Previous planar models of the downswing in golf have suggested that upper limb segments (left shoulder girdle and left arm) move in a consistent fixed plane and that the clubhead also moves only in this plane. This study sought to examine these assumptions. Three-dimensional kinematic analysis of seven right-handed golfers of various abilities (handicap 0- 15) was used to define a plane (named the left-arm plane) containing the 7th cervical vertebra, left shoulder and left wrist. We found that the angles of this plane to the reference horizontal z axis and target line axis (parallel to the reference x axis) were not consistent. The angle to the horizontal z axis varied from a mean of 133 degrees (s = 1 degrees) at the start of the downswing to 102 degrees (s = 4 degrees) at impact, suggesting a "steepening" of the left-arm plane. The angle of the plane to the target line changed from - 9 degrees (s = 16 degrees) to 5 degrees (s = 15 degrees) during the same period, showing anticlockwise (from above) rotation, although there was large inter-individual variation. The distance of the clubhead from the left-arm plane was 0.019 m (s = 0.280 m) at the start at the downswing and 0.291 m (s = 0.077 m) at impact, showing that the clubhead did not lie in the same plane as the body segments. We conclude that the left arm and shoulder girdle do not move in a consistent plane throughout the downswing, and that the clubhead does not move in this plane. Previous models of the downswing in golf may therefore be incorrect, and more complex (but realistic) simulations should be performed.
You have described the Swinger's Standard Wrist Action (10-18-A) and its Sequenced Release (4-D-0)which requires the Left palm to be Swivelled On Plane during Start Up. It remains On Plane with the palm riding the wheel rim until the Release Swivel takes place, rotating the Shaft back on to its own Plane, ready to apply the selected Hinge Action (usually Dual Horizontal).
The Hitter has identical Left Hand to the Plane relationship as the Swinger at the Top, however it got there in a different manner. Instead of a abrubt Start Up Swivel, a Hitter turns his Left Wrist gradually just like an Angled Hinging motion. And so it comes back down into Release in the same way, a Simulataneous Release Motion.
hmmm, well at least it looks like i'm on the right track!
May I ask where in the book your reference is for this? The best of my knowledge is in 2-G, the 'true rotation of the hands' in impact with no relation or reference to 'turned' to 'vertical'. Moreover, Swivel is not mentioned in 4-C. 4-C are specific Wrist positions - versus 'Swivel' which is more general and not limited to specificity in that context.
This isnt necessarily for you....but....can anyone show me where 'start up' swivel is in the book? Just curious. Not that its not in it - I just dont remember it, nor can I find it (yes - I have my book now!).
This is where I got the references. But my statement does require a bit of 'dot-joining'.
4-D-0:
"Normally, only Swingers with their Standard Wrist Action (10-18-A) “Swivel” –- that is, actually rotate the Left Wrist –- through Release into its Vertical Position for Impact." [bold by tongzilla]
In conjunction with 10-18-A: Standard Wrist Action
"With this procedure with Wrist is Turned and Cocked (FCT) during the Backstroke which requires that it be Rolled and Uncocked during the Release. Only where this procedure is used, do the Hands “Swivel” into Hinge Action Position." [bold by tongzilla]
Also definitions in 4-C-1/2, which I can't be bothered to type at the moment . But briefly, Turned means "left palm faces directly toward that Plane.
As per above, it this needs to be done twice -- once going back, and once before Impact. Which is why I've called them Startup and Release Swivels. Even though the actual phrase "Startup Swivel" isn't in the book (but Release Swivel is).
Originally Posted by phillygolf
If the entire left forearm wedge is onplane (the entire left arm) - the left shoulder must be onplane...and on the backstroke, I feel it would need to be above plane (due to no axis tilt)....
Yes, I've made a blunder here -- more specifically, the Left Shoulder must be On Plane if the entire Left Arm Flying Wedge is On Plane also. But clearly the Left Shoulder is almost never On Plane at the Top. But how can one reconcile with the above?
PS: Someone who should be joining this discussion hasn't said anything yet
__________________
tongzilla
Last edited by tongzilla : 01-11-2006 at 08:54 AM.
Previous planar models of the downswing in golf have suggested that upper limb segments (left shoulder girdle and left arm) move in a consistent fixed plane and that the clubhead also moves only in this plane. This study sought to examine these assumptions. Three-dimensional kinematic analysis of seven right-handed golfers of various abilities (handicap 0- 15) was used to define a plane (named the left-arm plane) containing the 7th cervical vertebra, left shoulder and left wrist. We found that the angles of this plane to the reference horizontal z axis and target line axis (parallel to the reference x axis) were not consistent. The angle to the horizontal z axis varied from a mean of 133 degrees (s = 1 degrees) at the start of the downswing to 102 degrees (s = 4 degrees) at impact, suggesting a "steepening" of the left-arm plane. The angle of the plane to the target line changed from - 9 degrees (s = 16 degrees) to 5 degrees (s = 15 degrees) during the same period, showing anticlockwise (from above) rotation, although there was large inter-individual variation. The distance of the clubhead from the left-arm plane was 0.019 m (s = 0.280 m) at the start at the downswing and 0.291 m (s = 0.077 m) at impact, showing that the clubhead did not lie in the same plane as the body segments. We conclude that the left arm and shoulder girdle do not move in a consistent plane throughout the downswing, and that the clubhead does not move in this plane. Previous models of the downswing in golf may therefore be incorrect, and more complex (but realistic) simulations should be performed.
"Three-dimensional kinematic analysis of seven right-handed golfers of various abilities (handicap 0- 15) was used to define a plane (named the left-arm plane) containing the 7th cervical vertebra, left shoulder and left wrist."
Maybe those guys at Edinburgh would have got better results by using something other than C7 as the pivot centre ...but you're probably far ahead of me .
I'm a new contributor and an anatomy/physiology nut along with GSEM and PGA affiliation; I am compelled to clarify that wrists cannot rotate. They can only flex, extend, adduct, abduct, or circumduct from standard anatomical position. I have trouble understanding GM terminology. Only the whole arm or forearm can rotate. Forearm rotation is termed supination or pronation and whole arm rotation is termed either internal or external rotation or, in some circles, lateral or medial rotation. So is so called wrist rotation a form of forearm rotation or whole arm rotation. Mechanical advantage suggests that forearm rotation is great for opening jars and manipulating most faucets from hot to cold or on to off but not so great for manipulating a golf club. Whole arm rotation is much more massive, powerful, and precise than forearm rotation during a golf swing. Please explain or reply if my words provoke anyone.
Originally Posted by tongzilla
Great to see you posting again, Mike
Lets clarify and be more precise about what a Swivel is.
A Swivel is a rotation of the Left Wrist from a Turned position to a Vertical position or from a Vertical position to a Turned position. The former is what we usually call “Standard Wrist Action on Downstroke”, or more commonly known as a “Release Swivel”. The latter is known as “Standard Wrist Action on Backstroke” or “Start Up Swivel".
What does “Turned” mean? Per 4-C-2, “When TURNED…the left palm faces directly toward that Plane."
Putting both these concepts together, this means the left palm is “Swiveled On Plane”, per my previous post.
So what the Start Up Swivel does is to put the Left Arm Flying Wedge On Plane, so it can remain On Plane until Release, just before the Release Swivel takes the Left Arm Flying Wedge (or the left palm) Off Plane to get into position to apply the selected Hinge Action.
With a Flat Left Wrist, the palm of the Left Hand must be On Plane for the Club to remain On Plane.
Linear Mode
