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Post by imperfectgolfer on Jul 28, 2019 21:09:51 GMT -5
Jeff.
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Post by dubiousgolfer on Jul 29, 2019 4:58:37 GMT -5
Dr Mann I think I understand Mike Jacobs video although his presentation skills regarding the physics involved is (imho) poor. The basis of what he is saying would make sense if the clubshaft bends as per this diagram below (note how straight the shaft is near the grip end). This diagram shows the bend of the clubshaft (end to end) and is based on a flawed mathematical assumption by Nesbitt which was proven to be inaccurate by some experiments performed by Dave Tutelman. Mike Jacobs and Brian Manzella have based this whole instantaneous 'Alpha/Beta/Gamma' 'force/torque' concept using that diagram as a 'pointer' to what forces are being applied by the hands. But if the mathematics describing the bend of the clubshaft , especially near the grip end , is incorrect then their opinions are also flawed. It's a bit difficult for them to agree with DT's assertions now after marketing/publishing their book and developing 3D modelling software based on incorrect mathematics. DG
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Post by imperfectgolfer on Jul 29, 2019 9:00:18 GMT -5
Dr Mann I think I understand Mike Jacobs video although his presentation skills regarding the physics involved is (imho) poor. The basis of what he is saying would make sense if the clubshaft bends as per this diagram below (note how straight the shaft is near the grip end). This diagram shows the bend of the clubshaft (end to end) and is based on a flawed mathematical assumption by Nesbitt which was proven to be inaccurate by some experiments performed by Dave Tutelman. Mike Jacobs and Brian Manzella have based this whole instantaneous 'Alpha/Beta/Gamma' 'force/torque' concept using that diagram as a 'pointer' to what forces are being applied by the hands. But if the mathematics describing the bend of the clubshaft , especially near the grip end , is incorrect then their opinions are also flawed. It's a bit difficult for them to agree with DT's assertions now after marketing/publishing their book and developing 3D modelling software based on incorrect mathematics. DG I disagree with your opinion that Mike Jacobs opinions regarding alpha, beta and gamma torques/forces has any connection with the mechanical phenomenon of shaft deflection in the later downswing near impact (which is another controversial, but very minor, side-issue). All of his opinions on this issue are derived from Nesbit's theories. Jeff.
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Post by dubiousgolfer on Jul 29, 2019 11:26:51 GMT -5
Dr Mann - yes you are probably correct. Are you saying Nesbitt's theories are wrong or are you saying that Jacobs/BM have just 'cherry-picked' from SN's research (as you inferred in your forum post thread below)? newtongolfinstitute.proboards.com/thread/570/changes-chris-tiger-woods-swing-------------------------------------------- "In this post, I am going to explain 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. For example, both BM and RF have stated, that when it comes to the topic of alpha, beta and gamma torques, that they have based their golf teaching philosophy on the scientific research performed by Steve Nesbit. Here is a link to Steve Nesbit's research article that is based on a study of 84 amateur golfers. www.motionanalysis.com/pdf/2005_nesbit.pdf"In that study, SN stated that he was studying those 84 amateur golfers so that he could "completely characterize the 3D kinetics and kinematics of the golf swing". He expressed his study's findings in terms of alpha, beta and gamma torques, and like a "true scientist" he simply reported his findings in his article. He found a great variation in alpha, beta and gamma torques manifested by those 84 golfers, and he didn't state in his research article that a specific/single pattern was optimum. However, both BM and RF have selectively chosen certain patterns that some of those 84 golfers manifested and arbitrarily stated that it represented a scientifically-validated way to perform a golf swing. That's obviously not being scientific because SN didn't make that irrational/unscientific claim in his article, and what BM and RF are doing is selectively misinterpreting (or misrepresenting) SN's article to arbitrarily justify their personal golf teaching philosophy. I will demonstrate how they have repeatedly misrepresented SN's study to justify their biased personal approach to teaching the golf swing." ----------------------- I'm finding Gamma Torque difficult to understand . Is 'GAMMA Torque' a 'Twistaway' move because when Jacobs and BM demonstrate it on their videos they are always rotating their forearms at the same time ? I've always thought a forearm rotation when there is a PA3 angle is equivalent to a 'Beta Torque'? DG
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Post by imperfectgolfer on Jul 29, 2019 16:41:18 GMT -5
Dr Mann - yes you are probably correct. Are you saying Nesbitt's theories are wrong or are you saying that Jacobs/BM have just 'cherry-picked' from SN's research (as you inferred in your forum post thread below)? newtongolfinstitute.proboards.com/thread/570/changes-chris-tiger-woods-swing-------------------------------------------- "In this post, I am going to explain 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. For example, both BM and RF have stated, that when it comes to the topic of alpha, beta and gamma torques, that they have based their golf teaching philosophy on the scientific research performed by Steve Nesbit. Here is a link to Steve Nesbit's research article that is based on a study of 84 amateur golfers. www.motionanalysis.com/pdf/2005_nesbit.pdf"In that study, SN stated that he was studying those 84 amateur golfers so that he could "completely characterize the 3D kinetics and kinematics of the golf swing". He expressed his study's findings in terms of alpha, beta and gamma torques, and like a "true scientist" he simply reported his findings in his article. He found a great variation in alpha, beta and gamma torques manifested by those 84 golfers, and he didn't state in his research article that a specific/single pattern was optimum. However, both BM and RF have selectively chosen certain patterns that some of those 84 golfers manifested and arbitrarily stated that it represented a scientifically-validated way to perform a golf swing. That's obviously not being scientific because SN didn't make that irrational/unscientific claim in his article, and what BM and RF are doing is selectively misinterpreting (or misrepresenting) SN's article to arbitrarily justify their personal golf teaching philosophy. I will demonstrate how they have repeatedly misrepresented SN's study to justify their biased personal approach to teaching the golf swing." ----------------------- I'm finding Gamma Torque difficult to understand . Is 'GAMMA Torque' a 'Twistaway' move because when Jacobs and BM demonstrate it on their videos they are always rotating their forearms at the same time ? I've always thought a forearm rotation when there is a PA3 angle is equivalent to a 'Beta Torque'? DG I think that Nesbit's theories have no practical correlation in terms of the practical biomechanical movements that a golfer must perform in order to enact a golf swing. Nesbit used inverse dynamics to theoretically calculate what the forces/torques must exist (in the alpha, beta and gamma framework) to create an observed hand arc path and observed pattern of club motion. However, he seemingly knows nothing about what specific biomechanical motions are practically needed to create a specific hub path and specific club motional pattern. MJ/BM are even worse - because they "cherrypick" his opinions and often misinterpret them. Twistaway can create gamma torque (even if the clubshaft is stationary), but left forearm supination (during a PA#3 release action)is also a gamma torque phenomenon happening while the clubshaft is in constant motion. Jeff.
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Post by dubiousgolfer on Jul 29, 2019 17:51:31 GMT -5
Many thanks Dr Mann
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