Thursday, 21 November 2019

Solutions to Lengthen the Flat Spot. Part 5. Controlling Up and Down Movements: Little Help from Physics and Anatomy.


We asked the following questions in the previous article: what should we do to let the sweetspot guide our swings through the MOI axis automatically ? And how to make our forearms and wrists be parts of our clubs ? In order to find the answers we need to take into account a little of biophysics. Prof. Theodore P. Jorgensen, in his excellent book titled "The Physics od Golf", explains to golfers how to use angular acceleration and torques to their benefit on base of the experiments illustrated below (the stick symbolizes golfer's lead arm):




We can see that if the lead shoulder pulls the arm parallelly there will be no lead arm rotation; if arm is angled to the vector of pulling force, the rotation will happen.


The difference between Prof. Jorgensen's examples and our studies is since we would like to have both humera as parts of the body while both forearms be a part of the club. It should be pointed out that forearm rotation is much easier achievable than the rotation of the whole arm which is very important in view of a subtle difference between club's MOI axis and shaft. Such a scenario is possible only when arms are not extended or hyperextended. It is easy to see this making a simple excercise: extend fully your arm and rotate it -- the whole arm (humerus and forearm) rotates; when it is not extended (only a little not extended is enough) -- only the forearm rotates (we wrote about this phenomenon in the first series of our articles in 2010, see: 'The Arms'). Let us see now our diagramme based on the Prof. Jorgensen's examples below:



It is to be pointed out that the sense of rotation  will be always enhanced by the fact that the club rotated around its MOI axis and not around the shaft. Automation is full and the only one condition is not to allow the arms (especially the left one) extend fully at address and during the first part of the backswing. The lead arm will straighten unintentionally later on with the help of lack of centripetal force and, finally, with the help of gravity.
Nevertheless, there is one more important problem, namely the wrist joint that somehow links the forearm to the club. If  wrists are like the chain between two nunchaku sticks it would be perfect. Alas, it is not despite the fact that wrist joints are very mobile ones. The point is to allow its full mobility come into force.

The best solution for having both allowing the automation of forearm rotation as well as full mobility of the wrists I could ever find is a firm but loose grip. You might remember both articles referring to building automatically a very firm grip (i.e. 'The Tale of a Left-Handed Knight and a Lady with Fan' and 'Melting Two Hands into One. Rear Hand Joins the Puzzle' from the year 2014) -- they are very valid always. Tightening the grip by fingers' action has a very big negative effect on both cases. However, it is antisubconscious to let the grip be very loose as our subconscious mind does not want to let the club go out of our hands, therfore, we need to use a smart trick here. Please take a look on the following GIF (taken from one of my favourite Western movie titled "The Fastest Gun Alive"):




Put a special attention to how the Vinnie Harold character (played by a great actor Broderick Crawford) treat his guns before a forthcoming duel. He pronates both forearms to the inside using his thumbs in order to minimalize the friction between his guns and holsters and avoiding any potential blocking). Surprisingly, this action is in a great accordance with the process of forming the Bio-K grip (merging a strong lead and a weak rear hand position); it sort of tightens the grip several times before loosing the tightness. Watch closely again in a slow motion:




The above method works for us perfectly, but it can be one of quite a few ones. The most important goal is to ensure maximal loosenes of wrists while maintaining stability of gripping the club lightly.
If we are able to fulfill this goal everything become automatic -- forearms act involuntarily following the club rotating around its MOI axis and, in consequence, helping vividly in creating a repeatable shallow arc of the sweetspot that we want to achieve.

And here is a small video reassuming the whole subject:



Monday, 19 August 2019

Solutions to Lengthen the Flat Spot. Part 4. Controlling Up and Down Movements: Automatic Shallowing via Sweetspot.


Well, first of all I feel the need to apologize to my readers that they had to wait so long for this article. Although the general concept was in my mind already after finishing the previous part, I still required more time than I thought to find the most automatic method of shallowing the club in the downswing without jeopardizing the longest possible flat spot idea. The solution was so simple yet deeply hidden as I have never suspected the way golf clubs are being built can be of any help in biokinetics. If only, I always treated it as an obstacle remembering famous quote of Sir Winston Churchill: “Golf is a game whose aim is to hit a very small ball into an ever smaller hole, with weapons singularly ill-designed for the purpose”. He was very wrong, but ad rem.






The whole golf club moment of inertia axis is neither the same as the shaft axis nor it is parallel to the shaft axis. This happens because heads of all clubs (except some funky patters) sort of stick out of their shafts. Thus, the axis goes from the top of the club through the center of mass of the head which corresponds linearily to the clubface sweetspot (in fact, the axis would run a bit closer to the heel of the clubhead, therefore between the clubhead CoM and the shaft, but for the better understanding of the whole phenomenon let us leave it as it is).
Now, when a club is in movement while this axis is above the shaft (as in address while the head is sticking up and North assuming we face North) simple Newtonian physics make the head open or closed, depending on the orientation of the movement and the position of the clubhead in relation to the gravity vector. Simply saying, during the late backswing it will be opening and tending to go down behind us while during late downswing it will start closing and go to the ball.




What happens when the head is opening and going down ?  The CoM of the clubhead tends to go first outside than under the shaft because of gravity. In consequence, it additionally supports shallowing of the shaft axis. I said additionaly because the very gravity and the mass of the head shallows the shaft axis per se no matter if the head is being open or not, however the process of further opening of the clubhead thanks to the clubhead MoI makes it much more effective. Moreover, if the clubhead MoI determines the way the shaft should be shallowed it means, no more no less, that the clubface sweetspot controls the optimal way for shallowing the shaft -- no matter what is the natural method of shaft shallowing for a given golfer (see: previous article).

But how can we achieve this unintentionally ? The answer is easier yet more revolutionary than ever suspected. We need simply to let the clubhead CoM and the whole club MoI axis lead our forearms during their movements. Lead and rear arm behaves differently from each other because lead one is straight and rear one is bent during the swing motion. When the arm is straight the humerus part and the forearm part rotate together, when it is bent the forearm rotates independently on the humerus, moreover, the humerus range of motion is much limited in this situation. Forearms and wrists can easily spoil the result of the swing by their intentional motions and affect badly the technique of achieving the long flat spot, thus, we need to get rid of them.




We need to view the whole arm-club system as both forearms are part of the club, not the arm (i.e. a "device" that brings the club into motion) and let them rotate freely according to the motion of the club. It is to be pointed out that both forearms wil match their rotary movements to each other automatically as their common goal is to hit the ball with the face of the clubhead. Moreover, the CoM of the clubhead will automatically "steer" the sweetspot to the ball in a shallow way ensuring a long and stable flat spot area. Hence the idea of hitting the ball with humera (as the element linking arms and golf clubs are elbow joints) is so attractive -- there is no further need to take into account either a complex two-bone movements of forearms nor even more complex multibone movement of wrists. Last but not least, the "shorter" are distal parts of the body in our mind the easier is to match their movements to the main body movement. The great Ben Hogan would surely agree to the above taking into account what he said about the role of hands in the swing motion in his 5L book:
THE ACTION OF THE ARMS IS MOTIVATED BY THE MOVEMENTS OF THE BODY, AND THE HANDS CONSCIOUSLY DO NOTHING BUT MAINTAIN A FIRM GRIP ON THE CLUB. (p. 82 of the book)




What is also important, the famous Hogan's idea of two-handed basketball pass can be easily described as a humera motion with unintentional and subconscious motion of forearms that can happen because of the friction between hands and the grip combined with the weight of the golf club and its MoI (remember -- the whole club's MoI axis !). Please look at the below drawing from the 5L book and try to differ the shadowed parts (humera "belonging" to the body) from unshadowed parts (forearms "belonging" to the club -- or to the basketball in this case):





The fundamental questions now are: what should we do to let the sweetspot guide our swings through that axis automatically ? And how to make our forearms and wrists be parts of our clubs ? Are there true simplified solutions available ? I have been looking for real answers and hence I did not want to publish the above article earlier...