Palmar flexing the left wrist at the start of the downswing

[imperfectgolfer]

Jul 21, 2020 10:53:15 GMT -5 dubiousgolfer said:

I posed the question 2 days ago on one of their You-Tube videos (no reply yet).

DG

HackMotion will not discuss the problem related to a low sampling rate. They simply claim that their graphs are error-free!

Interestingly, I remember asking Michael Neff how he proved that his GEARS 3D system (operating at 450 Hz) was getting accurate results, and he stated that he used a Phantom camera as a check. Even though a Phantom camera only produces 2D images, it can operate at a very high sampling frequency of 10,000 - 100,000 frames/second.

I actually think that this Phantom camera swing video at ~4,000 frames/second is much more accurate than a 3D system operating at 100-240 samples/second.





Here are capture images from the video showing the lead wrist's motion between P7 and P7.2.





It is obviously impossible to quantify the amount of "left wrist extending" happening post-impact between P7 and P7.2, but it is obvious that his lead wrist is not rapidly-massively extending during that time period. Stop the video at the 0:56 minute time point and you will note that his clubshaft is straight-line-aligned with his left forearm.


Jeff.

[dubiousgolfer]

Dr Mann

HackMotion could create those detailed graphs by altering the timing of the sampling over many repeated golf swings. Such that a measurement was taken slightly earlier or later post impact for the first few feet, but one would have to make a huge assumption that each swing was identical.

However , if those detailed graphs were being produced using a single swing , then I'd question its accuracy for a 100 Hz sampling rate.

I find the Phantom camera videos truly amazing.

DG

[dubiousgolfer]

Jul 1, 2020 10:21:00 GMT -5 dubiousgolfer said:

Hi UG

Clubface Closure Velocity or ROC dependency is given below in Phil Cheethams dissertation . Not sure if it will assist you.



DG

PS. Whatever the golfer does whether a large or small PA3 angle , the lie angle still determines the 'functional plane' the clubshaft needs to be swung on from P6- P7.

I suspect if golfer has a small PA3 angle (for some Swing Plane Velocity and lie angle) then CCV might be determined by the  HTV part of that equation (level of active forearm rotation).  I suspect if there is a large PA3 angle (ie. SPV and lie angle unchanged), the MOI of the club around the longitudinal axis of the lead arm will be greater and the  HTV 'likely' smaller (but that would be dependent on the strength of the golfer).

There is no mention of other characteristics of the swing (ie. angle of attack , etc ) that affects the ROC . If there were , I would expect the maths to be ultra complex to determine cause and effect of ROC 

For the sake of accuracy I thought I'd better add Phil Cheetham's email response regarding the above diagram and ROC equation in his dissertation.

"The theta in the equation is really the angle of the club shaft at impact (not the same as the lie angle), not just the lie angle."

DG

[dubiousgolfer]

Dr Mann

It's just occurred to me that Dr Kwon's diagram below and your diagram (to the right Kelly Oride's images)  regarding Drive Holding means that the centre of rotation of the clubhead must move from that impact point (above the mid-point of the hands) to nearer the lead shoulder joint in 4/1000 sec (club ball impact period).

Am I correct?





DG

[imperfectgolfer]

DG,

I don't know why you would believe that this theoretical "COR-phenomenon" must happen during the impact interval rather than over a longer time period between P6 => P7.

Jeff.

[dubiousgolfer]

Yes, on reflection , that COR shown by the green line on Dr Kwon's diagram is just a mathematical calculation and a 'virtual' swing centre.

DG

[imperfectgolfer]

Jon Sinclair has argued that the lead wrist of pro golfers routinely moves rapid-and-massively towards "lead wrist extending" through impact, and he has "smoothed" 3D graphs that show that phenomenon.

Here is Phil Cheetham's 3D graph representing a generic pro golfer's lead wrist behaviour in the downswing and through impact.

Note that the lead wrist is extended at P4 and that it moves towards flexion in the later downswing reaching its peak flexion value just before impact. Then it moves in the direction of "lead wrist extending" through impact. There is a plateau in the lead wrist flexion graph immediately post-impact, which Jon Sinclair claims is due to ball collision.

Now, consider J B Holmes 3D graph showing the angular velocity of his lead wrist flexion-extension phenomenon - presented by Phil Cheetham - which I copied from Michael Finney's zoom 2 online conference.

I am presuming that flexion is above the zero line, and extension below the zero line, in my following interpretation of the lead wrist flexion-extension velocity graph.

Note that his lead wrist starts flexing in the later downswing and it only reaches its peak flexion angular velocity value post-impact before it subsequently moves in the direction of "left wrist extending".  At the time of his peak lead wrist flexion phenomenon, which happens after impact, the lead wrist is flexing at >400 degrees/ second (according to that Phil Cheetham-sourced graph). This contradicts Jon Sinclair's assertion that the lead wrist is always moving towards "lead wrist extending" through impact in all pro golfers.

Here is a birds-eye view swing video of J B Holmes's driver swing.

Here are capture images from the birds-eye view swing video of JB Holmes driver swing.

Image 1 is at P6.7, image 2 is just through impact at ~P7.1 and image 3 is at P7.4.

J B Holmes uses a strong left hand grip so that when he approaches impact, the ulnar border of his left hand faces the target while the back of his lead wrist/hand is angled more towards the ball-target line (image 1). However, note that his lead wrist is slightly bowed at P6.7 and overtly bowed at P7.1 where the back of his lead hand is facing more towards the target due to the counterclockwise rotation of his lead wrist/hand happening between P6.7 and P7.1. Note that his lead wrist still looks bowed at P7.4. Note that there is concordance between these capture images and Cheetham's 3D graph showing lead wrist bowing through impact into the early followthrough.

J B Holmes is therefore an example of a golfer who does not rapidly-and-massively move the lead wrist in the direction of "lead wrist extending" through impact, and his lead wrist flexion velocity seemingly reaches its peak value after impact.

Jeff.

[jon]

I have been capturing data on the AMM System for 15 years. I would consider myself an expert in both capturing and interpreting the data. I have have been a student of Dr. Phil Cheetham for that entire time and I believe he would agree I am one of the few that would be at the top of his list when it comes to his system. I have one of the best data bases of top Tour Professionals in the world. I have had and still have almost every capture device there is on the market. I have done intense research in how they all work and capture data. Even the ones I do not own I have made a point to understand the technology and how it works. I have personally helped 3 manufactures develop their 3D systems.

I applaud Dr. Mann’s enthusiasm and passion for the game. In his quest to to explain his DH release I actually tried to help him. He unfortunately did not like the answer he received. This thread has my name all over it and there are so many inconsistencies, misrepresentations and basic misunderstandings that it would take another 5 page thread to correct all of them. I felt the need to at least post and correct the most egregious error that was made. Dr. Mann’s basic idea of a DH release being a low ROC is correct as I told him. The look he is presenting with all the 2D videos is what I would see in a low ROC release. It is his thinking on how the wrist actually moves his where I think he gets confused. He wants to validate a 3D motion using 2D pictures.  This is fraught with errors and misconceptions.

In Dr Mann’s haste to prove that a player does not move toward extension before impact he has made a basic error. IMO he should have done the leg work in understanding the different systems and how they work. He compares two different ways of capturing and says it proves a point. At the very least he should have consulted experts about how to read the graphs and what each one is actually measuring. Although I saw several mistakes made in this thread reading the graphs the one that has the most significance is the one that is posted about JB Holmes. Dr. Mann uses a video done by Michael Finney where Dr. Cheetham pulls up JB Holms swing. Dr. Mann states that JB Holmes is going in to Flexion at 400d/s at impact. This statement is completely backwards. In that graph shown by Dr. Cheetham extension velocity is in the positive direction above the line. This means JB was moving at 400d/s at impact toward extension. This detail blows up his hole argument that the shaft could stay in line with the lead forearm for any meaningful amount of time. He first told me this phenomenon happened from P7 to P7.4. He appears to have lowered that to P7 to P7.2. Either way it will not do it.  

First imagine; Swinging a club slowly where you would be flexing your lead wrist through impact. Maybe hold a club and do it so you can feel what is going on. Then ask yourself “Is this really what I would want to happen while trying to hit a ball as far as possible?”. Or would you want to do it like JB Holms and allow that wrist to move toward extension at 400d/s knocking the stuffing out of the ball?  I think you will all see the error in this thought. Then also imagine your wrist is moving at 400d/s toward extension. Do you think in your wildest dreams your shaft would stay pointed at your lead forearm? Do you think your wrist would suddenly stop and hold that position with a club effectively weighing 100 lbs at impact? Yes it is noise after impact!

I will leave with a graph of the slowest ROC player I have in my data base. This is a DH release to the MAX. You will notice his wrist extension velocity is 877.7d/s at impact.

I wish you all well and I hope this clears up at least some of the confusion presented in this thread.

[jon]

This is the lowest roc player I have in the data base.

Attachments:

[dubiousgolfer]

Aug 18, 2020 16:23:26 GMT -5 jon said:

This is the lowest roc player I have in the data base.

Hi Jon 

I do have a question about how rapid lead wrist extension equates to Choi's latest research below (that Dr Sasho MacKenzie posted on his twitter account)?

They used an instrumented grip to measure forces (and estimated hand couples)  and found the following (see graphs F , M and Q)?  Doesn't that suggest that the right and left hand are trying to prevent rapid extension into impact.?





DG

PS. I also forgot to mention Robert Grober's article (see .pdf link below) which seems to suggest that golfers might be actively applying negative torque to increase the clubhead path radius through impact so that it tracks the target line more (ie. less in-out-in ).

arxiv.org/pdf/2006.11778.pdf

[jon]

Dr. Mann,

This sure sounds like a deflection. You are struggling to see the truth you yourself posted and misinterpreted.

Yes! All of the evidence I have seen plus all the work I have done with Dr. MacKenzie suggests the trail hand is retarding the club. I have put 5+ years of time in to this question as well. This does not change what is happening. Just think how fast the lead wrist would extend if the trail hand could keep up!

Lets continue the fun! Lets stay on the topic. Look at these two swings. Both the same DH player with the same intent in the swings. What is the difference? It will be easy to guess. The answer however will not progress your narrative.

[jon]

[imperfectgolfer]

Aug 19, 2020 13:00:56 GMT -5 jon said:

Dr. Mann,

This sure sounds like a deflection. You are struggling to see the truth you yourself posted and misinterpreted.

Yes! All of the evidence I have seen plus all the work I have done with Dr. MacKenzie suggests the trail hand is retarding the club. I have put 5+ years of time in to this question as well. This does not change what is happening. Just think how fast the lead wrist would extend if the trail hand could keep up!

Lets continue the fun! Lets stay on the topic. Look at these two swings. Both the same DH player with the same intent in the swings. What is the difference? It will be easy to guess. The answer however will not progress your narrative.

Jon,

You seem to be confusing another forum member (Dubious Golfer) with me (imperfectgolfer). If you respond to another forum member, then you should routinely address your post to that person, and not me.

You have vigorously criticised me in your original post in this forum and now you have even stated that I am trying to deflect attention because you believe that I am struggling to see the truth. You are free to harbor those wrongheaded beliefs. At this point, I will only state that I am working on a response to your original post, but it will take me many days to complete my response because it will probably be between 20-50 letter-sized pages in length. In particular, I am going to explain in great detail why I believe that your 3D work output on the full golf swing is worthless and why I believe that it has no practical value in helping golfers better perform a full golf swing action. Stay tuned!

Jeff.

[dubiousgolfer]

Aug 19, 2020 13:00:56 GMT -5 jon said:

Dr. Mann,

This sure sounds like a deflection. You are struggling to see the truth you yourself posted and misinterpreted.

Yes! All of the evidence I have seen plus all the work I have done with Dr. MacKenzie suggests the trail hand is retarding the club. I have put 5+ years of time in to this question as well. This does not change what is happening. Just think how fast the lead wrist would extend if the trail hand could keep up!

Lets continue the fun! Lets stay on the topic. Look at these two swings. Both the same DH player with the same intent in the swings. What is the difference? It will be easy to guess. The answer however will not progress your narrative.

Hi Jon  - sorry I should have mentioned I wasn't Dr Mann .

So , if we assume that there is no intent for the golfer to retard the club , then doesn't that mean the hands just cannot keep up with the clubs angular speed (that was generated earlier in the downswing)? Which is why there is more forward shaft bend at impact than is expected by eccentric loading alone?

Also , those Choi graphs show negative torque in the left hand too so it doesn't seem to be a retarding effect with just the right hand.

DG

[jon]

Well I keep getting tagged as if Dr. Mann is writing this. It all falls in line with his statements to me. If you would use your real names instead of handles it would be easier to know who is who. It doesn’t matter who wrote it. The facts will remain as I put them up.

Now that I know which Jeff it is it makes me less interested and sorry I ever responded. He is just a professional arguer and has little credibility with me or most everyone one else in the golf world.

Jeff,

You can write a book on what ever you want and it would not be anything I would be interested in. You have already proven yourself to me and about everyone else.

Dr. Mann,

Quit tagging me as if you wrote these things. It wasn’t you that proved yourself wrong by posting incorrectly it was Jeff misreading the graphs. Either way you now know the truth about your DH release. That should be worth at least $500 to St. Jude’s Hospital. You get half price because it wasn’t who you requested it be.

The facts are the facts and you can believe what you want.

Good luck with your journey!