real experts"?
Bucket,
Jeff's not that's for sure. Experts who acutally studied and trained in human body motion and biomechanists. If you speak to guys like us we for starters don't use the incorrect terminology Jeff does that's for sure.
One thing which annoys me is one it's an insult to T.G.M cause this is a mechanical site and it's insults to human body motion as well. He's combining the two. Body motion and mechanics are worlds apart and should be kept that way.
You can have a non golfer have a perfect kinetic chain but can't play golf. They need to be taught mechanics.
You can have a T.G.M guy with perfect mechanics but have poor kinetic link.
This person need to learn body motion.
They are two worlds which need to be kept separate.
Bucket have you ever seen a biomechanist teaching golf. No they measure and teach body motion, not mechanics same with golf coaches they teach mechanics not body motion, And both of them should stay out of each others back yard
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Old 01-13-2009, 12:06 AM
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12 piece bucket 12 piece bucket is offline
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Originally Posted by biomechanic View Post
Bucket,
Jeff's not that's for sure. Experts who acutally studied and trained in human body motion and biomechanists. If you speak to guys like us we for starters don't use the incorrect terminology Jeff does that's for sure.
One thing which annoys me is one it's an insult to T.G.M cause this is a mechanical site and it's insults to human body motion as well. He's combining the two. Body motion and mechanics are worlds apart and should be kept that way.
You can have a non golfer have a perfect kinetic chain but can't play golf. They need to be taught mechanics.
You can have a T.G.M guy with perfect mechanics but have poor kinetic link.
This person need to learn body motion.
They are two worlds which need to be kept separate.
Bucket have you ever seen a biomechanist teaching golf. No they measure and teach body motion, not mechanics same with golf coaches they teach mechanics not body motion, And both of them should stay out of each others back yard
Sounds good to me . . . . But who are they?
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  #6  
Old 01-13-2009, 12:40 PM
Jeff Jeff is offline
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12PB

Biomechanic works for Chris Welch of Zenolink.

If you want to understand what Zenolink measures, you can view the top two webinars videos at the following Zenolink website.

http://welch-e.com/welch-e/webinars....ntent=webinars

They get their clients to video a golfer using two video cameras (operating at 30-60 frames/second) at nearly right angles to each other. They then use the video data to project the golfer's movements in space from a 3-D perspective.

Here is a link showing the camera setup arrangement.

http://www.lousolarte.com/3dbiomechanics.html

Here is the type of graph they produce regarding angular speeds - derived from that top webinar.



Now, you may find this type of graph convincing, but I do not because of their method of measuring angular velocity.

This is their method of measuring angular velocity - according to an article by TPI.

"The angular velocities for the kinetic link are calculated as follows: A pelvis origin is defined as a point mid way between the hip joints; an upper body origin is defined as a point mid way between the left and right shoulder joints; a fixed spine axis is defined as the line from the pelvis and upper body origins. A plane is produced perpendicular to the spine axis at the level of the pelvis origin; call it the “perpendicular to spine” plane (the PTS plane). A vertical plane parallel to the target line is defined to cut through the PTS plane; the line this produces on the PTS plane is used as the zero reference line. A line in the pelvis from hip joint to hip joint is projected into the PTS plane. A line in the upper body from shoulder joint to shoulder joint is projected into the PTS plane. Finally a line is created from the mid shoulder point to the mid hands on the club grip (called the “composite arm” line) and it is also projected into the PTS plane. These three lines allow a rotation angle to be calculated between each one and the zero reference line. Segmental rotation speeds are calculated as the time rate of change of these angles. "

Here is a diagram showing how they project the composite arm onto the PTS plane in order to create angular velocity measurements.



The circular blue line represents the PTS plane. They then apparently project the composite arm's movement onto the PTS plane in order to calculate their angular velocity measurements. However, I think that this methodology is very problematic because the arms mainly swing downwards (more than outwards) after release of PA#4. That means that the plane the left arm is swinging along is at a large out-of-plane angle relative to the PTS plane and I think that it will cause "projection errors" of great magnitude.

Don't you think that it makes their arm speed angular velocity values incorrect? I think that one needs to measure the angular velocity of the arms along a plane that is perpendicular to the axis of rotation of the left arm, and that plane is not parallel to the PTS plane. I think that even their shoulder rotation measurements must be incorrect because the right shoulder moves downplane and doesn't move along a plane that is parallel to the PTS plane.

Jeff.

Last edited by Jeff : 01-14-2009 at 12:26 AM. Reason: added link, correct spelling
  #7  
Old 01-12-2009, 01:07 PM
O.B.Left O.B.Left is offline
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Originally Posted by Jeff View Post
I would like to hear of different opinions/experiences regarding shoulder rotation in a pivot-driven swing.

In a pivot-driven swing, the pivot action should start with a lower body shift rotation move that causes the pelvis to shift left-laterally. That causes the lumbar spine to also move left-laterally and if the head is kept stationary a golfer develops increased rightwards spinal tilt (secondary axis tilt). That, in turn, allows the right shoulder to move downplane when the upper torso subsequently rotates.

Two questions:

1) How much of your shoulder (upper torso) rotation is due to active contraction of mid-upper torso muscles and how much is due to passive forces being transferred from the lower body to the upper body via the spine and external torso muscles/ligaments?

2) Here is a diagram showing the kinetic sequence. I have placed small photos of Aaron Baddeley's swing in the diagram showing my perception of when his his pelvis and shoulder rotation reach their peak rotational speed.



When do you think that your shoulder rotation reaches its peak rotational speed in your swing?

Jeff.

The two questions relate to circle path swings too though no? No axis tilt.

Not to nit pick but the whole axis tilt thing is about tilting the shoulders. I think this is what promotes the on plane move of the right shoulder.

I like your question No.1. I used to really spin my hips hard but dont anymore. Certainly the hips lead but........behond that I dont know. I now feel like I hit the ball more with my right shoulder than my hips, swinging or hitting.

Last edited by O.B.Left : 01-12-2009 at 01:10 PM.
 


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