|
Post by dubiousgolfer on Jul 26, 2022 19:10:22 GMT -5
|
|
|
Post by dubiousgolfer on Jul 27, 2022 19:19:01 GMT -5
This graph below showing lateral sway of the chest away from target at P6-P7 is something I've never heard of before. DG
|
|
|
Post by imperfectgolfer on Jul 27, 2022 22:40:52 GMT -5
This graph below showing lateral sway of the chest away from target at P6-P7 is something I've never heard of before. DG I don't know why you are surprised that the upper torso will move away from the target between P6 => P7 by a small amount (~1").
It is very common to see a pro golfer develop more secondary axis tilt with a slight reverse-C curvature of the spine in the later downswing when hitting a driver. Some will have so much that it causes their head to drop and move backwards away from the target.
Here are capture images of Tiger Woods - which I featured in my 2008 review paper on head movements.
Jeff.
|
|
|
Post by dubiousgolfer on Jul 28, 2022 5:13:30 GMT -5
Dr Mann
I've just found your article on your website.
"This composite image shows Tiger Woods at address (image1), at the end-backswing postion (image 2), and at impact (image 3). I placed red lines alongside his head at address, a blue dot over the position of the upper swing center, and the yellow line demonstrates his degree of spinal tilt (which varies at different time-points in the swing). Note that Tiger Woods has a slight degree of rightwards spinal tilt at address, and that causes his head to be vertically above a point on the ground that is behind the center of his stance. Note that Tiger Woods swivels his head to the right during the backswing, and that it allows him to get a full shoulder turn without the left shoulder hitting the chin. Note that his upper swing center doesn't move forward during the downswing, and that it is at the same location-point where it was located at address - despite a significant shift of the pelvis left-laterally. Note that his head drops down a lot during the downswing. However, note that the left side of his head never gets ahead of the left red line. Tiger Woods is not really disadvantaged by his excessive head dropping, which causes the cervical spine not to be aligned straight-in-line with the thoracic/lumbar spine, because it doesn't affect the position of the upper swing center."
Do you think Dr Phil Cheetham's findings that this is a 100% truth slightly over-hyped considering the data shows an average of 1inch backward chest sway from P6-P7? Personally, I try my best to adhere to what you've said on your website:
"A beginner golfer can learn a great deal about "correct" head movements from these capture images of these three professional golfers. He should understand that his key goal is keeping the upper swing center stationary near its address-position location throughout the backswing and downswing, and and that he should specifically avoid allowing the upper swing center to move ahead/forward in the direction of the target in the downswing. He can achieve that goal by ensuring that the left side of his head/face never moves ahead/forward in the direction of the target during the downswing. He should also realise that it is perfectly acceptable to allow the head to swivel horizontally away from the target during the backswing if it allows him to avoid having the left shoulder bump forcefully against the chin. He should also realise that the right side of the head will have a natural tendency to tilt in the direction of the ground during a full driver downswing, and that his head may even drop down slightly."
DG
|
|
|
Post by imperfectgolfer on Jul 28, 2022 6:40:10 GMT -5
Dr Mann I've just found your article on your website. "This composite image shows Tiger Woods at address (image1), at the end-backswing postion (image 2), and at impact (image 3). I placed red lines alongside his head at address, a blue dot over the position of the upper swing center, and the yellow line demonstrates his degree of spinal tilt (which varies at different time-points in the swing). Note that Tiger Woods has a slight degree of rightwards spinal tilt at address, and that causes his head to be vertically above a point on the ground that is behind the center of his stance. Note that Tiger Woods swivels his head to the right during the backswing, and that it allows him to get a full shoulder turn without the left shoulder hitting the chin. Note that his upper swing center doesn't move forward during the downswing, and that it is at the same location-point where it was located at address - despite a significant shift of the pelvis left-laterally. Note that his head drops down a lot during the downswing. However, note that the left side of his head never gets ahead of the left red line. Tiger Woods is not really disadvantaged by his excessive head dropping, which causes the cervical spine not to be aligned straight-in-line with the thoracic/lumbar spine, because it doesn't affect the position of the upper swing center."Do you think Dr Phil Cheetham's findings that this is a 100% truth slightly over-hyped considering the data shows an average of 1inch backward chest sway from P6-P7? Personally, I try my best to adhere to what you've said on your website: "A beginner golfer can learn a great deal about "correct" head movements from these capture images of these three professional golfers. He should understand that his key goal is keeping the upper swing center stationary near its address-position location throughout the backswing and downswing, and and that he should specifically avoid allowing the upper swing center to move ahead/forward in the direction of the target in the downswing. He can achieve that goal by ensuring that the left side of his head/face never moves ahead/forward in the direction of the target during the downswing. He should also realise that it is perfectly acceptable to allow the head to swivel horizontally away from the target during the backswing if it allows him to avoid having the left shoulder bump forcefully against the chin. He should also realise that the right side of the head will have a natural tendency to tilt in the direction of the ground during a full driver downswing, and that his head may even drop down slightly."DG I am presently far less rigid about the "idea" of keeping the upper swing center in the same place throughout the downswing. I think that it is perfectly OK for the upper swing center to move away from the target in the later downswing to a small degree - due to the acquisition of secondary axis tilt +/- right lateral bend. Jeff.
|
|
|
Post by imperfectgolfer on Jul 29, 2022 9:43:22 GMT -5
I watched this video. I then watched this SportsBox video. That Sportbox video claims that you can take a face-on swing video captured from an iPhone and then view 3D visuals from 6 different angles that are created from that face-on 2D video. How is that possible? I have been repeatedly mocked by 3D enthusiasts (eg. Jon Sinclair) who stated that I cannot mentally reconstruct what is happening in a full golf swing in terms of body/arm motions by simply analysing a 2D swing video taken from multiple angles. So, then how is it possible for this Sportsbox app to create 3D visuals that are derived from a 2D video taken only from a face-on viewing perspective? Jeff.
|
|
|
Post by dubiousgolfer on Jul 29, 2022 11:45:56 GMT -5
Dr Mann
I don't know how the technology works but Dr Phil Cheetham's video below understands that 3D is better than 2D, so he must be convinced that this 'Artificial Intelligent' app has some merit.
I will investigate further as I'm also interested in how they map 2D images to 3D.
DG
|
|
|
Post by imperfectgolfer on Jul 29, 2022 23:36:46 GMT -5
I have now watched the 2nd video listed by DG. Phil Cheetham states that 100% of pro golfers have pelvis/chest sway towards the target at P4, actually starting at ~P3.8, and that it precedes the turning of the body. At the 18:22 minute time point of the video PC states that it i) increases downswing loading of the club, ii) increases weight transfer to the lead leg and iii) potentially increases clubhead speed by increasing the release of the club. What? What is meant by the term "downswing loading of the club"? How does body sway produce that phenomenon? When he states weight transfer to the lead leg, we know that there is very little shift of the body's COM during the downswing. I can understand that one may want to increase the COP measurement under the lead foot, but I cannot understand why one would want to transfer weight to the lead side! Increase the release of the club!!! What? How can a small degree of sway (happening prior to body rotation) increase the release of the club? I think that PC's claims are totally unscientific and even incomprehensible. At the 22:19 minute time point of the video, PC states that 100% of tour pros lean away from the target at impact. That's not a new discovery. When swinging a driver at high clubhead speeds, the momentum of the released club in a targetwards direction is exerting a large pull, and a golfer must brace himself to prevent becoming unbalanced. Bracing happens at the level of the lead leg/pelvis and it also makes sense that the upper body must lean away from the target and this is not a new discovery. At the 28:48 minute time point, David Leadbetter states that an "OTT move" could be due to a golfer's response to having an open clubface at impact. I disagree! I think that the major cause of an "OTT move" is a disordered kinematic sequence where the upper torso rotates before the pelvis. I suspect that only a minority of amateur golfers who have an "OTT move" swing fault deliberately change their kinematic sequence in order to prevent a slice due to an open clubface at impact. Jeff.
|
|
|
Post by dubiousgolfer on Jul 30, 2022 8:40:49 GMT -5
Dr Mann I'm also finding Dr Phil Cheetham's statements a bit too vague to fully understand but my best guess is: 1. Increased loading of shaft? Unsure what that means other than increased lagging shaft bend which means increased positive torque by the time the club reaches P4. 2. I think he meant weight pressure shift rather than weight shift. 3. I can understand theoretically how lateral shift of the upper body can increase the lead arm speed (from Jorgenson's book 'The Physics of Golf' using a double-pendulum model) but it doesn't need to happen at P3.8 but rather at P4 when the left arm is more vertical and not moving clockwise at the time. Anyhow, the increase in clubhead speed would be very small for such a few inches lateral chest sway and it must happen before the lead arm gets to P5. Does increasing lead arm (and therefore hand) speed also increase the potential release of the club? I suspect yes, but the increase would be very small related to just chest sway. Maybe he means the shift assists in achieving the 'stretch-shorten cycle' effect (see this presentation slide below). Therefore, creating more force/torque to increase clubhead speed DG
|
|
|
Post by imperfectgolfer on Jul 30, 2022 9:20:40 GMT -5
Dr Mann I'm also finding Dr Phil Cheetham's statements a bit too vague to fully understand but my best guess is: 1. Increased loading of shaft? Unsure what that means other than increased lagging shaft bend which means increased positive torque by the time the club reaches P4. 2. I think he meant weight pressure shift rather than weight shift. 3. I can understand theoretically how lateral shift of the upper body can increase the lead arm speed (from Jorgenson's book 'The Physics of Golf' using a double-pendulum model) but it doesn't need to happen at P3.8 but rather at P4 when the left arm is more vertical and not moving clockwise at the time. Anyhow, the increase in clubhead speed would be very small for such a few inches lateral chest sway and it must happen before the lead arm gets to P5. Does increasing lead arm (and therefore hand) speed also increase the potential release of the club? I suspect yes, but the increase would be very small related to just chest sway. Maybe he means the shift assists in achieving the 'stretch-shorten cycle' effect (see this presentation slide below). Therefore, creating more force/torque to increase clubhead speed DG You wrote-: " Does increasing lead arm (and therefore hand) speed also increase the potential release of the club? I suspect yes, but the increase would be very small related to just chest sway." I do not believe that increasing the speed of lead arm release necessarily increases the efficiency of release of PA#2. I also do not believe that a few inches of targetwards sway of the torso increases the speed of release of PA#4. I have zero sympathy for the stretch-shorten cycle theory as it pertains to the lead shoulder joint and lead wrist joint. They also only measured an average of ~3 degrees of dynamic X-factor stretch which is very small and probably insignificant. Even if PC meant weight pressure shift, there is no evidence that increasing the vertical GRF under the lead foot in the early downswing increases clubhead speed. I also do not believe that a few inches of sway will necessarily increase the vertical GRF under the lead foot anyway because it is possible to sway without increasing the pressure-loading of the lead foot. Jeff.
|
|
|
Post by dubiousgolfer on Jul 30, 2022 11:12:13 GMT -5
Dr Mann
You said: "I do not believe that increasing the speed of lead arm release necessarily increases the efficiency of release of PA#2"
The release of PA#2 is dependent on the 'In Plane MOF' caused by the 'Net Force' across the grip by the hands. If the lead hand is moving in a curved path the centripetal force causing it to curve will be more normal to the hand path. That centripetal force contributes in part to that 'NET Force', which in turn generates the 'In Plane MOF' which causes the release of PA#2.
The centripetal force will be greater as the hand speed in the curved path increases.
Keeping the above in mind, now consider these 2 scenarios:
1. A golfer's lead hand moving at 20mph as it reached release point ~P5.5 (with a PA2 angle of 90 degrees) and then suddenly changes in a more curved direction. 2. A golfer's lead hand moving at 10mph as it reached release point ~P5.5 (with a PA2 angle of 90 degrees) and then suddenly changes in the same curved direction as in point 1.
Wouldn't the PA#2 release be greater in point 1 than point 2?
DG
|
|
|
Post by imperfectgolfer on Jul 30, 2022 11:48:17 GMT -5
Dr Mann You said: "I do not believe that increasing the speed of lead arm release necessarily increases the efficiency of release of PA#2" The release of PA#2 is dependent on the 'In Plane MOF' caused by the 'Net Force' across the grip by the hands. If the lead hand is moving in a curved path the centripetal force causing it to curve will be more normal to the hand path. That centripetal force contributes in part to that 'NET Force', which in turn generates the 'In Plane MOF' which causes the release of PA#2. The centripetal force will be greater as the hand speed in the curved path increases. Keeping the above in mind, now consider these 2 scenarios: 1. A golfer's lead hand moving at 20mph as it reached release point ~P5.5 (with a PA2 angle of 90 degrees) and then suddenly changes in a more curved direction. 2. A golfer's lead hand moving at 10mph as it reached release point ~P5.5 (with a PA2 angle of 90 degrees) and then suddenly changes in the same curved direction as in point 1. Wouldn't the PA#2 release be greater in point 1 than point 2? DG I was very careful in how I phrased my statement by using the word "necessarily" and by also using the term "efficiency" with respect to the release of PA#2. In other words, if one doubles the hand speed by P5.5 it will not necessarily double the speed of release of PA#2. One has to also take into account the shape of the hand arc path - whether it is U-shaped or V-shaped. If it is too V-shaped, then a faster hand speed at P5.5 may actually cause an increasingly inefficient release of PA#2 - especially if the hands do not slow down between P5.5 => P7. I can easily accelerate my hands very fast between P4 => P7 to such an exaggerated degree that I come into impact with the clubshaft lagging so far behind that I have an excess degree of forward shaft lean and a very open clubface at impact, thereby leading to weak push-sliced shots. An initial sway of the body at transition does not necessarily increase the speed of release of PA#4 and/or help a golfer to shape his hand arc for a more efficient release of PA#2. Jeff.
|
|
|
Post by dubiousgolfer on Oct 17, 2022 18:07:40 GMT -5
Just saw another recent Sportsbox AI video which I found quite interesting, and it seems to be evolving as they capture more golf swing image data.
DG
|
|
|
Post by imperfectgolfer on Oct 19, 2022 11:19:14 GMT -5
Just saw another recent Sportsbox AI video which I found quite interesting, and it seems to be evolving as they capture more golf swing image data. DG Some comments. How does Sportsbox convert a 2D video to 3D data? Phil stated that he trained the Sportsbox's "artificial intelligence" by using his data base of TPI-AMM 3D-data from his study of pro golfers. However, he then stated later in the video that there are differences between the 3D data produced by Sportsbox and his AMM-based 3D system. He did not elaborate on the degree of difference. That is concerning because it puts into question the accuracy of Sportsbox's "artificial intelligence machine". I think that a major problem is that Sportsbox can potentially produce hundreds of 3D data points, but it does not know what is causing the body/arm motions that produce those data points. This is likely going to cause a large level of consternation when different golf instructors come up with (invent) different theories as to the link between body kinetics and body kinematics. Take, as example, the idea that a skilled golfer should lift-and-sway the pelvis between P1 => P4 as seen in Kyle Berkshire's driver swing action. I think that his measurements are hugely affected by his stance width (which is much wider than his pelvic width) and his high level of flexibility/athleticism. However, that does not mean that a skilled amateur golfer must also sway/lift the pelvis between P1 => P4. Phil Cheetham stated that the pelvis should start to drop between P3 => P4 and reach its maximum drop at ~P5. Then, it should start to lift between P5 => P7 reaching its maximum lift after impact. That's not a new insight, and I recommended that pelvic motional pattern years ago in my review paper at perfectgolfswingreview.net/pelvicrotation.html . Elevating the left side of the pelvis between P5 => P7 helps to elevate the left shoulder shoulder socket and that causes the lead hand arc path to move upwards after P5.5/P6 thereby creating a greater degree of the centripetal component of the lead hand's MoF, which is causally responsible for producing a very efficient release of PA#2 between P5.5 => P7. However, there is no direct correlation between the degree of pelvis lift and the degree of lead shoulder socket elevation because of the variable of secondary axis tilt combined with right lateral bend. Look at Kyle Berkshire's driver swing and note how his lead shoulder socket is far behind his lead foot at impact - see 43:38 minute time point of the video. Interestingly, note that he positions his ball well inside his lead foot at address - and that allows his lead arm/clubshaft to be roughly vertical at impact considering how much his lead thigh is slanted away from the target at impact and how much secondary axis tilt he has at impact. That is very different to Scottie Scheffler's driver swing action. Note that Scottie positions his ball just inside his lead foot. Note that his lead shoulder socket is vertically above the ball position at impact and it is not far back at impact (as seen in Kyle Berkshire's impact image). With so many body motion/body position variables in play, I cannot clearly understand how Sportsbox is going to improve the quality of golf instruction.
Jeff.
|
|
|
Post by dubiousgolfer on Dec 8, 2023 8:15:39 GMT -5
Just thought I'd add this Phil Cheetham Sportsbox explanation of Chest Side Bend. I am really confused about this because I thought the AC joints can be moved independent of each other by the scapula, therefore how can this be associated with 'Chest Side Bend'? Also , other body movements could cause that 'line' connecting the AC joints to change its inclination with the horizontal plane (such as pelvic tilt). ---------------------------------------------------------------- "There's been a lot of talk about chest (aka Ribcage or Thorax) side bend lately so I thought I would contribute to the discussion with some more info. This is a slide we use in our Sportsbox Level 1 Certification. Sportsbox also uses the AMM standard 3D model and algorithms. Basically, if you draw a line between the two Acromioclavicular (AC) joints, side bend is the angle the line makes with the horizontal plane, and it follows you as you turn. The table is data from the AMM tour pro driver database and if you look at the graph you see that lead (left) side bend typically maxes out before top of backswing and maintains a similar angle until early downswing. Some golfers (like Rory) increase the lead (left) side bend a little more early in the downswing before rapidly progressing to trail (right) side bend at impact. Notice that side bend actually reaches max after impact. You can see this from the numbers in the table and the graph. Hope this helps." "This is just one measurement and most measurements in the body are connected to what’s happening below. There are two specific measurements that AMM, Sportsbox and most golf 3D analysis systems make. They are segment angles and joint angles so if you want to see what’s contributing to the chest side bend, you can also look at the spine side bend, and the pelvis side bend. But that’s not to say that the chest side bend measurements don’t give significant information, they do. The measurement in the slide is the side bend of the chest, but remember the chest sits on the pelvis so if the chest stayed stationary and the pelvis tipped and took it with it then yes, the pelvis affects the side bend number as well. If you want to just look at the side bend of the chest relative to the pelvis that is called spine bend. And there’s another set of data available for that. Gears Sportsbox and AMM all measure side band as well as several other systems." ---------------------------------------- DG PS. Why do the biomechanics scientists make everything so confusing with different terminology and measurement definitions . It's a mess!!! I am suspecting that the table above is from AMM3D which has sensors whose mid-point is around the T4 vertebrae. But that Sportsbox is going to use the line between the AC joints in contrast to the way AMM3D and GEARS conducts it's measurement of chest/thorax side bend. So why did PC say " Sportsbox also uses the AMM standard 3D model and algorithms"? The fact he is using a different way to measure 'chest side bend' seems to contradict that statement unless 'standard model' means something else.
|
|