Analysing Milo's side-bend video

[imperfectgolfer]

Another puzzling Michael Neff claim.

Go to the 7:26 - 7:36 minute time point of the Neff video where he claims that the hand arc path will curve more towards the ball after P5 due to the fact that the ribcage side-bend measurement starts moving in the direction of rightwards side-bend.

I think that's not true and I think that major factor causing the hand arc path to move more targetwards after ~P5 is due to the fact that the lead arm starts to move more towards abduction between P5 => P5.5 - see what is happening between image 3 and image 4 in the following capture images of Rory's driver golf swing action.

Jeff.

[dubiousgolfer]

Here are the screen images of that AMG video comparing the scratch golfer to Sergio (Top left) , Rory (Bottom Left) , DJ (Top Right) , Lydia Ko (Bottom Right).

The body positions of all are at impact and one can compare ribcage side bend between the scratch golfer and the tour pros. They are saying from 18:13-18:26 that the pro's have more ribcage side-bend because of greater spine tilt and pelvis side-bend.




If you look at the spinal tilt angle differences between the scratch golfer and tour pros , it almost matches the differences in the ribcage side bend , therefore the difference in ribcage values could just be all about spine tilt , not necessarily extra ribcage side-bend like the bottom image below.

I can imagine that there is real anatomical ribcage-side bend happening in the tour pros (like bottom image below) compared to the scratch golfer but I don't think GEARS is measuring it in a way that mirrors what is actually anatomically happening in the golfers spine.





With regards Rory one can see that the ribcage side bend doesn't change much from P3-P5 but the AMG video is recording a significant change from P4-P5 (see images below- Rory is in the middle of the AMG screen video images).

Could it be that AMG and Mr Neff have recorded swings of Rory at different points in his career where he might have changed his swing mechanics?





DG

[dubiousgolfer]

Dr Mann

Michael Neff has replied back to me and says the email I sent to Dr Phil Cheetham and Greg Rose does raise some questions.

He said the following:

"I think this would be a good video for our biomechanist Kait Jackson and I to do together

We will make one on this next week during our internal summit"


DG

[imperfectgolfer]

DG,

This post appeared on the GolfWRX thread on this topic.

"The scratch golfer seemed to have virtually zero ribcage side bend when he was rotating around an approximately vertical spine so why should rotating around a forward tilted spine make any difference?"

This represents my answer.

Consider this upline series of capture images of Dustin Johnson.

Image 1 is at P3, image 2 is at P3.3, image 3 is at P3.6, image 4 is at P4, and image 5 is at P4.25.

I have drawn a blue line to show the lumbar spine bend angle and the red line represents the thoracic spine bend angle - relative to the ground.

The side numbers in each image reflect the degrees of bend - thoracic spine on top, and lumbar spine below.

Note that the measurement can only be accurate when the spine is perpendicular to the upline camera position, and parallax error accounts for some of the differences between different P positions. The most accurate readings are probably in image 3 - so as a generalisation one can note that his lumbar spine is at a 45 degree angle to the ground while the thoracic spine is at a 34 degree angle relative to the ground.

Why is the T-spine angled ~11 degrees more than the L-spine?

I think that it is due to the fact that the T spine rotates far more clockwise than the L-spine (which can only rotate clockwise as much as the pelvis) during the backswing and that causes the T-spine to angle slightly more groundwards as it rotates clockwise. This unconscious (non-deliberate) phenomenon will also apply to that scratch golfer who simply turned clockwise.

Note that I have drawn a green line down his T-spine and it is ~10 degrees angled relative to his L-spine (blue line).

GEARS measures rib cage side-bend as a "line" that is perpendicular to that green line and it then measures the angle between that "line" and the ground.

Their rib cage side-bend measurements change between P1 => P4 because that green line continuously changes its angle relative to a upline/DTL camera position. 

Jeff.

[dubiousgolfer]

Dr Mann

Yes, that makes perfect sense.

DG