|
Post by dubiousgolfer on Mar 18, 2019 10:10:32 GMT -5
Dr Mann
I've noticed that there is a new book published by M Jacobs in association with Steven Nesbit .
Is this a book you might be reviewing in the near future?
DB
|
|
|
Post by imperfectgolfer on Mar 19, 2019 0:24:40 GMT -5
DB,
I may purchase that book later this year if they produce a cheaper Kindle edition.
Then, I will decide whether to review it.
Jeff.
|
|
|
Post by dubiousgolfer on Apr 24, 2019 12:55:10 GMT -5
DB, I may purchase that book later this year if they produce a cheaper Kindle edition. Then, I will decide whether to review it. Jeff. Dr Mann- understand you may not be reviewing Jacobs book until it has been produced at a cheaper price (I won't be buying it !!!). I have been looking at Michael Jacobs You Tube videos and I am finding it difficult to find anything new in what he says. An example are these video below (Jacobs and Nesbit) where I couldn't find anything original regarding hand path and release (ie. similar to 'Endless Belt', Law Of The Flail, D'Alembert principle). I also exchanged some emails with Dave Tutelman regarding 'Jacobs' opinions and he was also doubtful about the physics/maths (used by Nesbitt) to describe the flexing of the clubshaft into impact , which has been used by Jacobs/Manzella to suggest a positive Alpha Torque requirement in the late downswing . I think you have reviewed this topic before in some detail on this website (:http://newtongolfinstitute.proboards.com/thread/570/changes-chris-tiger-woods-swing). "why I believe that Brian Manzella (BM) and Richard Franklin (RF) are manifesting a pseudo-scientific (junk science) approach to teaching the golf swing when they base their golf instructional teaching on their misinterpretation (or misrepresentation) of the scientific research performed by golf researchers " The whole argument between 2 groups of golf scientists is mentioned in Tutleman's website below: www.tutelman.com/golf/swing/nesbitKwon1.phpWhat I find confusing is why the golf scientists are so dismissive of the qualitative nature of TGM? When I look on the internet for a definition of 'Qualitative Research' it says the following: "Qualitative Research is primarily exploratory research. It is used to gain an understanding of underlying reasons, opinions, and motivations. It provides insights into the problem or helps to develop ideas or hypotheses for potential quantitative research" So isn't the quantitative data (gathered) dependent on the qualitative assumptions? And if the current modelling of the golf swing is based on incorrect qualitative opinions , won't the quantitative data being measured be biased towards an 'opinion'? I cannot see how 'quantitative data' can be used to build a qualitative opinion of a specific golf swing unless the modelling being used can also perfectly represent the movements of a specific human body. DB
|
|
|
Post by imperfectgolfer on May 1, 2019 9:34:01 GMT -5
DB, You wrote-: " What I find confusing is why the golf scientists are so dismissive of the qualitative nature of TGM? When I look on the internet for a definition of 'Qualitative Research' it says the following:
"Qualitative Research is primarily exploratory research. It is used to gain an understanding of underlying reasons, opinions, and motivations. It provides insights into the problem or helps to develop ideas or hypotheses for potential quantitative research"
So isn't the quantitative data (gathered) dependent on the qualitative assumptions? And if the current modelling of the golf swing is based on incorrect qualitative opinions , won't the quantitative data being measured be biased towards an 'opinion'?
I cannot see how 'quantitative data' can be used to build a qualitative opinion of a specific golf swing unless the modelling being used can also perfectly represent the movements of a specific human body."
I think that golf researchers are severely hampered by not taking TGM mechanics into proper account. For example, Steve Nesbit assumes that the right arm is applying a positive torque during the PA#2 release phase between P5.5 and P6.5+, but I do not think that it is happening in a "pure" TGM swinging action where the right palm is not actively pushing against the aft side of the club handle. I also suspect that Sasho MacKenzie's hand couple ideology is not compatible with a TGM swinging action. Both of those golf researchers should design golf studies to actually measure the amount of push-pressure being exerted by the right palm against PP#1 and PP#3 during the entire downswing - in order to determine whether the results of their golf research study is compatible with their hypothesis (which is based on theoretical reasoning and inverse dynamics modelling) or whether it is more compatible with TGM mechanics.
Jeff.
|
|
|
Post by dubiousgolfer on May 3, 2019 8:10:58 GMT -5
After reading the ' Introduction' to the research article 'Force and Moment Exerted By Each Hand On An Instrumented Golf Club' (Sekiya Koike), I now understand what a 'Closed Loop Problem' is and why Jacobs research is probably flawed . If Jacobs has been using Nesbit's 'inverse dynamics' research to claim positive alpha torque into impact , then he must be claiming to have resolved the 'closed loop problem ' . Koike says there are infinite sets of forces and moments (ie. torques) that can cause the same motion. Therefore Jacobs must be implying that he has now found a generic specific set of forces and torques to explain positive Alpha Torque into impact. Koike goes further by saying it is impossible to work out the forces and torques exerted by the hands on the grip handle using inverse dynamics with only visual information. DB
|
|
|
Post by imperfectgolfer on May 3, 2019 8:58:04 GMT -5
After reading the ' Introduction' to the research article 'Force and Moment Exerted By Each Hand On An Instrumented Golf Club' (Sekiya Koike), I now understand what a 'Closed Loop Problem' is and why Jacobs research is probably flawed . If Jacobs has been using Nesbit's 'inverse dynamics' research to claim positive alpha torque into impact , then he must be claiming to have resolved the 'closed loop problem ' . Koike says there are infinite sets of forces and moments (ie. torques) that can cause the same motion. Therefore Jacobs must be implying that he has now found a generic specific set of forces and torques to explain positive Alpha Torque into impact. Koike goes further by saying it is impossible to work out the forces and torques exerted by the hands on the grip handle using inverse dynamics with only visual information. DB I agree with your opinion that it is impossible to accurately calculate the forces/torques being applied to the grip using inverse dynamic modelling - because there are many practical possibilities in a "real life" golf swing action. I would take the argument further and assert that Koike's measurement system is also flawed because he uses a split-hand grip where he presumes that the right hand is only pushing against the shaft when it could be pushing against PP#1 (located over the base of the left thumb). I would need to see the results of many more research studies using an instrumented grip before I take the hand-couple theory seriously. I would also need to see how Sasho's hand-couple theory affects the way a golfer performs the downswing from a biomechanical perspective, and I have never seen Sasho comment on this issue. Jeff.
|
|
|
Post by dubiousgolfer on Jun 5, 2020 19:09:14 GMT -5
Looks like the arguments/debates between Sasho Mackenzie and 'Mike Jacobs 3d' product is getting a bit tetchy. I thought I'd post it in case anyone is interested in this ongoing debate between the two golf scientific camps. Needless to say , I found it 'challenging' to understand both videos but I had enough COV isolation time to persevere. SMK video first vimeo.com/sashomackenzieResponse by Mike Jacobs After spending several hours going through each video, SMK has pointed out errors in Jacobs 3d product , but also Jacobs has found errors in SMK's interpretation of his product. SMK is correct that the naming convention of Jacobs 3D product for alpha, beta, gamma torques is NOT like Nesbit's research articles. Also imho (although I may be wrong), some of SMK's analysis could be flawed because he may have got confused with the convention that Jacobs uses for alpha, beta and gamma FORCES (and who can blame him!). For example Jacobs 3D is using an alpha 'force' direction that is in the plane of rotation of a beta 'torque'. Also a beta 'force' that is in the plane of rotation of an alpha 'torque', then a gamma 'force' that pulls away from the COM of the club towards the butt end (but not in any named torque rotational plane). The COM of the club is not in line with the shaft therefore theoretically a gamma force pull along the shaft will cause an MOF on the COM to align with that force and rotate it in some 3D plane , but Mike Jacobs is probably correct to say the 'rotational' effects will be small. Nevertheless, SMK is correct to say that it is an incomplete piece of kinetics not used in Jacobs 3d product. DG PS. The force/torque conventions that Mike Jacobs uses in his product is explained in this video below
|
|
|
Post by imperfectgolfer on Jun 6, 2020 9:31:49 GMT -5
I am so happy that I do not understand what Sasho and Mike Jacobs are saying - because I don't have to waste time trying to correctly analyse their irrelevant physics-based arguments.
Jeff.
|
|