|
Post by imperfectgolfer on Feb 11, 2012 10:28:59 GMT -5
I have added a new review paper to my golf website related to a critical review of Brian Manzella's release ideas. perfectgolfswingreview.net/ManzellaRelease.htmError-correction suggestions and positive/negative feedback will be appreciated. Jeff.
|
|
|
Post by imperfectgolfer on Feb 11, 2012 12:16:45 GMT -5
nmg wrote-: "Lets start at the top specifically figure 3. You state that the hub paths shown there are elliptical. Are they? They look elliptical at first glance but notice they are plotted on a rectangular grid. They should be plotted on a square grid. Nevertheless looking closer we can see that they are not elliptical. The "center" were it static which I doubt it is, is decidedly skewed towards the lower (second two phases) part of the curve."
nmg states that they should be plotted on a square grid, and not a rectangular grid. I agree. However, that is how Steve Nesbit plotted the hub path in his research paper and I have not altered it. Also, the term "elliptical" is the term Steven Nesbit used to describe the hub path at the BM AntiSummit II conference. I actually think that the "true" hand arc paths of the 4 study subjects are much more circular in appearance, and that "fact" is readily apparent if you look at the hand arc paths in Steve Nesbit's original paper - when he presented them without a background grid.
Jeff.
|
|
|
Post by imperfectgolfer on Feb 11, 2012 14:45:54 GMT -5
nmg wrote-: "They look like spiral segments." I have no idea why anybody would describe the hub path (hand arc path) as being spiral in shape. My idea of the term "spiral" is a circular path of constantly decreasing radius. I plotted the hub paths of two golfers in my review paper - David Toms and Robert Rock - and they look more close to being circular (or near-circular) than elliptical or spiral. I don't see anything like a spiraling-motion of their hand arc path near impact. Why should it spiral if they do not want to use parametric acceleration in their downswing action? Here are the hub paths of the four golfers in the Nesbit study. I don't see a spiral motion of their hand arc path near impact. Jeff.
|
|
|
Post by imperfectgolfer on Feb 11, 2012 15:34:08 GMT -5
I have modified the Nesbit hub path diagram in my review paper to make the grid squares more square in shape, rather than rectangular in shape - copying the idea of nmg's modified diagram (which I think is a more accurate way to present the diagram). Here is another diagram from the Nesbit paper. Note that the hub path radius of the 5-handicap male golfer doesn't decrease in radius in the last 0.04 seconds of the downswing, and note that the hub path radius of the 18-handicap female golfer actually increases in radius during that same time period. That's not reflective of a spiralling phenomenon! Jeff.
|
|
|
Post by imperfectgolfer on Feb 11, 2012 18:20:31 GMT -5
nmg wrote-: "Shown is the golden spiral (Fibonacci spiral) superimposed over the computer optimized hand path from one of Nesbit's studies. He took his scratch golfer's starting path and kinetic limitations and asked the computer to optimize (subject to the constraint of not exceeding his physical limitations). What is shown is what the computer found through millions of iterations with a golden spiral overlaid."
What parameters and instructions were given to the computer in terms of hub path "optimization" that would cause the computer to produce a golden spiral? What have these parameters got to do with the "real world" scenario of each individual golfer's body physique, anatomical constraints and biomechanical motions - that ultimately determine the 3-D motion of the hands in space during the downswing?
Jeff.
|
|
|
Post by imperfectgolfer on Feb 11, 2012 18:56:43 GMT -5
nmg,
You wrote-: "In summary.... the computer selected a golden spiral from a nearly infinite number of possible curves as being "Most efficient". What this says is the golfer should get his/her hands on that golden spiral."
Why is the golden spiral hand arc path "most efficient"? What do you mean by "efficiency" in this context"?
Jeff.
|
|
|
Post by imperfectgolfer on Feb 11, 2012 22:18:55 GMT -5
nmg, We will have to agree to disagree. I have ZERO sympathy for an abstract concept that is superimposed on the "real life" world of human biomechanics - especially if a logical explanation is lacking. I believe that human beings have different hand arc paths due to different body shapes, different levels of body flexibility, different swing styles and different golf biomechanics. Many professional golfers have a near-circular hand arc path that doesn't spiral in the late downswing, and that type of hand arc path is perfectly suitable for playing world-class golf. Robert Rock's hand arc path Efficiency (defined in terms of the "most bang for the buck" type of hand arc path required to generate maximum clubhead speed) is only part of the equation - because maximum clubhead speed is dependent on many other factors other than the shape of the hand arc path. Secondly, maximum clubhead speed is only one desirable goal when it comes to overall golf swing efficiency - clubhead control and clubface control are of equal importance and there is no "evidence" that a golden spiral type of hand arc path will optimize those elements. Jeff.
|
|
|
Post by gmbtempe on Feb 11, 2012 22:21:20 GMT -5
I have a hard time relying on 2d video to determine hand arcs.
|
|
|
Post by imperfectgolfer on Feb 11, 2012 22:30:52 GMT -5
Greg,
Who is relying on 2-D videos for hand arc paths? I think that 2-D representations of hand arc paths are only relatively accurate, but surely accurate enough to differentiate between a circular hand arc path and a hand arc path that is greatly affected by a major element of parametric acceleration (eg. Lexi thompson's hand arc path).
Jeff.
|
|
|
Post by imperfectgolfer on Feb 12, 2012 9:45:08 GMT -5
nmg,
You axiomatically believe in the golden spiral.
I do not believe in axioms when it comes to golf swing mechanics, and I base the golf instructional material, contained in my review papers, on general/inferential conclusions drawn from studying the "real life" swings of professional golfers.
Good luck with respect to your possible future endeavor of proving that the golden spiral hand arc path is a desirable/optimum goal for all golfers.
Jeff.
|
|
|
Post by imperfectgolfer on Feb 12, 2012 13:09:25 GMT -5
nmg wrote-: ""General/inferential conclusions" eh.... Honestly isn't that just a euphemism for "opinions" and aren't "opinions" just like noses... everyone has one?"
Exactly!
That's all I have ever manifested - opinions. Nothing is different today. The same situation applies to all golfers (including nmg).
If anybody doesn't agree with my opinions, they can freely harbor contrary opinions (like nmg).
nmg wrote-: "Here is a fundamental fact from technical drafting: three dimensional information cannot be extracted from a single isometric 2d projection. At the minimum multiple simultaneous views of the same subject are required. Consequently all those lines... all those dots which would be golf science empiricists such as yourself put on pictures and video are absolutely meaningless."
They may be meaningless to nmg, but they are not meaningless to any rational person who understands their limitations, and who understands that multiple views are required for a better representation.
Jeff.
|
|
|
Post by imperfectgolfer on Feb 12, 2012 13:41:35 GMT -5
nmg,
I think that your golden hand arc path "belief" that it is the optimum hand arc path for all golfers is purely a "belief" (faith-based opinion).
Jeff.
|
|
|
Post by walther on Feb 12, 2012 17:05:42 GMT -5
nmg, I think that your golden hand arc path "belief" that it is the optimum hand arc path for all golfers is purely a "belief" (faith-based opinion). Jeff. Jeff --- From a somewhat impartial third party view --- I believe your outright dismissal of a postulated optimal hand arc path is premature and borders on hubris. w
|
|
|
Post by imperfectgolfer on Feb 12, 2012 18:47:47 GMT -5
Walther,
I haven't dismissed it - I have only stated that it is a postulate (faith-based) with no scientific support. Even nmg stated that he may one day attempt to work on providing the scientific proof when he stated-: "In time god willing I will prove mathematically not only that the optimal hand path is a golden spiral but also the the human body is capable of producing that geometry and that it's the best in terms of biomechanics".
He still has to work on the mathematics and he still has to show that the i) human body is capable of that geometry and ii) that it has the optimum (best) applicability with respect to human biomechanics.
Talk about hubris!
Jeff.
|
|
|
Post by imperfectgolfer on Feb 12, 2012 19:46:16 GMT -5
nmg, You asked-: "Jeff... Are you kidding? There is more SCIENCE backing the Golden Spiral Golf Swing conjecture than anything you've ever presented! Again... I reference Nesbit/McGinnis. Are you suggesting their paper is not scientific? You think that paper represents "their opinion"? The only scientific part of their hub path paper was the study of 4 golfers - where they explored the hypothesis that there could be a causal association between the hub path radius and maximum clubhead velocity. They only had 4 subjects, and in two of those subjects, the hub path radius did not decrease during phase 3 of the swing. Therefore, their study could not show any conclusive relationship between a shortening of the hub radius and maximum clubhead speed at impact. In fact, Nesbit stated the following in their conclusion-: " The specific effects of hub path radius on club head velocity are difficult to isolate since club head velocity represents a summary of the effectiveness of the golfer in generating and transferring energy through the various kinetic quantities to the club which individually are related to the hub radius to different degrees as discussed." In the final section of their paper, they attempted to artificially optimise clubhead speed via a computer program (unspecified in its parameters) and they could get an extra 4% increase in clubhead speed. In his swing model, there is no dealing with the release of PA#3 (rotation of the left arm along its longitudinal axis), and Steven Nesbit openly admitted at the BM AntiSummit II conference that his model has that major deficiency. In his paper's conclusion, Nesbit stated-: "The shape of the hub path appears to result from a complex combination of achieving equilibrium between the golfer and the club, and a purposeful configuring of the path to control the outward movement of the club while minimizing the kinetic loading on the golfer yet transferring the maximum kinetic quantities to the club. Artificially controlling and optimizing the hub path of the better golfer in the group indicated that a non-circular hub path was superior to a constant radius path in minimizing the kinetic loading while generating the highest possible club head velocity." That's the total extent of his conclusion, which is appropriately tentative and very non-specific. He never talks about the "golden spiral", and he never makes any claims about its applicability to a golf swing. If you believe that it has applicability, then the onus is on you to work on the mathematics and simultaneously also show that the i) human body is capable of that geometry and ii) that the golden spiral has the optimum (best) applicability with respect to human biomechanics. Talk about hubris - lecturing me about the "scientific method". nmg also wrote-: "In hard sciences such as dynamics there is only one solution. In the hard sciences only one answer is the correct answer. This is how we keep planes in the air, cars on the road and buildings standing. No wishy washy "I believe" psuedo-science allowed." I agree that there is only one answer in the hard sciences. However, human biomechanics is not a "hard science" and therefore any scientific study relating to the field of human biomechanics has the major problem-issue of many confounding variables. It is therefore "wishy washy" to believe that one can easily achieve a high degree of scientific conclusiveness when performing a small study consisting of 4 subjects. Sample size is a critically important factor in determining the appropriate sample size for a scientific study of human subjects - see perfectgolfswingreview.net/stackstudy.htm Jeff.
|
|