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Kinetic link
I am interested in your opinion as to which of these two graphs represent the "correct" body sequencing in a body swinger.
Graph 1  Graph 2  The first graph is the result of research by the TPI researchers and they claim that the arms/shoulders/pelvis rotate at roughly the same angular speed in the early downswing (before the end of the early downswing = lead arm parallel to the ground) in an excellent golfer. By contrast, the second graph implies that the hips rotate well before the shoulders and that the shoulders only start to rotate when the pelvis has reached about 50% of its maximum angular velocity. This graph also claims that the shoulders have roughly equal speed to the pelvis when the pelvis reaches its maximum angular speed. A third implication of the second graph is that the degree of torso-pelvis separation increases in the early downswing - because the pelvis is rotating while the shoulders are not rotating. This is in contrast to the TPI researchers result. Here is another graph from the TPI researchers - who have used high resolution (6-degrees of freedom) motion sensors (at 200 frames/second) to resolve exactly what happens in the early downswing.  This graph shows that the shoulders are actually moving at a faster rotational speed than the pelvis in the early downswing, which means that the degree of torso-pelvic separation must be progressively decreasing in the early downswing. So - which graph depicts "true" reality for an excellent body swinger? Jeff. |
Now isn't this funny, on iseek here you are prononcing yourself an exbert and here your showing you clearly don't know what your talking about asking for advice.
Isn't it funny another company backs and produce the same graph as we do, but then T.P.I argue different, but then again T.P.I six dof system is inacurate. If two companies are producing the same chain wouldn't that indicate maybe T.P.I are wrong, if two research companies who have been in the game for years provide graph maybe T.P.I are wrong. Your misinterpreting the graphs, they aren't saying the shoulders aren't moving all it's saying is the hip start first,then shoulders follow. but this what happen unless your trained in how to correctly understand and read the graphs you develop the wrong perception of what they mean like you do, in order to understand these graphs, you need to have studied biomechanics and been trained |
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I'm not a biomechanic,but I can read a graph.
All I see is that all the components are moving all the time in the -hips shoulders- arms- club- sequence. Or am I missing something?:golf: |
Biomechanic
I am not asking for advice. I have my own evidence-supported opinions on which graph is likely to be more accurate. I am merely asking for alternative opinions. If someone, like you, has an opinion that the TPI graph is inaccurate and that it doesn't represent reality in a body swinger, then that person is free to provide an explanation as to why the TPI graph is inaccurate. I personally have substantial reasons to believe that the TPI graph more closely represents "true" reality. Jeff. |
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The second graph is Kinetic Link..umm where did you get that graph from and how old is that graph? |
now isn't this interesting, your not trained , you have no qualifications in biomechanics is this going to be a ,Jeff say so,
that T.P.I are right, They can't determine hitting and swinging with their graphs cause they haven't the technology or knowledge to do it. There using a cheap $40,000 6 dof machine and can't measure in space, they also measure from vertical position. What golfer stands vertical ? Do you want a list of golfers of swings they have destroyed and cause injuries to. Funny , you can tell your not educated in the world of biomechanics. You would know their data is in accurate. |
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drewitgolf,
Was an older version of kinetic linking not that it has change, this came from the god father of biomechanics, A biomedic engineer who help create the software for force data, motion data and EMG data, which T.P.I are using EMG data software , according to the creator , that their software is very debatable to how accurate their software is. To be put nicely, more was said : ) This guy founded golf biomechanics and put it the map. But Sir Jeff still wants to debate this. Unqualified VS God Father? |
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Biomechanic - seeing that you are new to this forum, perhaps you should notify the forum members here that you work for a company that is competing with TPI. That will allow them to evaluate your comments with special care.
There are two approaches to this issue. The first issue is what represents the correct measurement data and the second issue relates to the issue of biomechanical plausibility. I will first deal with the issue of the correct measurement of angular velocity. The TPI researchers describe their methodology in this pdf paper and they contrast it with the technology used by Zenolink. http://perfectgolfswingreview.net/KinLinkvsKinSeq.pdf If one reads the paper, one can see that the TPI researchers use a totally different methodology of measuring angular velocity in the sense that they do not relate it to the PTS plane, which is apparently a requirement of Welch's zenolink technique. It would be interesting to see both measurement techniques used on the same golfer to see whether the graphs produced by the two different systems are radically different. I find the Zenolink's results problematic for a number of reasons. Here is a link to a golf instructor who is using the Zenolink system, and you can see the type of graph produced by Zenolink. http://www.biosporttechnologies.com/html/biomechanics_golf_swing_kinetic_link.htm?action=bi omechanics_gskineticlink That graph is near-identical to the graph that was published in David Leadbetter's book on the "Fundamentals of Hogan" (which I posted). One can see that the pelvis rotates faster than the shoulders in the early downswing and that the shoulders eventually rotate about twice as fast as the hips, and the arms eventually rotate twice as fast as the shoulders. This result is very different to the TPI researchers' findings. Why should there be a doubling of the maximum rotational speed as one proceeds from pelvis => shoulders => arms? I cannot think of a plausible biomechanical reason for this reputed-to-occur phenomenon. Can you? Note that the text states-: "Once the hips segment reaches maximum speed, deceleration begins to occur. This “braking” action transfers speed to the shoulders segment, which accelerates to a maximum value usually twice that of the hips." The statement implies that the "braking" action of the hips transfers energy and therefore increases the speed of the rotating shoulders. Can anyone provide a rational biomechanical explanation for this amazing assertion that pelvic deceleration in the early-mid downswing will cause the upper torso to rotate faster? Here is another link to a Zenolink-connected website. http://www.briankinggolf.com/zenolink.html Note that it has the following series of statements-: "A normal effective pattern would be one in which the hips segment accelerates first. The hips segment would accelerate to a peak speed at which time it would be rapidly decelerated from within the system. The shoulders segment would accelerate through the point of hips segment peak speed. Through conservation of momentum and the summation of speed the shoulders segment would reach a higher peak speed than that of the hips segment at which time it too would be decelerated." What do you understand by this claim - "through conservation of momentum and the summation of speed the shoulder segment would reach a higher peak speed"? That statement would seem to imply that COAM is involved in energy transfer between the rotating pelvis and rotating shoulders. However, I cannot understand how COAM can be involved in a system that is actively producing more energy. The concept of COAM only applies to a system where the amount of energy inputted into the system is fixed and the entire system either slows down or speeds up dependent on the distance of the mass of the revolving object from its central axis. Here is a nice U-tube demonstration of COAM. http://www.youtube.com/watch?v=ebjHSJM2bec Note that the experimenter spins the rotating object until it acquires a certain speed and the system is then left to spin at a certain speed. If the friction at the end points is small, then the rotational speed of the rotating structure will remain constant for a finite period of time. However, during that finite period of time, the rotational speed of the rotating object can be slowed if its shape changes so that it becomes wider (like an Olympic ice skater moving the arms away from her rotating core axis). The key issue is that the system has a "fixed" amount of energy and its rotational speed depends on its physical shape (like an iceskater who is spinning on the ice). COAM has nothing to do with the transfer of energy from one body part to another body part in the early-mid downswing. COAM may affect the speed of movement of the central arm in a double pendulum swing model during the release phase of the peripheral arm, because when the peripheral arm releases the radius of the double pendulum structure (central and peripheral arms) increases, and this must slow the speed of rotation of the central arm - presuming that no more energy is inputted into the double pendulum system after it is torqued by the central torque generator at the start of the pendular swing action. In that sense, one can understand how COAM may cause the arms to slow in the late downswing when the club passively releases (after all the power accumulators have released their energy). COAM cannot be operant in a hitter's action because the hitter is actively driving the clubshaft all the way into impact. The major point that I am making is that the principle of COAM surely cannot be relevant in the early-mid downswing when torso muscles are actively contracting thereby causing active rotation of the pelvis and shoulders, and I have no idea what the author means by the statement "through conservation of momentum and summation of speed". The second issue relates to the rough accuracy of the TPI researchers' measurement of angular velocity and their general assertion that the shoulders rotate slightly faster than the hips in the early downswing. I think that there is substantial evidence that this is true. Here are three confirmatory evidentiary sources. Source 1. Here is a table from a research study that measured the angular velocity of the pelvis and shoulders at different time points throughout the downswing. http://perfectgolfswingreview.net/MyersTable.jpg One can readily see that the shoulders turn faster than the hips at the very start of the downswing and turn much faster than the pelvis at the end of the early downswing (lead arm parallel position) - and these results confirm the findings of the TPI researchers. Source 2 Here is a series of capture images from a birds-eye view swing video of a very good golfer and I measured his torso-pelvis separation angle throughout the early downswing.  Note that the torso-pelvic separation angle decreases from 48 degrees (at the end-backswing) to 37 degrees (at the end of the early downswing) and that is due to the fact that the shoulders are rotating faster than the pelvis throughout the early downswing - as predicted by the TPI graph and the other research study. Source 3 Here is another graph from an independent laboratory (Jim McLean' laboratory in Florida run by Rob Neal)  Note that this graph is much more similar to the TPI graph than the kinetic link graph - in the sense that the shoulders start rotating fast from the start of the downswing and travel at roughly the same speed as the pelvis (slightly slower in this measured sequence) while the kinetic link graph predicts that the shoulders don't turn at all in the early downswing. Jeff. |
Quote By Jeff "However, I cannot understand how COAM can be involved in a system that is actively producing more energy. The concept of COAM only applies to a system where the amount of energy inputted into the system is fixed and the entire system either slows down or speeds up dependent on the distance of the mass of the revolving object from its central axis."
Just a clarification- For anyone studying movement and getting the wrong impression of the above quote. 1) When you consider the concept of Conservation of Angular Momentum as the total angular momentum always staying the same in a closed system and therefore, if you move mass further from the center of rotation then there is a slowing of the rotational speed- then you might agree with Jeff's quote and say " That doesn't exist in a system where you ARE adding energy. 2) When you consider the aspect of Conservation of Angular Momentum - that in ANY rotating system - when you move mass further from the center of rotation- that has a slowing effect on the rotational speed- you'll see that the principle stands true whether you are in a closed system or system where you are adding energy. The only issue is - how much mass has moved, how much slowing is that creating and when, where and how is the added energy affecting the overall result. When you keep that perspective in mind - then Jeff's quote can be very mis-leading, confusing, etc. In summary, your thoughts on this thread Jeff are definitely worthwhile areas to explore - I just thought I would attempt to clarify this one area that stood out for me. The principle of conservation of angular momentum exists in every rotating system. |
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If you are really interested ..go and get yourself tested by both of them and compare what each are offering |
Mike - I generally agree with your position that COAM could theoretically be acting on a rotating system while energy is still being inputted into the system - like that rotating structure in the U-tube demo. However, it would be very difficult to quantify the effect of COAM on the speed of rotation of the entire system while the person is actively spinning the rotating system. Secondly, the principle of COAM applies to the entire rotating unit (how its overall speed of rotation is affected by the distance its mass moves away from its central axis of rotation) and it has nothing to do with the transfer of energy from one moving body part to another body part. In the kinetic link theory expounded on the Xenolink website, there is an evidence-unsupported belief that energy is transferred from the pelvis => shoulders => arms via "a conservation of momentum" principle that involves a braking phenomenon whereby the slowing of rotation of one body part causes another body part to speed up. . Can you understand the physics/biomechanics that could underlie such a "belief". I can understand the kinetic link working in a snapping whip, whereby the sudden braking action of the rope handle of the whip transfers energy down the length of the whip to its peripheral end thereby causing the peripheral end to speed up. However, the whip is a totally inert physical structure that doesn't generate power within itself - it simply responds to the hand movement of the person wielding the whip. During a golf downswing, a golfer is actively contracting a multiplicity of muscles that cause the pelvis and shoulders to independently turn at a certain rotational speed. There is certainly an interaction between the rotating pelvis and the rotating upper torso - in the sense that the movement of the lower torso transmits physical forces to the upper torso via the spine and truncal musculature/ligaments. However, the golfer is also actively rotating the upper torso during the downswing and it would require some very sophisticated experimental testing (using muscle probes in a variety of truncal muscles) to determine how much of the upper torso's rotational speed is due to active torso muscle contracting versus passive physical forces transmitted from the rotating lower torso. I have never heard of any researcher performing that type of experimental testing. Have you?
Regarding your concept of the TGM pivot-stroke swing - do you think that the pelvis/shoulders/arms are rotating at roughly the same speed in the early downswing - before the lead arm reaches the parallel-to-the-ground position; or do you believe in the kinetic link theory where there is a time-sequential transfer of energy that causes the pelvis to move first, the shoulders second, and the arms third with each sequentially moving part maximally rotating at exactly twice the speed of the preceding moving part? Jeff. |
Pistol
I think that the critical issue is not Welch's proprietary software program that measures the angular velocity of different body parts during the downswing. I think that the critical issue is the underlying physics/biomechanical principles that underlie Welch's thinking when he eventually interprets his measured results. That's what bothers me! It is his underlying ideas regarding "conservation of momentum and summation of speed" due to a braking phenomena that bother me, and his consequent idea that each rotating body part must get sequentially accelerated to exactly twice the speed of its preceding rotating body part via this braking phenomenon. Jeff. |
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Regarding your concept of the TGM pivot-stroke swing - do you think that the pelvis/shoulders/arms are rotating at roughly the same speed in the early downswing - before the lead arm reaches the parallel-to-the-ground position; or do you believe in the kinetic link theory where there is a time-sequential transfer of energy that causes the pelvis to move first, the shoulders second, and the arms third with each sequentially moving part maximally rotating at exactly twice the speed of the preceding moving part?
Jeff.[/quote] The problem i see here is it depends on the definition of when a backswing has finished and a downstroke has started ..Kinetic Link may have a different view on this opposed to TPI..and which player is tested. For instance ..the hips can have a running start on the shoulders due to the pressure being moved to the reAR foot and the center of mass being in front of the pressure being shifted to the rear foot and this can occur in the backswing..so the shoulders have some catching up and then of course so do the arms due to how Far they have to travel |
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Jeff,
Who do you work for? What is your background? I am not trying to be rude, I just would like to know your qualifications and how you come to your conclusions. |
Pistol - you wrote-: "The problem i see here is it depends on the definition of when a backswing has finished and a downstroke has started ..Kinetic Link may have a different view on this opposed to TPI..and which player is tested."
Your belief about different definitions of the end-backswing may be true, and that's why I believe in standardised definitions. Cheetham, of TPI, has recently accepted what I regard as the only scientifically-supportable definition for the end of the backswing - when the club changes direction. All the latest TPI graphs now use that strict definition for the top/end of the backswing - rather than vague criteria eg. when the shoulders stop turning or when the pelvis reverses direction and starts to move forward (a phenomenon which actually may occur during the backswing in many good golfers). Jeff. |
Rhythm - I think that your questions are partly meaningless, and I don't know what's your real agenda.
When you ask "how do I come to my conclusions" it is like asking a person how he thinks with respect to "cause-and-effect" relationships. I have a certain way of personally solving the issue of "cause-and-effect" relationships by using a multiplicity of scientific principles eg. Humean logic relating to contiguous events in the absence of confounding variables, Popperian experimental testing procedures that rigorously test a theory for its falsifiability quotient, Haackian criteria relating to concordance between different theories in a particular field of science (web of belief ideology). Jeff. |
COAM does not apply
No....
COAM only applies to systems that are subject to a "CENTRAL" force. A central force is one which is directed through the axis of rotation. In the youtube Jeff attached, the spinning device is compressed and stretched by force with is acting THROUGH the axis of rotation. That is a central force. Its would be impossible to argue that the forces generated by a golfer's muscles during the golf swing gestalt act in a direction which is through the "instantanous" center or axis of rotation. Therefore usage of the term COAM when discussing golf is wrong. COAM does not apply to the golfswing contrary to what some authors and their experts would have us believe. no_mind Quote:
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Lab Rats
Bagger / Bambam,
This is a worthwhile discussion, but it is not housed appropriately in the forum TGM Advanced. Please hasten all posts and participants to an identically-titled forum in The Lab. Thanks. :salut: |
Rythm,
Jeff has no qualifications, he claims himself to be interpreter, he pulls stuff off the net and adds his twist, the reason he doesn't understand what chris does is he hasn't no understand or education in biomechanics. Now Every one I left T.P.I cause their data was wrong and I destroyed golf swings in the process, there data doesn't measure up to be right. the human body doesn't function the way they are claiming. They can't measure hitting and swinging, the kinematic graph doesn't replicate what a student is truly doing in their swing,, not at all no comparision. SO I LEFT , THEY ARE THE WORST BIOMECHANICS RESEARCHERS GOING. There K-vest is a joke the data is so far out it's beyond a joke. when you have students over the top the vest is lighting up green you can't measure the so called T.P.I kinematic sequence. all you can measure is hips and shoulders. I have first on experience and worked for K-vest T.P.I , I have full understanding inside out of the technology used and was highly trained. From a hands on experience and screening students the results told the story, the metrics were terrible. I had to change my metrics on my vest to the original metrics K-vest first use, it was that bad. T.P.I can't comment on what we do they have not the technology to measure be able to compare. And this is why jeff can't understand how we do it. And we aren't going to put it out for the public either, so people can steal the technology MikeO is right you can measure coam if you have the technology to do so. T.P.I can't cause they have not the technology, they have a cheap 6 dof system which can't measure antomical time (in space) they are surmating their metrics , guessing another words. using maths They also measure from vertical position, not as a player stands in golf swing position, this leads to data being further out. Our difference is we can measure anatomical time we don't use sumating T.P.I can't measure anatomical time (in space) and they do sumating. (guessing) of coarse you will get different out comes they are guessing we aren't. If you ever want to get further from the truth in how a swing works in biomechanics follow T.P.I |
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Jeff,
T.P.I are selling K-vests now if they were smart wouldn't they realize you can't put 6 degrees of freedom data into 3 degrees of freedom technology. So their information is not applicable anyway so whats the point. why do you think they can't apply a hand sensor it's six dof data not three dof to be able to do this? Also you have to be able to measure in space( anatomical time). T.P.I can't measure in space. now this is comical , I have to laugh here. So if they ever release the hand sensor for k-vest or arm sensor it will be guessing or summating. So it's useless to us. We don't want guessing we want accurate data. Jeff do you know what summating is, I know you never use to use this word until I started talking about it and educating people on what the word means. so I'm interested if you know what it really means or you just picked up this word by scanning my threads in other forums. We still retain 6 dof application in our screenings for starters , how can you compare a 3 dof system to six dof are you serious. were are talking about applications for the consumer here, T.P.I use 3dof k-vest, we use 6dof data you can't compare the two nor will the kinetic chains be the same. I think it is funny for application use T.P.I are trying to fit 6dof data into 3 dof data , this will happen when monkeys talk and pigs fly. Makes you question the intelligence of T.P.I. This can not be done unless you fudge the metrics like they did the first time round. |
no mind golfer
I don't mean to be rude are you jeff's twin brother, the way you write and express yourself is very similar characteristics as Jeff's and to come forward like you did back Jeff on your very first post seems very odd to me. :naughty:
who are you and what is your back ground, I'm interested |
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Jeff,
You must really enjoy hearing yourself talk...huh?:sleepy: Answer the question... What are your qualifications? I have no agenda. I just want to know the best way to measure the kinematic sequence... I am a TPI certified instructor, but I am always learning. |
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Better yet- let's use a non-golf example and you can explain what you mean: If you are pushing someone on a merry go round- are saying that it wouldn't matter how close there were to the center- it would take the same amount of force to move them the same RPM's? That wouldn't be the case- so maybe in that example you would still consider the force - "instantanous center of axis of rotation". Or let's use an ice skater- the ice skater uses muscles to extend the arms out - and there is a slowing of the rotational speed. So it's not that muscles are involved that ceases COAM. Help me see your point. |
Jeff,
are you for real , you are quoting brian kings words on the kinetic link , not what zenolink describe the kinetic link as, are you serious who are you trying to kid. This Brian descriptions not the researchers and founders of zenolink. You pick a quote off someone's web page trying to sell lessons thats not research:naughty: surfs up good to see your surfing at your age, on your net surfing sorry. You quote the same graphs on every website all over the world. The link on comparisions is off tpi's websites of coarse it will be one sided they are trying to sell k-vests . What research is this who can you provide this as evidence or research, this is pulling peoples opinions off the net , not actual research.:naughty: The final graph you present did you see the golf swing , do you ever bother to think this person could have also had an over the top swing as well. :naughty: Did you ever to bother to think the graphs T.P.I present are swinging over the top, does greg rose even know what over the top swing is ? he is a chiropractor. the last graph you present is ball velocity not on the biomechanics of the swing they are measuring ball velocity, once again did you see these people swings were they also over the top swings. There is a difference between net surfing and research Jeff, how about doing real research before you start presenting to the world who is right and wrong in biomechanics. I can't laughing stop:laughing9 this is a joke what are you trying to prove. Is T.P.I paying you? |
Pistol, I'm not sure I understand the question. Let me say this:
At every point in the golf swing the equations of motion apply ( F=ma and M = I alpha) These are of course three dimensional. Im mass in the parts of the system gets redistributed then that changes the moment of interia (I) in the second equation. F (force) comes from gravity (small contribution minor really) and muscle contraction. When those force act on levers they cause Moments (M) which create rotation. Muscles and gravity do not create central forces so as it is strictly defined in all physics/mechanics texts, COAM does not apply to the golf swing. Quote:
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Nmgolfer whats your opinion of TPI kinmematic Sequence and K-Vest? |
on resumes and logical fallacy
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It would be meaningless for me to tell you my background because background (resume) is not proof of a claim. Besides it really does not matter where or how one comes by their knowledge, only that it be factual. Although I am not an autodidactic (with respect to this subject), I hold nothing against those who are. If I were to claim my statements are true on the basis of my background it would be an example of: ARGUMENTUM AD VERECUNDIAM or the "Appeals to authority" logical fallacy. Appeals to authority are always deductively fallacious; even a legitimate authority speaking on his area of expertise can get it wrong. The testimony of any authority is no guarantee that anything is true. no_mind |
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Still don't get where your're going with this. A diagram might help. Quote:
Frankly its not exactly clear to me what exactly it is they are trying to sell... that is...what problem it is they are trying to solve. If its not just technology for technology sake one thing is clear... they are leaving their potential customers with mistaken impressions with regards to what is and is not happening durning the swing. I assume you are familiar with the term "snap your chain"? |
Let me elaborate... at any given instance Gravity is actin on the mass of the golfer and some combination of the golfers muscles are contracting. If we were to take a snapshot in time and add up all of those forces vectorially it would have a manitude and direction. That force must be reacted or our body will accelerate (move) and its reacted by shear and normal forces at our feet. The shear and normal forces at our feet are "equal" but "opposite" (direction) to our muscle forces and gravity. That direction is not directed (necesarily) through the axis or center of rotation so its not a "central" force.
At issue is verbage. Conservation by definition implies: "limited supply" . When are muscles and gravity are applying forces which create momments we are increaing (or decrease) alpha or angular acceleration and conservation does not apply. Only if those forces are directed through the axis of rotation and therefore cannot create a torque are they central forces. I'm saying COAM does not apply. I'm not saying as mass gets redistributed the system won't speed up or slow down... The only way to know whats happening is by solving the equations of motion at each instant in time. |
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your very knowlegeable and I hope you except my apology, And what if you can measure motion at instant in time. this can be done you can measure each segment speeding up and decelerating. if your only applying coam from the spine to the hands then can coam be applied? |
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In summary, of course strictly speaking conservation of angular momentum does not exist in the golf swing as it is not a closed system and we are adding energy to it. However, that doesn't mean that changes in distribution of mass doesn't affect the rotational speed as described in the conservation of angular momentum formula. |
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I'm a bit amused by all of it. If you've read that other forum (before the Manz deleted all of my posts that is) then you already know my answer. Lots of buzz words but from my vantage... very little substance and virtually nothing that's going to help your average golfer.
Frankly its not exactly clear to me what exactly it is they are trying to sell... that is...what problem it is they are trying to solve. If its not just technology for technology sake one thing is clear... they are leaving their potential customers with mistaken impressions with regards to what is and is not happening durning the swing. I assume you are familiar with the term "snap your chain"?[/quote] He deletes posts and contradicts himself all the time nmgolfer so its a hard read.."snap your chain" could mean anything so I don't know what he is getting at ..maybe breaking the chain on the old toilet flush mechanism.. |
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