balls or centered? Forceplates...?

[art]

just dug this thread up from way back, i was interested in these questions also.

does anyone know where to find any force plate data for PGA tour pros (or any good golfers) re: their weight shift (especially toes vs. heel)? i have been looking online but haven't found much more than a couple youtube videos and i'm not sure if those golfers are the ones to look at for an optimal move. i'm hoping for some basic video or still images (or a description) of a good golfer and how that weight moves heel to toe and left side to right side.

my specific question was whether more weight on the toes of my right foot (and less on the heel) at the top would make "goat humping" less likely.

Dear Brian,

The answer is 'at least centered between the ball and heel of each foot' to start, with a personal preference for a more rearward location because of the dominant dynamic disturbances coming with/from the explosive down swing.

This is a wonderfully productive area and I believe the gate-way to improvement for many golfers. The most important message is that this process starts as a STATIC weight distribution, but then , as soon as motion starts becomes a DYNAMIC problem with FORCE SHIFTS, not WEIGHT SHIFTS.

Weight shifts are ONLY the vertical components of what is happening DYNAMICALLY, and as I hope everyone on this site is aware, IMO, dynamic balance and stability margin is different for every body, for every club, and maybe for every swing.

As for the theme of where those of you that have some scientific interest in this area can find some interesting data, I would first recommend Dr Kevin Ball's Thesis of a few years ago where as I remember, he studied 62 golfers swinging 10 times each on force plates, and measured the movement of the body at 8 different times during the swing.

On the commercial side, Dan Goldstein has developed and sold the Dynamic Balance System (DBS) to 50-100 users including the PGA Teaching Facility in Florida, and his DBS website, and contact address may be able to provide some additional foot force traces..

I personally anxiously await some testing on double force plates that have the capability to measure and process ALL the forces, vertical, and the horizontal (shear) forces both down the target line, and towards and away from the ball. Some work don at the University of Southern California (USC), by Dr. Jill McNitt, used this equipment in studying as I remember it, the golf swing as it may affect golf shoe design.

I sure hope this curiosity continues regarding these FORCE SHIFTS as IMO, it will strengthen the desire for the a better understanding of why BBKIB works for the lower body, and what mus be done regarding the upper body, and the shoulder complexes, the other major rotating elements of the body involved in the complex golf swing.

Regards,
art (and for the record, I wish I was mandrin, or better yet, could meet him sometime SOON, please)

 

[drewyallop]

The Japanese pro Hidemichi Tanaka was studied on force plates and the results might surprise some people.

Weight Shift in a Professional Golf Swing | Steve Pratt's Hit It Longer.com

From the linked article ...
"Looking at stage 5, or impact, you can see he weighs 184% of his actual body mass ...this reflects the shift in his body centre of gravity"

Wrong, I think. It reflects instead the "jump up". A shifting of the weight without any upward acceleration of the body would simply show the actual body mass, in my view.

 

[Frans@France]

As for the theme of where those of you that have some scientific interest in this area can find some interesting data, I would first recommend Dr Kevin Ball's Thesis of a few years ago where as I remember, he studied 62 golfers swinging 10 times each on force plates, and measured the movement of the body at 8 different times during the swing.

link : http://vuir.vu.edu.au/1432/1/Ball.pdf

The main and most important conclusion of this study is two different styles exist in
the weight transfer profile in the golf swing. In this study, two major groups were
identified by cluster analysis; named as the Front Foot group and the Reverse group.
The Front Foot group began the swing from a balanced position, moved the weight
towards the back foot in backswing, rapidly forward in early downswing and
continued towards the front foot through ball contact. The Reverse group was similar
to the Front Foot group in backswing and early downswing swing events. However
from early downswing the forward movement of weight stopped and began to move
towards the back foot through ball contact. Both groups included professional or elite
amateur golfers and no difference existed in Club Velocity at ball contact or Handicap
indicating neither technique was a technical error.

 

[dbl]

Great Link, thanks Frans

 

[art]

link : http://vuir.vu.edu.au/1432/1/Ball.pdf

Dear Frans@France,

Thanks for posting the link and summary of Dr. Kevin Ball's thesis. With his then adviser, believe it or not Dr. Best, (for Best Ball), they published several more papers based on the raw data acquired for Dr. Kevin's thesis.

At that time I contacted them hoping to have access to the raw force plate AND launch monitor data they used for all the tests on the 62 subjects. Unfortunately, several attempts failed, probably because of the distance between Australia and California, but if there are readers of this blog, near Victoria, Australia that hopefully may even know these fine folks, please read on.

In 2007-2008, disappointed I could not review the data as noted above, I was led to DBS, and then Dr.Michael Thompson and his 'Weight Right' force plate, efforts. Using these systems, it became obvious very quickly that the 'target line' (transverse) weight/force shifts were interesting BUT the lateral (anterior/posterior) force shifts towards and back from the ball were the dominant characteristics governing the golfers dynamic balance, and therefore IMO, were the primary dynamic forces, and reflex reactions were that determined the quality of the shot.

So ANY data that Dr. Ball may have recorded in this anterior/posterior direction would be of GREAT interest to me, and I hope many other folks, as the force plates used did have the capability to record the horizontal/lateral shear forces too. In fact, some of these forces were used in the 'moment' calculations in the lateral directions, to 'refine' the accuracy of the position of the center of pressure (COP)/ Center of gravity (COG) calculations.

So in summary, the anterior/posterior ground reaction forces are VERY important in understanding the dynamics of the explosive down swing, and will certainly help answer the question as to where the foot force reactions should be felt, BALLS OR CENTERED AND INSIDE OR OUTSIDE EACH FOOT.

Regards,
art

 

[Jim Kobylinski]

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