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Post by imperfectgolfer on Oct 7, 2013 11:37:21 GMT -5
See this jeffy forum thread. jeffygolf.com/showthread.php?809-Video-Sasho-MacKenzie-and-Chris-ComoThey are discussing this video presentation by Chris Como and Sasho MacKenzie See - www.youtube.com/watch?v=iuJaSM7KexwWhat is SMK actually saying? I will present my personal interpretation. If you disagree with my personal interpretation, feel free to present a counterargument critiquing my personal interpretation. The main topic is the factors affecting the release of PA#3. Image 1 shows the clubshaft (blue line) below the plane of the hand arc path (red line). SMK is basically saying that if one flattens the clubshaft plane in the early downswing (which requires left forearm pronation) that it will require less force to rotate the left arm about its longitudinal axis in the later downswing (and this represents the release of PA#3). In other words, in terms of physics, SMK states that it lowers the MOI. I prefer to think in biomechanical terms by stating that shallowing the clubshaft causes the left forearm to be more pronated, and that it makes it much easier to actively/muscularly supinate the left forearm in the later downswing. Now when does the M arm torque force, which is needed to rotate the left arm about its longitudinal axis, happen and when does the left arm rotary motion happen? Image 2 shows SMK gripping CC's left forearm when CC is at the P5.5 position and he states that the MOI is far too high at this time point for the M arm torque forces to get the left arm to motionally rotate counterclockwise (curved red arrow). Image 3 shows SMK gripping the club and he states that the left wrist must uncock (in the direction of the red arrow), which represents the release of PA#2, before the left arm can rotate counterclockwise about its longitudinal axis. Image 4 shows SMK pulling the club down to near-impact (~P6.8 position) and he states that one must get to this near-impact position (which markedly lowers the MOI) before the M arm torque forces can motionally rotate the left forearm counterclockwise and square the clubface by impact. That has been my "fixed" golf instructional position - you have to nearly complete the release of PA#2 before you can release PA#3. This CC/SMK presentation also shows that one cannot "tumble" (which is due to a left forearm supinatory motion) in the P5.5-P6.5 zone as many BM groupies believe - the club must first release in the plane of the intact LAFW (as shown in the video presentation and in images 3/4) until the release of PA#2 is nearly complete before one can "tumble" and rotate the left forearm counterclockwise about is longitudinal axis. SMK expresses the same opinion in graphical form in his research paper. Here is the graph from his paper. One can see that the M arm torque force is being applied at about the P5.5-P6 position. However, the MOI is too high at this point - note that Q arm (which represents the angular/rotary displacement of the left arm around its longitudinal axis = release of PA#3) only happens much later - in the late downswing between P6.5 and P7. All of that makes sense, and this represents my personal position as expressed in my review papers and my many posts in this forum. CC and SMK also briefly discuss the release of PA#2 in that video. CC gets down to the ground so that he can keep his clubshaft on one club-releasing plane as he demonstrates the club-releasing phenomenon (release of PA#2). Image 1 shows CC pulling his left hand towards the ball in a straight line directional manner (blue arrow). CC/SMK both agree that it would require a lot of active muscular forces (eg. the positive wrist torque force that is recommended by BM in phase 2 of the downswing) to uncock the left wrist (red curved arrow) under those conditions of a straight line hand arc path. Image 2 shows CC demonstrating a rounded hand arc path, and CC/SMK both agree that the release of PA#2 could occur passively under those conditions. In other words, there is no need for a large M wrist torque (positive wrist torque applied by the right palm against the back of the grip end of the club) if a golfer generates a rounded hand arc path - note how small the M wrist torque force is in SMK's graph and note that it is applied for a very short length of time. In other words, this has also been my position in my review papers - that the release of PA#2 occurs passively according to the law of physics and that it doesn't require a large positive wrist torque force (as recommended by BM in his "Ideas About the Release" video). Jeff.
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Post by chipitin on Oct 7, 2013 11:50:41 GMT -5
You do realize Manzella agree's with Sasho...right? It's stated in his post. If you asked him does he agree with Sasho the answer would be yes! So called "groupies" can misunderstand what is presented.
POSTER: Why is Hogan making that move? Is it his way to close his relatively open face or is it setting up another mechanical move key to his swing?
BRIAN MANZELLA:
1. His laying it off helps him square it up —ala Sasho's research.
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Post by imperfectgolfer on Oct 7, 2013 11:59:06 GMT -5
Chipitin,
BM may now agree with SMK's video presentation relating to the release of PA#3 (which is needed to square the clubface by impact), but BM never discussed this important PA#3 release issue (which happens in phase 3 of the downswing) in his "Ideas About the Release" video - and he only discussed the idea of "going normal" in phase 3 of the downswing (BM's statement related to "pulling up on the grip end of the club with all one's might"). Does BM now also agree that the release of PA#2 can be passive (and that it doesn't require a positive wrist torque to be applied by the right arm against PP#3) - as SMK/CC described the PA#2 release action in that video?
Jeff.
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Post by chipitin on Oct 7, 2013 12:03:07 GMT -5
He may have not discussed it at some point and then did later I don't know exactly when he did, I would have to check but I'm sure he was aware of it as Sasho presented his paper a while ago.
I would be pretty sure B.M. would agree with everything Saho said in that presentation.
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Post by imperfectgolfer on Oct 7, 2013 12:05:57 GMT -5
Chipitin,
Yous stated-: "I would be pretty sure B.M. would agree with everything Saho said in that presentation"
How can you be sure? Where is the "evidence" that BM states the release of PA#2 should occur passively according to the law of physics, and that it doesn't require a positive wrist torque in phase 2 of the downswing?
Jeff.
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Post by chipitin on Oct 7, 2013 12:09:50 GMT -5
You asked me and I told you as best I know, if you need actual verification then you would have to ask Brian himself. I would not be surprised if he said he agrees with everything Sasho presented in his demonstration on that subject.
I can say I do agree with it.
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Post by chipitin on Oct 7, 2013 12:28:08 GMT -5
What one "groupie" got from it.
drewyallop drewyallop is offline Senior Member drewyallop's Avatar
Join Date Mar 2009 Location Victoria British Columbia Canada Posts 929
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Maybe this will help clear up some confusion. This is what I got from the paper:
There are two planes defined. The "golfer swing plane" which is the plane traced out by a point in the middle of the lead arm wrist bone. The second plane is the "club plane" which is traced out by a line connecting the end of the grip and the centre of the clubface.
There are several simulations tested but they fall into three categories:
1. club plane above golfer swing plane at the start of the downswing
2. club plane below golfer swing plane at the start of the downswing
3. club plane the same as golfer swing plane at the start of the downswing
All else being equal number 1 makes squaring the clubface difficult, is the main cause of an over the top downswing, and a slice producer.
Number 2 makes squaring much easier. In fact the simulation with no forearm supination torque squared the clubface as long as the club plane was below the golfer swing plane at the start of the downswing. The illustration showing the moment arm explains why. There is a force in the direction of the arrow which pulls clubhead up closer to the golfer swing plane. This is I think is the tumble feel.
Number 3 assumes that the golfer and club planes are the same at start down and that gravity immediately pulls the club plane below the golfer swing plane (reminds me of Kevin's advice to let the hands drop). At this point two alternatives were tested.
In the first case the golfer immediately applies forearm supination torque. In the second case forearm supination torque is applied mid-swing i.e. when lead forearm is parallel to ground (the magic position).
Early supination was found to be sub-optimum. Applying supination torque at the start of the downswing results in something like premature ejaculation. The work stops before the job is done. Angular momentum increases very quickly at the start of the downswing but quickly peters out to nothing before mid-swing is reached (MikeG may want to provide a graphic showing the peter-out effect).
On the other hand starting the supination torque mid-downswing allows a smooth build-up of angular momentum to just before impact. Interesting to note that Kevin's advice to let the arms drop also implies that the arms are passive and relaxed at start down, thus no early application of torque.
Other things I think are significant ...
The best clubhead velocity was achieved by starting the downswing with the club swing plane and the golfer swing plane equal, the club plane then dropping below the golfer swing plane, then the application of forearm supination torque at lead arm parallel. For me this exact timing of the torque application is most difficult. The instinct is to start torquing right away. Patience! Let the arms drop.
The highest velocity downswing (sim5) showed the club swing plane 11 degrees flatter than the golfer swing plane at impact c.f. Mike Jacobs under the table video.
Clubhead velocities were significantly higher when forearm supination torque was applied compared to the passive case of letting the club square itself. Active rotation of the forearm resulting from a muscular torque can contribute significantly to clubhead speed.
Finally this quote from the paper ...
"The relationship that any variable (e.g. weight shift, delayed release, or swing plane) has on the outcome of a golf swing (e.g. clubhead speed, path, or face angle) can be understood by determining how that variable affected the force and/or torque being applied to the club by the golfer."
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Post by chipitin on Oct 7, 2013 14:14:18 GMT -5
Excerpt from paper:
For Sim3, the combined angular momentum of the forearm, hand, and club, relative to longitudinal axis of the forearm, was just below zero for the first half of the downswing due to gravity pulling the club below the swing plane (Figure 4c). The angular momentum then became positive for the second half of the downswing due to the forearm torque actively producing supination. For Sim4, the angular momentum profile showed the opposite pattern. The early supination torque resulted in positive angular momentum during the first half of the downswing. However, despite continued activation of the forearm supination torque generator, the angular momentum was negative between 0.17 and 0.23 s, and became only slightly positive during the final 0.05 s. Interestingly, the forearm torque was peaking (30 Nm, not shown) when the angular momentum was peaking in the opposite direction (-0.56 kg·m 2 /s) at 0.19 s (Figure 4c). The combined moment of inertia of the left forearm, hand, and club, relative to longitudinal axis of the forearm, was nearly identical for both simulations over the first 0.1 s of the downswing (Figure 4d). The moment of inertia then dropped quickly due to the ulnar deviation at the wrist bringing the center of mass of the club nearly in-line with the forearm. Ulnar deviation was delayed considerably for Sim3 in comparison to Sim4; hence, the associated delay in the timing of the decrease in moment of inertia for Sim3. The clubhead speed at impact for Sim3 (44.1 m/s) was 24% higher than that generated during Sim4 (35.5 m/s; Table II). The optimization algorithm found the muscle coordination pattern that resulted in the highest clubhead speed at impact while also ensuring the clubface was square to the target line. The clubhead speed for Sim3 (44.1 m/s) was 22% higher than that generated during Sim1 (36.2 m/s), which indicates as to how much active rotation of the forearm from a muscular torque can contribute to clubhead speed
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Post by chipitin on Oct 7, 2013 14:21:26 GMT -5
Below is a
perfect example of a "groupie" not understanding and listening to what Sasho is presenting. They clearly said that you can use a muscular torque along with the passive forces and they are not telling people to not use an active muscular torque to square the face (11:28 of the video) just that it's possible in theory for the face to square up without it.
I would love to know how to measure"ROC." Hitting blocks or not hitting blocks is a way to measure ROC? that might have something to do with other factors i.e. hand path etc.
How do you measure ROC between 2 players if both are hitting good shots?
JEFFY'S forum:
Robin Robin is offline
Join Date Apr 2012 Posts 70
interesting video though very hard to know what kind of RoC you can obtain with their passive torque theory vs trying to do it consciously i'm my mind the lower the better and more reliable but...
i'm not sure i really get it cause i kind of disagree with their vision i personnaly decreased my Roc by very large amount with conscious closing moves.
if i just flatten the shaft without supination and "let the passive torque" do the work for me = just UD, i would hit horrid blocks, or i'd have to roll it a ton, unconsciously...is this reliable i'm not sure
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Post by chipitin on Oct 7, 2013 21:47:08 GMT -5
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Post by gmbtempe on Oct 7, 2013 22:54:59 GMT -5
I watched this video this morning after marking it as watch later on my Youtube, maybe my bump got Jeff's attention.
I think it is very good, and provides a very clear explanation of the physics involved.
I had watch Brian's tumble videos and had always interpreted that move taking place much earlier in the downswing, something that never seemed to make sense to me on how you could actual do this in a golf swing.
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Post by imperfectgolfer on Oct 7, 2013 22:56:15 GMT -5
Chipitin, This is your quote from the SMK paper-: "T he optimization algorithm found the muscle coordination pattern that resulted in the highest clubhead speed at impact while also ensuring the clubface was square to the target line. The clubhead speed for Sim3 (44.1 m/s) was 22% higher than that generated during Sim1 (36.2 m/s), which indicates as to how much active rotation of the forearm from a muscular torque can contribute to clubhead speed." You are trying to claim that active muscular torque forces causing the active release of PA#3 increases clubhead speed at impact. However, you have not really understood the paper - because he states very clearly that the optimization algorithm had to achieve two goals simultaneously i) maximize clubhead speed and also ii) achieve a square clubface at impact. It is obvious that a golfer will have to slow down his clubhead speed (due to the sequential release of PA#4 => PA#2) if doesn't use any active release of PA#3 - presuming that he wants to have a square clubface at impact. If he actively releases PA#3 then he can swing faster - because he can then more likely achieve a square clubface at impact even if he releases PA#4 => PA#2 faster. In other words, SMK's computer modelling put constraints on a passive PA#3 release (Sim 1) by imposing a penalty - in the paper, SMK specifically stated that-: " Penalties were also incurred if the model was not in a proper position at impact, such as having the clubface misaligned with the target For example, the penalty for a misaligned clubface was calculated using an expression (penalty = [2x misaligment] that reduced the objective function by 4 m/s if the clubface was misaligned by 1 degree". In other words, Sim 1 was deliberately penalized relative to Sim 3 in SMK's theoretical experiment. Here again is SMK's graph. This SMK graph clearly shows that an optimum swing action requires a large amount of M arm torque to actively release PA#3 in the optimum manner so that the clubface becomes square by impact - but that minimal M wrist torque is needed to optimally release PA#2. It is obviously possible to use more M wrist force (positive wrist torque - as recommended by BM), but SMK has shown that it is not necessary/advantageous. You also quoted Drewyallop, a BM groupie, who is clueless! He wrote-: " At this point two alternatives were tested.
In the first case the golfer immediately applies forearm supination torque. In the second case forearm supination torque is applied mid-swing i.e. when lead forearm is parallel to ground (the magic position).
Early supination was found to be sub-optimum. Applying supination torque at the start of the downswing results in something like premature ejaculation. The work stops before the job is done. Angular momentum increases very quickly at the start of the downswing but quickly peters out to nothing before mid-swing is reached (MikeG may want to provide a graphic showing the peter-out effect)." That's pure BS! Applying left forearm supination torque at the start of the downswing cannot work because it throws the clubshaft over-the-plane (tumble action) and SMK showed that it is counterproductive to have the clubshaft move over-the-plane. It has nothing to do with Drew's idea that "angular momentum is petering-out by the mid-downswing". The only appropriate time to apply M arm torque to release PA#3 is to start at P5.5-P6 and then increase the degree of M arm torque progressively during the remainder of the late downswing. As SMK's graph shows M arm torque must be applied for a considerable time period before any Q arm angular rmotion becomes apparent (mainly between P6.5 and P7). Jeff.
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Post by imperfectgolfer on Oct 7, 2013 23:14:52 GMT -5
Chipitin quoted Robin, who stated the following-: "interesting video though very hard to know what kind of RoC you can obtain with their passive torque theory vs trying to do it consciously i'm my mind the lower the better and more reliable but...i'm not sure i really get it cause i kind of disagree with their vision i personally decreased my Roc by very large amount with conscious closing moves."
He is also clueless! SMK's video is about the release of PA#3 - which relates to the topic of achieving a square clubface by impact by rotating the left arm about its longitudinal axis in the pre-impact phase of the downswing. It has nothing to do with the topic of the ROC during impact which depends on whether one is a DHer or non-DHer.
Lifter and Eric Paul in the Jeffy forum are also clueless!
Lifter wrote-: "A strong grip also plays a vital role in encouraging "early shallowing" of the shaft Golfers with very weak grips tend to have internal rotation of the right shoulder early in the downswing and they square the clubface with a flip. In contrast, golfers with very strong grips have to fight to keep the face open and thus are adept at externally rotating the right shoulder and maintaining lag.."
How does a strong left hand grip predispose to clubshaft shallowing? Why should a weak left hand grip predispose to flipping? Why should a golfer with a strong left hand grip have to fight to keep the face open?
The great advantage of a very strong left hand grip is that one doesn't have to use any PA#3 release action and one can simply keep the back of the left wrist parallel to the inclined plane, and therefore the clubface square to the clubhead arc, all the way from P4 to P7.
EricPaul wrote-: "Personally, I think a strong grip and external rotation of the right shoulder go hand in hand instinctively. As golfers, we know instinctively that if we internally rotate, we're going to pull the snot of the shot. To get any chance of a square clubface, we have to externally rotate with a little side bend thrown in to help out. "
That's BS! A golfer will use right humeral external rotation between P4 and P6 with a weak or neutral or strong left hand grip - if he wants to keep the back of the GFLW/intact LAFW parallel to a shallow inclined plane for as long as possible between P4 and P6.
Jeff.
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Post by tomdavis76 on Oct 7, 2013 23:36:11 GMT -5
Chipitin quoted Robin, who stated the following-: " interesting video though very hard to know what kind of RoC you can obtain with their passive torque theory vs trying to do it consciously i'm my mind the lower the better and more reliable but...i'm not sure i really get it cause i kind of disagree with their vision i personally decreased my Roc by very large amount with conscious closing moves." He is also clueless! SMK's video is about the release of PA#3 - which relates to the topic of achieving a square clubface by impact by rotating the left arm about its longitudinal axis in the pre-impact phase of the downswing. It has nothing to do with the topic of the ROC during impact which depends on whether one is a DHer or non-DHer. Lifter and Eric Paul in the Jeffy forum are also clueless! Lifter wrote-: " A strong grip also plays a vital role in encouraging "early shallowing" of the shaft Golfers with very weak grips tend to have internal rotation of the right shoulder early in the downswing and they square the clubface with a flip. In contrast, golfers with very strong grips have to fight to keep the face open and thus are adept at externally rotating the right shoulder and maintaining lag.." How does a strong left hand grip predispose to clubshaft shallowing? Why should a weak left hand grip predispose to flipping? Why should a golfer with a strong left hand grip have to fight to keep the face open? These sound like questions from somebody who has never played golf! Again, this statement suggests zero knowledge of the difficulties actual golfers face when trying to swing the golf club.
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Post by imperfectgolfer on Oct 7, 2013 23:42:55 GMT -5
Jeffy wrote-: "These sound like questions from somebody who has never played golf!"
Typical Jeffy behavior - make an overt ad hominem insult, but avoid answering the questions by posting an explanatory counterargument that can possibly be analyzed and critiqued.
Jeffy also wrote-: "Again, this statement suggests zero knowledge of the difficulties actual golfers face when trying to swing the golf club.
He should add the following to the end of that sentence -: "--- especially if they get the wrong golf instructional advice".
Jeff.
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