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Post by dubiousgolfer on Jun 10, 2021 11:06:43 GMT -5
Dr Mann
Yes , you are correct that the force caused by muscular contractions can be thought of as being 'reflected' back from the ground through the body to create biomechanical motion.
The definition of constraint forces (from a purely physics perspective) is below and I've used it to describe the 'constraint' of further movement of the feet downwards into the ground.
"Constraint Forces are the forces that the constraining object exerts on the object to make it follow the motional constraints."
DG
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Post by imperfectgolfer on Jun 10, 2021 11:11:13 GMT -5
UG,
You stated-: "Cream always rises to the top and Scott Lynn appears to be top-rate cream in the world of biomechanics."
I disagree!
Watch how SC works on this first amateur golfer in this video - starting at the 56 minute time point.
He states that the golfer has a clubhead path that is too much in-to-out (~6.9 degrees) at impact, and he concludes that he needs to correct the problem by increasing the golfer's torque values. He believes that by increasing the golfer's torque values, that the golfer will be able to "corner" better after impact, which can potentially direct the club more inside-left post-impact. However, his excessive in-to-out clubhead path is happening pre-impact, and he does not consider other causes that can cause that problem eg. excessive torso-pelvic separation where the pelvis out-runs the upper torso and arms, or a body/arm synchrony problem where the upper torso is rotating faster than the arms.
Then, to solve the problem of how to increase the golfer's torque, he starts off by testing for leg dominance. That test is very simplistic and he gets the golfer to swing on one leg and if the clubhead speeds is faster when swinging on the lead leg, he concludes that he must work on the lead leg in order to increase torque values. That makes no sense to me because one cannot use the right-sided lateral pelvic rotator muscles during that test. Also, when balancing on only one leg (either leg), I think that it will be upper torso rotational speed that will determine arm speed, and therefore clubhead speed and it does not necessarily correlate with the efficiency of each leg in contributing to the generation of horizontal GRFs when two feet are grounded. Finally, I think that the upper torso/arms cannot efficiently rotate fast when solely balancing on the trail foot because one will become unbalanced and topple over if one tried to rotate the arms faster.
By the way, SL even admits that his leg dominance test is empirical and not based on "science".
Note that SL does not work on increasing the efficiency of the golfer's counterclockwise pelvic rotation by increasing the ability of the right-sided lateral pelvic rotator muscles to induce a better counterclockwise pelvic rotation. That would require the golfer to maintain pressure-loading of the the right leg/foot between P4 => P5 and it would require avoiding any increase of the horizontal GRF under the right foot, which can cause the right buttock to prematurely leave the tush line.
Jeff.
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Post by dubiousgolfer on Jun 10, 2021 11:57:21 GMT -5
The other thing I noted doing that rear-one legged drill is that my range of rear hip internal rotation was much less than my degree of external lead hip rotation using the front-one legged drill. Basically I was restricted in the rotation of my pelvis and upper torso, reducing my hand path in the backswing (meaning a reduced capability to do 'work' on the club in the downswing).
DG
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Post by dubiousgolfer on Jun 10, 2021 12:05:03 GMT -5
I agree with MA that all pro golfers move their pelvis toward their lead foot between P4 => P7 - irrespective of whether they are rear-post, center-post or front-post golfers at P4. Front-post golfers already have their pelvis forward at P4, but a rear-post golfer has to have a left-lateral pelvic shift movement happening between P4 => P7 in order to get the pelvis more forward (targetward) by impact. Having the pelvis forward at impact does not necessarily correlate with COP measurements at impact, because some pro golfers will have a reverse-foot pattern of COP measurement at impact while other pro golfers will have a front-foot pattern of COP measurement at impact. MA does not care about the actual value of the COP measurement at impact and he is mainly concerned with the Swing Catalyst's horizontal torque, rotary torque and vertical force measurements happening in the early-mid downswing. A rear-post golfer, who uses a "glider" pattern will likely have a high horizontal torque value happening very early in the downswing between P4 => P4.5. A center-post golfer, who uses a "spinner" pattern, will likely have a high rotary torque value peaking at P5. A front-post golfer, who uses a "launcher" pattern, will likely have a high vertical force value peaking between P5.5 => P6. The actual COP measurements at impact are not relevant to MA's classification system. Here is Sasho's graph showing the results of his study of pro golfers, which showed a very high correlation between clubhead speed and a high COP measurement under the lead foot at shaft vertical. Note that he found a high correlation R value of 0.91. Scott Lynn repeated the study on pro golfers and found a very low correlation coefficient value of 0.33 at shaft vertical - see graph below. I trust Scott Lynn's results, and not Sasho's results. If you view Scott Lynn's presentation in session number 5, you can learn a lot. Jeff.
I sent an email to SMK about the differences in the graphs and this is his reply: "I don’t know much about Scott’s data, but I’m not surprised by the results. I’ve plotted this graph from about 5 different data sets over the years. Correlations have ranged from about .65 to .91. The graph below was the highest I’ve seen. My data has been from a heterogenous group of golfers. From the graph you can see that I had players swinging below 80 mph. Scott’s data is all PGA Tour players. It is less likely to find high correlations in a homogenous sample. There would be little correlation between height and points per game in the NBA. Yet, we know height is really important in basketball. Each of the dots in my graph represents the average of many swings by each participant. I’m not sure how many swings Scott measured per dot. Hope that helps." DG
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Post by imperfectgolfer on Jun 10, 2021 14:19:48 GMT -5
DG,
Sasho's answer makes no sense to me.
Look at the golfers in Sasho's study that had clubhead speeds >100mph, which would represent a homogenous group in terms of clubhead speed. His graph would show that his homogenous group of golfers (>100mph clubhead speed) has a high R value while Scott Lynch's homogenous group of golfers (>100 mph clubhead speed) has a lower R value.
Sasho wrote-: "It is less likely to find high correlations in a homogenous sample. There would be little correlation between height and points per game in the NBA. Yet, we know height is really important in basketball."
Why would it be less likely to find a strong correlation in a homogenous group if the factor being studied is highly significant from a causality perspective?
Also, height is obviously important in basketball, but it is not the major causality factor in terms of scoring because nearly all the players are very tall.
Jeff.
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Post by dubiousgolfer on Jun 10, 2021 21:50:32 GMT -5
I wonder why none of the golf scientists have even bothered to look at the path of the left shoulder joint in the downswing as a possible indicator of high angular velocity of club between P6-P7. Couldn't the curvature of the shoulder and hand path relative to the position of the golf clubs COM in the downswing have a major impact on the magnitude of the 'In Plane MOF'? Timing the extension of the lead leg (which will also cause an increasing vertical GRF) can help create a more curved shoulder & hand path that could change the magnitude and direction of the 'In Plane Normal force' (and therefore the 'In Plane MOF'). I'm finding it hard to accept Dr Kwon's theories about vertical grf forces creating 'body COM pivoting moments' to get more torque via the body in the frontal plane and into the clubhead. If you look at the Lexi Thompson image, one can easily visualise how the path of the lead shoulder might be an indicator of a 'Normal' force that might increase the MOF and angular velocity of the club. Basically , Lexi is not allowing the COM of the club to catch up and align itself with the tail end of the 'Normal Force' vector and that helps maintain a greater 'moment arm'. DG PS . Here is an image of TW's lead shoulder path that Dr Mann has previously posted . I can imagine some 'horizontal (including braking)/rotary torque /vertical' ground reaction forces being created while he uses muscular contractions to move that 'shoulder/left arm/left hand' in some optimal path to 'time/maximise' the effect a resulting MOF and create peak angular velocity of the club by impact. One thing that must be understood by ground reaction forces is that they have a net effect on the COM of the golfer (as per Newton's laws which are applied to bodies that are idealised as single point masses) and cannot be directly associated with moving body segments .
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Post by imperfectgolfer on Jun 11, 2021 18:05:15 GMT -5
DG,
I think that they are aware that increasing the vertical GRF component will elevate the left shoulder socket and affect the MOF and they do believe that timing when the vertical force should be maximised is very important. They provide examples when the timing is sub-optimal, and they recommend an alternative (more optimal) timing.
Jeff.
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Post by dubiousgolfer on Jun 11, 2021 18:56:27 GMT -5
I found some more videos posted by Peter Croker on the Golfwrx forum (copy of his post is below). A detailed analysis of various golfer swings , how they addressed and fixed any issues is shown under some of the videos. forums.golfwrx.com/topic/1121974-bioswing-dynamicsea-tischlermike-adamsmark-hackett/------------------------------------ From Peter Croker: BioSwing Dynamics works! Just had Mike Adams, Dr Scott Lynn, and Terry Rowles deliver a 5-Day Teach the Teacher School to an enthusiastic Group of Australian PGA Professionals at Moonah Links Golf Club here on the Mornington Peninsula, Victoria, Australia. In reading the prior posts here, I can only endorse what Mike, EA, and their BioSwing Dynamics Team have put together here. As students of golf we all need regular coaching and therefore there is no excuse for trying to figure it all out by yourself when the wheels fall off - Go to a mechanic - a BioSwing Dynamics Mechanic (Coach) and get a re-alignment and repair or replace any damaged parts! The Aussie School at Moonah Links 18 professionals and 7 amateurs attended and the least increase in clubhead speed for a 7 iron and or driver was 5 mph. When this increase in power for every student who first tests to find their own best swing can be achieved for each student who attended, this is a significant result and in my time as a player and coach is a first. My own experience saw a 10 mph increase in clubhead speed for the driver - thought there might be some interest in seeing how Mike and Terry and our Aussie Pros deliver such results for their students DENNISE HUTTON lesson with MIKE ADAMS and RICHARD BLAKE - MOONAH LINKS - Nov 8, 2017 vimeo.com/242932420/c924a0b217CHRIS BECKETT lesson with MIKE ADAMS vimeo.com/242951008/96e30d23e8 PETER CROKER Driver lesson with MIKE ADAMS and TIM WOODS - Nov 10, 2017, at MOONAH LINKS vimeo.com/242956554/4b9c4b3496BEN CROKER Driver Lesson with MIKE ADAMS and TERRY ROWLES vimeo.com/244956643/fd7fbca6ccBEN CROKER lesson with MIKE ADAMS 0 Right Palm Open Release Drill +Diagonal Closed Uphill Drill vimeo.com/244957345/fa67a7a818JONATHAN HICKMAN lesson with MIKE ADAMS and TERRY ROWLES with DRIVER and 3 WOOD Nov 10, 2017 vimeo.com/242496029/22e696ac19 IAN PASSWELL lesson on SWINGCATLYST with MIKE ADAMS vimeo.com/244953449/d28a95cd1f ---------------------------------------- DG
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Post by imperfectgolfer on Jun 12, 2021 17:09:21 GMT -5
DG- I found those golf instructional lessons interesting in the sense that MA only focused on a few instructional points eg. getting the pelvis to rotate faster or in the last example telling the golfer to move his arms faster. In the last golfer - Ian Passwell - he instructed the golfer to push the shaft more leftwards after impact. That golfer had an on-top trail hand grip pattern. It is interesting that the first golfer - Dennise Hutton - had such a strong trail hand and strong lead hand grip, even though her body/arms motions did not look different to the other golfers. I suspect that he chose her trail hand grip position based on his screening test. The more I study this "trail hand grip" screening test, the more that I think that it is unscientific. I am increasingly of the opinion that most golfers should not use an on-top trail hand grip associated with a punch elbow motion during the downswing. I have been looking at many pro golfers who use an on-top trail hand grip at address and I have noted that some of them use a pitch elbow motion (where the trail elbow drops below the lead elbow between P4 => P6) during their downswing even though they use an on-top type of backswing action (where the trail elbow remains higher than the lead elbow throughout most of the backswing action). Here are a two examples. Colin Montgomerie Note how he drops his trail elbow well below his lead elbow in his early downswing and that he shallows the clubshaft. Note that his right forearm is significantly supinated at P6. Note that his lead arm is extended away from his body at P6.
Matthew Fitzpatrick Note how he drops his trail elbow well below his lead elbow in his early downswing and that he shallows the clubshaft. Note that his right forearm is significantly supinated at P6. Note that his lead arm is extended away from his body at P6. There are some on-top pro golfers who use a punch elbow motion between P4 => P6 and they look different at P6.
Here is an example featuring Patrick Reed.
Note that his right forearm is less supinated at P5.5 (image 1) and P6 (image 2) and that the trail hand looks more on-top. Note that the lead arm is more vertical at P6.
Look at what happens after P6 in Patrick Reed's golf swing action. Note how his trail wrist fully straightens through impact and that the clubshaft bypasses the stalled lead arm producing a non-DH hand release action. Note how much his trail wrist straightens through impact and his trail palm even loses contact with PP#1 (located over the base of his lead thumb) and his club handle post-impact. Note that he "runs-out-of-right arm" soon after impact and that results in trail forearm pronation that excessively rolls the club handle causing a high clubface ROC between P7 => P7.2+.
I guess that Terry Rowles would argue that a higher clubface ROC through the immediate impact zone between P7 => P7.2 does not correlate with a decreased ball flight accuracy, but I am sceptical about that claim. I have seen Patrick Reed hook the ball left on a number of occasions when watching him on TV and I wonder whether his non-DH hand release action is a major causal factor. Jeff.
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Post by imperfectgolfer on Jun 12, 2021 18:17:05 GMT -5
I was looking again at the 3 Instagram videos that DG posted in page 1 of this thread where Terry Rowles discusses how a golfer should find the best trail hand grip. He demonstrates the "trail grip" screening test and he then states that if you are an "on-top" golfer that you are an open-face golfer who must use a closing action to square the clubface by impact. He then implies that a closing action is secondary to fully straightening the right arm which will pronate the trail forearm and roll the trail hand over the lead hand through impact. By contrast, he recommends that if you test out as an "under" golfer, that you are a closed face golfer who needs to hold-off the closing action in the later downswing. Here are capture images of his video demonstration.
The left-sided image is from his "under" trail grip video. Note how he is flipping the club through impact with his hand rolled-under the club handle.
The right-sided image is from his "on-top" video. Note how he is flipping the club through impact with his trail hand rolled-over the club handle.
I personally do not favor playing golf where the right hand tries to square the clubface by impact in this flipping manner. I much prefer using a TGM swinging action where the lead arm/hand controls the clubface and where the golfer uses a DH-hand release action through impact.
Jeff.
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Post by dubiousgolfer on Jun 12, 2021 20:51:54 GMT -5
I tried an 'On-Top' trail hand grip today because I'm a 'SIDE-COVER' golfer and was striking low hooks (which is rare for me because my bad strikes are usually pushes and push slices).
DG
On a less serious note , I found this video below which I thought was quite funny (trying to use ground reaction forces).
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Post by dubiousgolfer on Jun 13, 2021 7:51:24 GMT -5
I found the timing in the production of 'gliding/spinning/launching ground forces quite interesting and probably means that whatever forces are being applied via the hands must happen early enough to have an effect on the clubhead angular velocity before impact. Maybe trying to swing the arms faster automatically produces the peak 'grfs' early enough in the downswing and is an indicator that the golfer is timing his hand forces more optimally. DG
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Post by imperfectgolfer on Jun 13, 2021 9:34:08 GMT -5
I found the timing in the production of 'gliding/spinning/launching ground forces quite interesting and probably means that whatever forces are being applied via the hands must happen early enough to have an effect on the clubhead angular velocity before impact. Maybe trying to swing the arms faster automatically produces the peak 'grfs' early enough in the downswing and is an indicator that the golfer is timing his hand forces more optimally. DG I cannot understand your line of reasoning. You seem to be implying that the motion of the arms/hands in the downswing can cause the timing and magnitude of the GRFs in the downswing. I do not believe that this is likely. The gliding force must me produced first in an active pelvic motion happening between P4 => P4.5 - particularly in the subset of golfers who are rear-post golfers. The spinning force happens secondarily and peaks between P4.5 and P5, and it is the most prominent force in spinners (center-post golfers). The launching force peaks at P5 => P5.5 and it is the most prominent GRF in launchers (front-post golfers). All those forces are the result of an active pelvic motion event and they are not simply reactive to the motion of the arms happening between P4 => P5.5. I do recall MA stating that an on-top golfer will be producing more vertical downward force when he pulls his arms steeply downwards between P4 => P6 and he implied that it would increase the vertical force component. That would make sense to me if all on-top golfers were front-post golfers (launchers), but they could be using a center-post or rear-post pattern of pelvic motion. I have never seen any evidence presented that there is a high R correlation value between being an on-top golfer and being a front-post golfer - thereby implying a very strong causality link. Jeff.
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Post by dubiousgolfer on Jun 13, 2021 10:53:00 GMT -5
Dr Mann I have no choice but to reason this way from a purely physics perspective. It's not just the swinging of the arms but other body segments too (as per your mention of the active pelvic motion). 1. Do you think that grfs are creating energy to move the body segments (other than the COM)? Using physics, to increase the body's total energy, work needs to be done to increase its energy (such as external forces by something else pushing on the body). Here is the definition of work : "Work, in physics, measure of energy transfer that occurs when an object is moved over a distance by an external force at least part of which is applied in the direction of the displacement." 2. If the ground is providing the push force , is it moving in the direction of the force? The answer is no - there is no work being done by the ground on the body and there is no energy being transferred to move the body segments that comprise the golf swing. Therefore, by inference the only energy is coming from internal energy of the body and being turned into other forms of energy such as 'kinetic energy' of body segements. The act of moving these segments in some optimal way requires the golfer to generate the ground forces to facilitate the intended movement. If the golfer is swinging 80% of his capability but then decides to swing at 90% , the GRF forces created will change to reflect that intent. DG PS. This is a complex and confusing matter in physics and I do not expect many people to understand the below (even some well renowned golf scientists) unless they are aware of something called the 'First Law Of Thermodynamics' (FLT) . Many physicists use the 'Centre Of Mass' (CM) equation to try and understand energy changes going on without considering the FLT. One can alter that FLT equation and interpret it as following: Change in Internal Chemical Energy In body = Change in the 'Kinetic Energy' of the 'Centre of Mass' of the Body + Change in the 'Kinetic Energy' of the Body Segments + Change In the Temperature Of the Body + Change in the 'Gravitational Potential Energy' between Earth and body The ground reaction forces are not even mentioned above but can be used mathematically to equate the change in 'Kinetic Energy' of the COM of the body.
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Post by utahgolfer on Jun 13, 2021 15:30:33 GMT -5
Jeff, I was referring to session 5 in the ultimate golf lesson seminar. That’s the cream to me. We’ve all taught thing’s earlier in our life we wish could be deleted. The only way to make lesson 5 better is to have a scone and cream while watching it!
Again, saying their measurement screen is not scientific is probably not helpful. Standing alone it is patently worthless. The screen is only useful if it somehow speeds up the teaching and learning process. The screen is a means to an end. And, the end is an a better path direction, face angle, and club head speed.
The outcome science can only be based on that. Does their method speed up overall progress and lead to lower scores? Nothing else matters. Sasho’s graph and correlation has little to do with this. If a given player hits the ball farther with a loaded lead foot at shaft vertical, then that’s all that matters. If he or she doesn’t, then it doesn’t matter. We only continue with what works. It’s an individual player endeavor, not how data points scatter on a graph. Same with the kinetic sequence. We go with what works. If a player does better with a vertical, horizontal, rotational kinetic sequence, then we accept it and continue on. It doesn’t matter what works for anyone else. We just use all we know to help that person. Success is based on improving path, face, and speed.
Same with a drive-hold release. Just because it makes sense and it should work, doesn’t mean it is best for every player. Only when it promotes the best short- and long-term results. The same is true with every conceivable teaching tip.
Using a force plate and Trackman, are used for the same purpose…to speed up the process by taking away some of the guesswork.
It’s easy to see how some advice might improve path, face, and speed, but only work over the short-term. In this case, it is not ultimately what was best for the player. So, it’s important students come in for multiple lessons and make sure everything points to better performance on the course over the long-term.
I applaud any general analysis of golf swing theory. It’s nice to know how things might work and why they might work. This is valuable. But, this is not the primary outcome goal, at least it’s not for MA and TR. Their main goal is quick player progress, regardless of what works for anyone else.
UG
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