Thursday, 15 April 2010

The Early Elbow Plane



The EEP (early elbow plane) is a logical result of benefitting from one of the golden rules of (bio)physics concerning the perpendicularily of the distal parts motion to the spine (core).





The EEP is a description of a biophysical phenomenon when a classic double shifter achieves the EP relatively very early in the downswing with the shaft bissecting the forearm; a decent amount of lag is necessary to perform the EEP. An EEP golfer receives full support from both rear humerus (in relation to the body alongside with which is moving) as well as from rear forearm that supports the shaft and clubhead until impact being in-line with it and at a perpendicular angle to the core.

The best example is post-accident Hogan who achieves the EEP very early in the downswing (his rear elbow moving forward early and fast after transition) until shaft becomes in-line with rear forearm and rear forearm perpendicular to his core. From this moment there is his turning main body only, the rest is in status quo in relation to it which may be certainly considered as the best possible biomotoric scenario for consistency in the downswing phase:




As we already know, the backswing must be lead by the rear side, for the reasons mentioned earlier. It won't let a too inside takeaway which is the main enemy of flattening the shaft plane after transition = one of the biggest enemies of the downswing EEP. The best results are achieved if it is being performed sequentially from the ground up at ca. 45* angle up & back. The downswing phase occurs sequentially from the ground up as well thanks to an automated transition that is possible thanks to finding limitations in the joints sequentially from the ground up. The overtorques in the joints cause the trampoline effect when changing the orientation of the motion (from backswing to downswing). The lower the body part the sooner it finishes backswing and the sooner it starts downswing. It creates optimal condition for the plane to drop (congruently) from TSP to EP as soon as possible.



The Diagonal Stance


I am of the opinion that the feet should be in the diagonal stance position always when the pelvis area motion happens, no matter what is the length of the club. Practically, only putter stance would require a square stance, since we do not need any hip joint motion. In order to achieve it the rear foot ball should be in line with the lead foot heel, therefore, sort of diagonally to the target line. Of course, this position is offsetted via different feet position - the lead one is flared while the rear one is square to the target line.
This diagonal stance has one more very important merit, in my opinion. When the downswing progresses, the rotational aspect relocates gradually the CoG to the lead foot heel. At impact, the CoG line should optimally run from the knee joint to the ankle perpendicularily to the ground (letting the knee joint maintain some flex necessary to allow the joint to rotate and guarantees the best possible stability). It is not already at the heel but definitely is closer to the heel than to the toes. The opposite scenario happens with the rear foot where the heel loses its contact with the ground first, maintaining the contact in the area near ball/toe. Now, when we create an imaginary line between those contact points of both feet it can be parallel to the target line only when feet are placed in a diagonal stance position. This creates a necessary torque, since the hips are already open at impact, does not allowing to transfer the CoG too early to the lead heel (causing the lead knee to straighten too early). The same torque does not allow the weight to be left on the rear side too long as well.
Of course, the smaller hip area motion is required, the less diagonal stance is necessary.

Last but not least, the diagonal stance gives a much better base for a human body weight. The bigger surface the base has the easier is to be in balance through the motion and, what is even more important, the easier is to use the ground shear forces comparing to when all body parts are in line with each other. Human feet are very small in relation to the entire body mass that they must keep in balance, especially during such a dynamic motion as the golf swing is.
 
Here is the diagramme of the Diagonal Stance. The blue line is the target line, the red squares are the address pressure points of both feet and the red lines are linking the pressure points setting the feet (see also the blog part dedicated to feet pressure points where everything is explained in detail):




The above diagramme is, in fact, a corrected version of the original Hogan's stance diagramme published in "5 Lessons":




Watching thousands of Hogan's clips (as well as some other great ballstrikers - Sam Snead, George Knudson and Mac O'Grady come to my mind first) I consider the DS concept as much closer to reality than the latter diagramme. As Mr.Hogan's friend and playing partner, Gardner Dickinson said "[...] he experimented with putting some wrinkles in his left wrist. Ben gradually changed his grip so that his left hand showed about one and a half knuckles at address. At the same time, he let the right hand move more on top of the shaft so that the "V" formed by his thumb and forefinger pointed between his chin and left ear. He then moved the ball forward in his stance, and repositioned his hands at address so that they were about even with the ball, or even slightly behind it with a driver. Finally he assumed a distinctly closed stance at address, even on pitch shots, by withdrawing his right foot from the intended line of flight. Ben aimed with his shoulders, not his feet, so the closed stance had minimal effect on his targeting."

Jackie Burke likes to call the concept "runner's stance" underlining the dynamism of a static position. If you imagine how would a runner stand ready to start the race next words are not necessary at all.


Mr.Hogan's (and other great ballstrikers') stance allowed to locate the downswing vertical axis of rotation in the same place towards the lead ankle joint; the rear foot moves back the longer the club is, makes it finding the bottom of the arc earlier.
A flared lead foot allows to find the limit of rotation of the lead knee faster than the rear one. The knee that cannot rotate further bends inwards what almost automatically makes the weight shift on a lead hip joint when the linear CoG shift happens. If the lead foot is put inward, instead flared, all tension in the knee and hip is lost. Moreover, the sum of small X-factors is being achieved properly when the lead hip "stays" early in the backswing allowing the rear shoulder find its limit without making the backswing too long and loose. Lastly, during the downswing it guarantees a proper correlation of the pelvis position and the impact position. Hips are open at impact, thus, the lead foot should not be square to the target in any case if the aim is to ease the rotation.


Watch Mr.Hogan sets his feet in search for a ground forces and totally balanced motion with the lead foot always flared out and the rear one perpendicular to the target:




Observe how Mr.Hogan seeks for a stable stance that would guarantee the most effective usage of the ground forces. A closed toe line, open hips and square shoulders (in relation to each other), a flared lead while a squared rear foot plus different pressure points for both feet - these are the real keys.

Closed feet, open hips, squarish shoulders = the essence of the diagonal stance. Other words - shoulders are closed in relation to hips but open in relation to feet. Hips are (strongly) open in relation to feet and (less) open in relation to shoulders. Feet are (strongly) closed in relation to hips and (less) closed in relation to shoulders.
Imagine one wants to start a sidewise dynamic physical activity directed at West (assuming one faces North at stance) - can be hammering a nail at the West wall or starting to run to the West, or whatever - the diagonal stance will be chosen best by ones subconscious mind as the most effective one. Hogan knew it and, by an occasion, it appeared to be the best possible stance type to apply D-plane consequences with the fixed ball position (which is a very huge convenience for a golfer if one does not need to think about 14 different ball positions).
Simply ingenious statically and dynamically.




The intention is setting joints the way it is useful both for backswing as well as for downswing. That's why Hogan's diagonal stance is pure genial thing, who knows, maybe the most important thing ever. The rear foot is being settled the way it helps to automate the transition while the lead one to support the vertical axis of downswing rotation the best possible way, i.e. having the mass vector going down through the ankle joint or ensure continuous rotation during the impact zone.
Besides, both feet position match the relationship between hip joints and feet separately in both planes, sagittal and coronal during the setup - on the level of subconscious mind. Rear foot matching backswing while lead matching downswing. It is heavily linked to the process of independent setting of both feet at angles:


The Sagittal Plane Compression Concept. Part 6.



It is very important to underline that the crucial thing when seeing the motion through compression and expansion elements is to understand that the expansion elements are framed within compression ones. I mean there is no expansion that does not begin and end with a compression. That's why the working name of the concept is the Sagittal Plane Compression and not the Sagittal Plane Expansion.
This concept reflects a perfect example of creating and using the kinetic energy in the swing motion. The compression allows to store energy and pass it to the passive side of the body sequentially from the ground up which can happen only when the orientation of the motion corresponds with the active side of the moving body.

Compression is being controlled by the natural limitations of the human body based on stable skeleton/joints structure. Muscles that are generators of the energy cannot be used to control - they must be controlled by something stable. The joints won't let the muscles waste the energy while they find their natural limitations during the torquing process. Moreover, they will allow to react into the opposite direction using the same energy since the limitation is one-sided only - as e.g. during the transition providded there is a weight shift to the rear side with preset rear leg joints (bouncing wall effect).

Expansion, as a process always enframed between two compression phases, is in fact being controlled by those compression phases of the lower located parts of the body (vide: transverse planes). I know how silly it sounds but actually this is what happens. It won't sound silly if we take into account that the compression/expansion phases occur sequentially in time from the ground up. For instance - the transition - when the legs have finished their transition compression and are already in the expansion phase, the pelvis actually is in the middle of its transition compression and the upper body is still in the backswing expansion phase. The chain of events works by itself almost automatically then. Say, the expansion phase of the body part that is located higher meets the compression phase of the lower located one which won't let another scenario to happen unintentionally.

What is also of big importance -- pulling vs. pushing issue. Each compression phase requires taking the momentum over by the other sagittal part of the body fluently. It can be done only via pulling from the core out. However, the smaller is the gap to the next compression phase (or by the end of the expansion phase) the more pushing instead pulling occurs -- as pulling converts into pushing with the momentum already rocked on. The leading side starts to push it as pulling would guarantee no further acceleration.


Observe how Mr.Hogan builds the frim rear side sequentially from the ground up thanks to the rear ankle and knee joints preset. Observe how his rear hip reacts unintentionally to the sequentially built torques and moves linearily. Observe how Mr.Hogan can ensure automatically that the downswing is a pure undisturbed rotation as a natural consequence of what has just happened before in the motion or even during the setup.

Mr.Hogan's whole swing is a beautiful compilation of compression and expansion phases that occur in a proper sequence from the ground up thanks to properly built torques in the joints.
As we know it is called a Sagittal Plane Compression (SPC) concept:






How the firm rear side can be achieved automatically in practice ? Observe closely Mr.Hogan's rear feet action at setup in this video:




The action contains a clockwise turn of the rear ankle and knee joints without changing the rear foot square to the target line position till the limit. Turning the rear heel outwards first (this makes the foot perpendicular to the target) and then turning out both joints. Like one wants to bring your rear heel inwards again, which won't happen because of shear forces between the foot and the ground.
One should imagine that when standing on ice your rear foot would spin outwards because shear forces are practically not present. Since there are a lot of shear forces between one's foot (armed with spikes) and relatively soft ground, a substantial amount of torque is being built. One will feel the torque. One will also see that your rear knee joint bends slightly inwards as a consequence of this action.
It is one of the most importants little secrets of Mr.Hogan aimed at building the firm rear side from the ground up that, consequently, leads to automation of the whole motion.


Here is the photo of the BGST author presenting rear ankle/knee joints (BTW, as well as the rear elbow joint) presets:


The arrows show the torque vectors while the blue slanted line shows the natural reaction of the knee joint to the process of its presetting. The bending inward is an additional help when building the firm rear side from the ground up.

The Sagittal Plane Compression Concept. Part 5.


The main goal of the SPC concept is not only to automate the golf swing motion but also to ensure that the kinetic chain of events is being built and released properly. While understanding how the energy is being created is relatively easy a task, the most confusing aspect is the releasing of the stored energy up to the clubhead - mainly because there is no change in orientatiuon of the motion.
Actually, it is a very simple phenomenon that allows to release the whole kinetic chain in a proper way and is a very important part of the SPC concept called the second (impact) compression.
In order to understand it well we must differ the two scenarios - a. compression phase that is aimed at the change of orientation (direction of movement) and b. compression phase that happens without the change of orientation (direction of movement). The first one of course happens between backswing and downswing, while the second one happens at impact when the whole kinetic chain is being released at the ball. The chain is the whole human body starting from the ground/feet ending on the arms/hands/clubhead. The release is just passing the stored energy to the more distal parts of the system and it is done via consequent stalling of former links in this chain - i.e. in order to pass the energy to the arms, the main body and the shoulder joint must stall.
But during downswing nothing can stall because the body is in constant rapid movement till the finish. So how to pass the energy to the arms ? Look at this photo sequence:





The ball position indicates vertically when the chain is being released correctly. It means that the lead shoulder should (hypothetically) stall at this line in order to let the distal limb and, consequently, the clubshaft and clubhead to release the energy and achieve the peak velocity. If the lead shoulder continues to move linearily to the target in a 2-D, the chain wouldn't be released at all.
However, if the lead shoulder, which must be still in rapid motion, stops to move horizontally and starts to move vertically up (say, on the red line up) in 3-D, so the chain must be released because its position in relation to the ball does not change in the horizontal 2-D sense - say, the ball "sees" the lead shoulder stalls completely.

So, as we can see, it is really a very simple physical phenomenon that allows the compression phase to occur without stopping the motion and without changing the orientation of the whole movement. Moreover, it guarantees automatically that the angular velocity of the clubhead (as the most distal part of the system) increases as per parametric acceleration phenomenon. The second (impact) compression phase:







Another crucial element of the SPC concept worth special mentioning is the Trigger Compression.
The backswing is biokinetically sound when its being lead by the rear side of the body in the sagittal plane - it is biomechanically most efficient if the side that leads should have the same orientation of motion.  After addressing the club, the best ballstrikers triggered the swing with the rear side push targetwise that simply provide initial inertia and guide to pull the entire rear side back and up at 45* angle while maintaining spine angle till natural limits sequentially from the ground up. The initial trigger compression also clears the way for subconscious mind, so to speak. It rocks all the motion and put it into work smoothly and correctly.
Otherwise -- how one could start the motion without conscious mind engagement ?

Moreover, every motion benefits physically from a move aimed at rocking on the motion. This is what the trigger compression does for a golf swing. And it is not just forward press done by arms - it is the whole rear side compresses at the firm lead side from the ground up - just as those great ballstrikers performed:








After the trigger compression, the rear side uses the created momentum (say, as bouncing from a rubber wall) and the whole rear side takes the momentum and starts naturally to pull up, around and back creating torques in the joints from the ground up. Using the TC phase practically will leave no option for a golfer but utilizing the initially built momentum via the active rear side in the backswing. The rest is just a chain of unintentional events that everyone should dream of.



The Sagittal Plane Compression Concept. Part 4.



Even the best mechanics + conscious action is not comparable to good mechanics + untentional action, especially happening as a sequence of events where one element follows another because there is no other way. Let me take as an example pelvis area motion. There are three basic possible scenarios for pelvis movement in a rotary golf swing performed by a bipedal (not mentioning scenarios of hip sliding back and forth):
a) the rear hip goes consciously as far back as possible in the takeaway to ensure enough deep position of the rear hip to exclude the necessity of lateral shift later on in the swing (see: Clement's "Hogan" drill);
b) the lateral shift happens at the end of the backswing as one of consecutive unconscious events ensuring that the downswing is a pure rotation (see: Hogan);
c) the lateral shift happens in the downswing phase as a conscious action starting it (see: Stack&Tilt pattern).
In view what was written before, the serious advantage of the scenario b) is undoubtful.

According to my researches (not only mine, BTW - such authorities as e.g. VJ Trolio even wrote a book especially about it), Hogan's pelvis area action is one of his "secrets". His pelvis moves linearily targetwise before he completed backswing of his upper body. IMO, the trick is to be able to do it early enough so that the downswing can be a pure rotation.
Pre-secret Hogan did not perform his linear shift early enough which resulted in a necessity of mixing linear and rotational components in the motion which is easily visible on some vids. Many other differences between and after "the secret" might have been caused or at least influenced by it.

Hogan wanted to have his linear shift to happen as early as possible so that the downswing is a pure rotation while the weight is located correctly under the lead ankle. The linear shift symbolizes for a bipedal that there is no possibility of coming from the outside - while he had it 100% guaranteed what he wanted ? A rotation. An OTT move. So that he cannot hook the damned ball. He wanted a pure rotation that puts his clubhead more OTT onto the ball without any slightest possibility of slicing and power leaking - because he was so in-to-out just a second before rotation element and after linear element.
He was an unique genius.


Please watch the visualization of the SPC concept in the pelvis area:




And now a pure pleasure to see Mr.Hogan in action. Observe carefully Mr.Hogan's rear hip action. It moves linearily targetwise before he completed backswing of his upper body. It is not a conscious move - there is no time for it. It is either not a result of the deep rear hip takeaway - the hip move starts long after takeaway. It is a reaction of his pelvis to the torques that have been built thanks to creating the firm rear side sequentially from the ground up. The torques in the ankle and knee joints that cause the rear femur guide the rear hip joint the only one way - the way Mr.Hogan wanted. Observe how the ankle and knee joints release the tension (torques) just the moment the hips go linearily.
As said before, the linear part in the pelvis area must happen since humans are bipedals. The trick is to be able to do it early enough so that the downswing is a pure rotation which was one of Mr.Hogan most crucial secrets how to automate the motion and make it powerful enough independently of one's body build and individual strength.





The Sagittal Plane Compression Concept. Part 3.


Here is the general visualization of the SPC concept:


 
 
And here is the SPC concept video which is, in fact, an introduction vid to the Sagittal Plane Compression concept (SPC) that explains the optimal biomotorics of a human swinging a golf club in a macroscale. The motion that is totally free of conscious thoughts and uses the hard structure of the human body to build the sequence of events. The automatic golf swing is a dream, true, but the SPC concept can put the golfer much closer to this dream...:

   




The Sagittal Plane Compression Concept. Part 2.



Let's now introduce the SPC concept with reference to the pelvis. I personally believe it is the most crucial area of a human body when comes both to creating power as well as maintaining balance of the motion.

The pelvis is a multibone solid structure that links the upper body with the lower body. It is so important because our lower body consists of two limbs, therefore, the pelvis contains two very large joints called hip joints. The problems created by the pelvis motion, especially in rotary types of motion, are countless. The same is with the golf swing motion. Improper motion of the pelvis area can be the most often appearing culprit for inconsistency and lack of repeatability.


First, very shortly, it is worth to remind how both hip joints should work in a rotary swing (described in detail in the Main Body section). Hips are not just rotating. Both joints work as an eccentric wheel which means that their motion is a combination of rotational and linear movements. It has to be like that if we want to obey the golden rules of biomechanics concerning the motion of the main body equipped with two arms. Simply, the hips must be substantially open at impact in relation to the target line; substantially enough to let the main body be also open at impact.

Generally, the lead hip downswing motion contains mainly the rotational element while the motion of the rear hip contains mainly the linear one. This simplified idea matches ideally the SPC concept since the pelvis cannot be "compressed" any other way. Imagine now that the rear hip tries to take the impact position of the lead hip that, at transition, is North-West of it. Since the vertical axis of rotation goes through the lead hip - we are bipedals and that is why the most efficient rotation happens if the vertical axis of rotation is being transferred to one of the two hip joints. Having said that, I would like anyhow to stress that the CoG transfer is a more complex thing than just transferring 100% of the weight/pressure to the lead hip. It should be done neither too early not too late. This is one of the most important timing issues in the motion that can be, I do hope, excellently eliminated via the SPC concept.

OK, as it has been already discussed when talking about the spine, the rear side adduction that happens as a natural consequence of a correctly performed backswing is also the crucial force in the pelvis area. Before the lead side leads the parade via its abduction the sagittal plane of the pelvis should be compressed. It won't be if we start the transition by lead hip pulling as it was drawn in '5 Lessons' (famous elastic tape image), we need to let the rear hip adduct. If I were Mr.Ravielli, I'd draw a second, much thinner elastic tape that comes throughout the body to the rear hip to make all golfers be conscious about the rear side of the body working.



It all can happen only when the rear hip motion is being restricted only via finding natural limitation (thanks e.g. to rear knee joint preset). As we already know the lumbar part of the spine (as well as cervical one) will tend to set the direction of the movement to South-West and the rear hip moves linearily to the West trying to "compress" the pelvis in search of creating theoretical one common joint of the two, through which the vertical axis of rotation will run. It feels like we still let the lead side be pulled right when the rear side has already finished its abduction and starts to reverse the motion, i.e. starts to adduct. Moreover, it is a trampolline effect that accelerates the lead hip rotation. Lastly, the SPC will take care of a fluent and proper CoG transfer to the lead hip joint - without it timing issues can kill the swing. With it - we will have a decent degree of automatism in the motion of this area and we can let a powerful transition and downswing happen by itself. Of course, it all cannot happen without a correct legs/feets work and correct presetted stance.

Coming to the SPC of the uder-pelvis section we have to be very aware how the concept works in the hips area described earlier, especially what is the motion and function of the rear hip joint. Its linear movement should determine our stance as well as the motion of the rear knee joint.
The crucial thing is to understand that the rear hip joint is turning at the backswing phase with the smallest possible displacement in the coronal plane, i.e. on the North-South axis. The coronal plane is this one that dissect the body for rear and front halves. It is the lead hip joint that is moving on the circle in this phase as well as later during the downswing. There should be no change between those two phases since it would only create an unnecessary disorder in the fluency of the motion that must run in 180* opposite directions.
It matches perfectly the scenario of the SPC of both upper as well as pelvis area of the human body. The rear knee joint should be more South than the lead one at the top, so that it could move sort of behind the lead knee joint at transition. Of course, it is an almost invisible motion that compresses the plane between legs that, similarily to other areas of the body, is caused because of finding a natural limitation in its motion. It looks like, during a very short period of time, the distance between both joints decreases in a saggital plane while it remains the same in the coronal plane. Just imagine scissors.


Feet now - personally, I can see no particular reason why the stance should not help to perform the above described action. Moreover, I can finally understand the diagonal stance Mr.Hogan performed while hitting longer clubs and I am surprised he did not use it with his short clubs as well. Or better said, he did not described it in the book but the concept of the diagonal stance was often visible when he even hit wedges. Some Hogan theorists even claimed that his feet stance was always closed to the target line - only his lead foot was in a flared position that gave the illusion of a slightly open stance. In fact, Hogan's hips were in an open position in relation to his feet at his stance.

Please look for details in the posts dedicated to the Diagonal Stance.

The Sagittal Plane Compression Concept. Part 1.



This concept, that I call now Sagittal Plane Compression (in fact, the first working title was Sagittal Axis Twist but I disliked this because it was misleading a bit), refers to a lot of dynamic aspects that were not automated well in the whole Big Picture...such as CoG transfer at transition, proper pelvis area work, maintaining the CoG properly during downswing until impact and even influencing a proper knee bend angle. In short, it can be a true missing link in the theory.



First, what is the sagittal plane:



Shortly, it is a virtual imaginary plane that divides the whole body into left and right portions. The wide neurologic aspect that we are omitting now concerns human brain halves and their interactions. What we want to concentrate is only the physical actions of lead and rear body parts in the swing. There are two main notions that are associated with the sagittal plane - abduction and adduction.
Abduction is a movement which drives a part of the body away from the sagittal plane of the body and, therefore, it is opposed to adduction that is a movement which brings a given part of the body closer to the sagittal plane.

Long story short, I have concluded that the backswing phase can be mainly described as the abduction of the rear side (of course, it is simultaneously the adducton of the lead side) while the downswing is mainly the abduction of the lead side (of course, it is simultaneously the adducton of the rear side). I have categorized it this way since this is a real importance of motion in a golf swing while having the target on the lead side. It also matches pretty well the theory of Small X-Factors as well as the pulling force of the rear side during backswing as the most natural and efficient one (presented in details in The Main Body section). So - abduction of the rear side leads backswing - it contains not only main body pulling action but also rear arm and elbow joint pulling/folding action. Let's forget for the moment about lead side work, such as lead forearm rotation that happens in a completely different plane.

The downswing, OTOH, is mainly the abduction of the lead side - the main body pulling action and the lead hip action. Let's forget here about the magic of the rear forearm as a support to the above.

The crucial part in the whole SPC concept is dynamic interaction between those two abductions. As we know, the most consistent ballstrikers always started the downswing before the backswing ended, if I may simplify the phenomenon. It means in reality that the sagital plane must be "compressed" or "twisted" during the transition, creating a sort of a trampolline for the lead side of the body abduction.

Going further, it implicates that the rear side of the body must start its adduction before the lead side starts to act. It is not difficult a task at all because we can create necessary limitations in certain areas, such as in rear leg, rear eye or grip, etc. (all of them are described in those five sections of the thread). The SPC start to happen when the lead side inertia is being stopped by the rear side due to those limitations, but what is more crucial is that this effect is somehow doubled while the rear side starts to adduct.

The whole problem is to find a chain in the whole action looking at both sides of the body INDEPENDENTLY, and to find areas where the SPC might work (we need to remember that the base of the body, i.e. bones are hardly compressible). It would be necessary to "cheat" the skeleton.

I'd like to throw a trial explanation of the spine rotation influences and helps in automating the transition. The evolution shaped human spine in curves. The major part of the spine (thoracic part) is flexed while the two distal smaller parts (cervical and lumbar-sacral) are extended. Ironically, the thoracic part, that is braced with ribs for the most part is the part that rotates much more than the other ones. Why ? During the backswing, the cervical part rotation is being limited by the head movement that is limited by the eye sight range; the lumbar-sacral part rotation is limited by the very pelvis as well as by rear leg preset action at the setup.

The bigger amount of rotation of the middle part causes both distal parts to react accordingly when the small X-factors are being achieved. They both extend more than in a stationary mode in relation to the mid part; in fact, we can also state that the thoracic part flexes a bit more as well while turning back in relation to the other two sections.



This causes both the cervical as well as lumbar part of the spine go up and back (precisely in this order since the rotation of the shoulder area, i.e. upper part of the thoracic section is the biggest); when the backswing is complated correctly, a slight but noticeable shift towards South-West of the top of the spine can be observed; same happens a fraction later with the lumbar part that golf instructors often call informally as tailbone. South-West direction is exactly the direction of the perfect transition move that leads to a correct hip movement at the downswing in the rotary swing.

As a side note - the lower is the plane the easier is to find the limitation of the main body during backswing - high two plane golfers seldom find the maximum amount of the small X-factor of the shoulder girdle just because of the arms working on a higher plane.

The Biokinetical Grip. Part 2.

As promised, the series of photos showing all important aspects necessary to understand how to build correctly the Bio-K Grip. Please watch carefully the photos as well as read the comments.

When a man stands freely, the natural orientation of the direction of palms and elbows are as follows:



The direction of both elbow sockets is in line with the direction of palms. The clavicle bones are in a perfect neutral position. It remains the same when we bend as in the address over the ball:




When we move both hands in order to blend them together they are still at a 90* angle towards each other, therefore, one of two hands is on top of the other being simultaneously perpendicular to it; on the pic, the RH is on top because it is like this in reality on a grip:




The 90* angle between both hands ensures the maximal possible effectiveness of the wrist movement in the swing - the lead wrist cocks/uncocks (radial/ulnar deviation) while the rear wrist hinges/unhinges (dorsi/palmar flexion), and the orientations of those motions are exactly perpendicular to each other:




In order to achieve it, the lead hand grip should be as strong as possible (with the so-called short thumb for control)...:




...while the rear one should be as weak as possible...:




...without and lack of comfort. Some people can achieve a bigger angle between both Vs, some a smaller one. What is worth remembering is the bigger (or better said the closer to 90*) the angle between both Vs is the closer we are to the maximally efficient grip. However, there are some anatomical limits (different for different people) that are great checking points. First, there should not be any gap between the ring finger and the grip. Such a gap can be created when the RH grip is too weak. Secondly, the RH pinky finger should be able to hook around the LH index finger and the strength of this hook must be big enough to ensure a proper tieing of both hands.


The Vardon overlapping grip is the best for two reasons: 1) it lets all the fingers (except RH pinky only) lie and exert pressure on the grip; 2) RH pinky finger can easily wrap around the mid joint of the LH index finger, because, as all fingers, it has three parts and two joints. It should look either Mr.Hogan presented in '5 Lessons' or, in an exaggerated to the maximum version, like this:



Please note that such a method of hooking the pinky finger is much more stable than a conventional method of putting the RH pinky finger in the slot between mid and index fingers of the lead hand. The more, with a strongish position of the LH the LH index finger becomes in sort of a trigger finger position and the mid joint is being raised, creating a great base for the pinky's wrapping around action.



Finally, the weak RH position on the grip forces automatically the RH index finger to be in a trigger position, that is really important in sensing the lag as the most important pressure point on the grip.Moreover, the weak RH position creates the optimal condition for presetting the rear forearm turn at address (that has a lot of importance in both the upswing as well as the downswing). The preset should be visualized more or less like the combination of the weak RH and keeping the elbow socket up from the beginning till entering the impact zone (what Mr.Hogan recommended to Mr.Venturi):



Please take into account that the above mentioned photos are an exaggeration presented so that the whole concept is clearer.

Lastly, the desirable takeaway effect of the Bio-K Grip, namely, the rear elbow socket up during the takeaway - first, the BGST author statically...:



...and then the Golf Master dynamically:





The Biokinetical Grip. Part 1.



I have paid attention to the relation of natural position of the wrists and the position and function of clavicles. Long story short - it is important for stability and ergonomy of the motion of the upper part of the main body (torso) to keep the clavicle bones in neutral position as long as possible, or, at least, to start the motion with it. What is important, clavicles not only transmit physical impacts caused by the arms motion but also ensures a maximum possible range of motions for arms - provided they are in a neutal position. It is a very important thing, IMHO, for bringing automatism in putting strokes - I'll get to it later on.


Going back for a natural position of the wrists, we shall find that neither "anatomical position" (palms are directed forward) nor "gorilla position" (palms are directed backwards) is natural for the wrists. When we stand freely and let our arms hang freely too, we can observe that the plane of the palms (both of them) are angled inward at ca. 45 degrees. And this is how the hands should be placed on the grip in order to maintain the neutral position of clavicle bones. As I said in my posts dedicated to the grip in this thread - both palms are angled to each other 90 degrees letting to align naturally the lead wrist cocking (radial deviation) with the rear wrist hinging (dorsi flexion).



For the moment, I find the "biokinetical grip" as extremely superior to the classic grip for the following very important reasons:

- creating optimal conditions for the automatic takeaway directly;

- creating optimal conditions for creating "lag" directly;

- creating optimal conditions for the trigger finger pressure point to act directly;

- creating optimal conditions for the short lead thumb to appear automatically directly;

- creating optimal conditions for minimizing any hands motion in a pivot-guided swing indirectly;

- creating optimal conditions for letting the early elbow plane in the downswing phase indirectly.



Last, but not least, I personally find it very interesting that the "biokinetical grip" may be used without NO SINGLE CHANGE for holding a putter, allowing the rotation of the neutral clavicle bones plane to lead the putting stroke. It is amazing how easier is to putt on a true arc taking the impact of the hands out and, simultaneously, how easy is to apply a correct force for the stroke. Besides, I cannot imagine anyting better than to have one and the same grip for all clubs, putter included.



Why the Biokinetic Grip is so helpful while:

a. the hands are not working paralelly to each other;

b. the lead hand is not parallel to the clubface.



My answer is very simple. Because the so-called "classic" golf swing theories never truly concentrated on biomechanics and because golfers blindly believe in "imperatives". I say there are no imperatives until they are verified through all possible methods and sciences. The answers are:

a. the so-called "parallel V's" theory is biomechanically not optimal for the reasons I've just described. To remind them:
- wrists cannot achieve its maximal potential in creating lag;
- wrists work paralelly to each other accentuating the primary motion (hinging-unhinging) that is hard, or even impossible, to control.

The importance of lag does not need to be underlined. But should not we ask yourselves why is that so many golfers flip when trying to hit the ball ? The answer is - because they want to hit the ball the farthest (it's the role of the subconscious mind) and because the CP/CF forces in a rotary movement + gravity help in releasing the clubface...and - because the wrist are set the way that unhinging is almost a must in such a scenario.

OTOH, the BG creates a scenario when one (lead) wrist cocks/uncocks while the other (rear) hinges unhinges; no matter if all other factors (CP/CF, gravity, rotary motion) exist, the possibility of losing the rear wrist hinge lag is much more limited, because the lead wrist motion is of secondary biomechanical importance and one won't be able to flip the RH wrist so much. Simply, the lead hand will be tending to deviate ulnarly (downcocking) and will create a natural limitation for a more powerful palmar flexion (unhinging) action of the rear wrist.




b. why the lead wrist should be parallel to the clubface ? to control its movement in so fast an action ? sorry, I don't buy it. Moreover, think what position should have the lead wrist in a correct rotary swing when both hips and upper body are open at impact in relation to the target line. Should the lead wrist be square to the target line or is it the clubface that needs to be square ? If the lead shoulder is open at impact - the LH palm should not be square to the body motion, what means it must be also open in relation to it (say, "delayed"). It is the clubface that should be square (OK, very slightly open at contact with the ball, ideally), therefore, the LH grip must not be parallel to it but in a stronger position on the grip.



Lastly, the question of offsetting the wrist/hands motion. We must remember that wrists are very mobile joints. They consists of many small bones that are practically impossible to control in a very rapid action. Therefore, it would be silly, IMO, to let them be influenced by so powerful forces as CP/CF or gravity - we should concentrate on finding obstacles that help in reducing such an influence. The Biokinetical Grip is one important obstacle to consider.


Here is the video about the Bio-K Grip with Mr.Hogan as the protagonist:





We shall present how to build correctly the Bio-K Grip in the part 2.

Wednesday, 14 April 2010

The Arms

This is the most complicated area of the golf swing to describe and to find automatism from biokinetical point of view. There are, at least, four main reasons that are responsible for this:


- humans are equipped with two arms that are "programmed" to act independently while their task is to act freely in the space;

- arms are equipped with a lot of muscles and several joints (especially wrist and fingers ones) that enable them to move almost in all possible directions and execute a huge variety of tasks;

- the only one link between the arm and the main body is the shoulder joint; moreover, both shoulder joints are distant from each other a significant way;

- elbow joints are built the way that makes it impossible to tie the forearms to each other during an action.



First, I want to stress that I have concluded that there is no real possibility (and, what is very important, there is no real need, in fact) to find limitations of the fingers, hands and the wrists that could be useful for our purposes. The only one very important role of the fingers and the hands is to hold the club the proper way and the rest is pure physics. It is time now to present the concept of nunchakoo and the role of angular momentum conservation rule (please bare with me, since I am not a physician and want to present it in a most friendly way).

Imagine that your forearm is one stick of a nunchakoo, while the club WITH HANDS ON IT is the second one. The wrists play the role of a chain linking both sticks. Now, according to the physical rule of angular momentum conservation, during a rotational movement of the main body, the momentum is constant in a closed system. Shortly, it means that if the velocity of the rotation is constant nothing changes in a perfect model. In the golf swing, after transition, the rotational velocity initially increases, then decreases before impact letting the club catch the hands, because the main goal is not to maintain the delay (lag) but to hit the ball. The whole trick is to find the proper moment of levelling the clubhead with the grip, or, other words, to find a proper moment for a bottom of the arc to happen. It is not the role of the wrists or hands to find it (although e.g. TGM school insist on "educating hands concept") because the timing would be a protagonist here. This is the role of the proper work of the legs, main body rotation and upper arms to prepare the position that would automatically find the correct moment in a due time without even thinking about it.

Please, understand correctly what I try to say. I am not trying to say that the concept of training wrists/hands is wrong - au contre, it is a great concept how to hit the ball properly. The human brain sees the action of ballstriking the way that we need to bring the ball airborne - this is a real katharsis for all flippers and bad shots. And it is not easy to fight any subconscious rules, but not that difficult. When one of my friends, an avid physician, explained me the momentum conservation rule, I have started to hit shots with very deep divots well after the ball so my clubhead even stopped in the ground for a milisecond. Thus, one either have to convince their brains to trust in the loft of the clubhead or to educate their hands. The only one minus is that wrists and hands cannot be trained enough well - and this is true, unfortunately, because we are not robots. It is much easier to leave it to the physics of our 3-D reality.

But, back to the merits - the angular momentum conservation rule is responsible for creating and maintaining lag when only one of our arms parts can play the role of the nunchakoo chain. The wrists are biomechanically born for this goal. CoG shift that enables to turn on the lead leg (i.e. CoG shift forward) makes the arms be in a correct position at impact - in front of the ball, if needed - if only the arms are subdued to the body turn. The upper stick of the nunchakoo (i.e. the forearms) follows the body turn and CoG shift letting the lower stick to catch it late enough.



The biggest problem is that we have two forearms that cannot be tied to each other, yet it would be the best if both arms worked as an unit. Unfortunately, it is not possible because of the distance between shoulders joints and the elbow joints build. The latter consist of three independent joints closed in one big joint - they are responsible for all the motions the elbow joint is able to make. For the simplicity, we concentrate on two planes of the elbow joints motion - bending/unbending and rotation.



In The Legs chapter i have said that the elbow joint is homologeous to the knee joint, yet there are some crucial differences between them. The first one is that the elbow joint (opposite to the knee joint) can rotate only when the arm is straight . The second one is that the elbow joints (also opposite to the knee joints) may and usually do work in different planes.



Let's deal first with the rotational aspect - a bent arm in elbow can rotate roughly 180 degrees with a fixed point of the elbow due to the forearm rotation; a straight arm in elbow can rotate almost 300 degrees (thus, the elbow joint can add more than 90 degrees), which is a huge difference, especially, when we think that the clubhead can be rotated the same huge amount. It says us that there is practically no possibility of find a biokinetical limitation that would make the arm movement automatic. But there is a chance - we have two arms and two elbow joints that work in different planes. It's a bliss, since one of them can limit the other one relatively easily. The right arm is bent in elbow at impact, therefore, it cannot rotate as much (or better said, it finds its limits in the motion earlier) as the straight left arm at impact. Moreover, there is a limit of the forearm turn in relation to the elbow joint depending on the grip - look at post-secret Hogan's setup position - his inside part of the right elbow is very well visible from the FO, while his right hand is on top of the grip in weak position. IMHO, he found the rotational limit of the forearm-elbow system just at setup and maintained it until the very impact. It would excellently explain how his right elbow drops down at transition - because it cannot do anything else if the main goal of the downswing is to keep the elbow-forearm system position fixed - at impact his elbow inside part is visible. Moreover, Hogan had both arms slightly bent at address what seemed to help him not to start the backswing with an overrotation of the elbow-forearm system in both arms.



The bending aspect is more tricky. It is much easier to obey the rule of keeping the distal parts perpendicular to the spine when both arms are straight. It also gives a much better feeling of both arms working in unisono. Lastly, although straight arms in elbows enable bigger rotation, sort of "blocking" both elbow joints takes them practically out of play - like a human was equipped with arms without elbow joints. This is what can be observed in Moe Norman's action to a degree - arms perpendicular to the spine "urging" to be straight as soon as possible at the downswing.

IMO, the weak point of this scenario is that the only one link of both distal parts to the main body are the shoulders joints that are too weak taking into account the length and the weight of the arms (+ the club). This may be the most evident proof why Norman was not a long hitter, although his brain made his pivot and arms work great together in synch. Lastly, it is worth stressing that Moe had a very strong grip of the right hand and not so strong of the left one (opposite to Hogan) that promotes having both inside elbow parts to work more parallelly to each other.



So, now we come to the second golden rule of biokinetics (first was treating about perpendicularity of the arms to the spine during the rotational motion), i.e. to link the upper part of the arms to the main body during the motion. It's dynamically possible only when the main body is in a open position at impact - since this is the only one position that can ensure the left upper part be pinned to the open chest while the right upper arm is, say, at the shirt seam. A square or a closer main body at impact would inevitably lead to the necessity of having both upper part of arms in the front of the body, which is equal to increased possibility of timing issues to happen - arms less subdued to the pivot.

It can be done both ways - to want to subdue the left arm first or the right one first, or both. It is much easier to let the lead arm be pinned to the chest via the turning main body (this is what the majority of rotary swingers do, me included until now); however, it would leave the right hand in a very weak position with the inside part of the elbow more facing the target (especially with the strong right hand grip). The right arm action solo brings a danger of thrusting both elbow joints (and, consequently, both arms) in the front of the body which is bad thing from a biokinetical point of view.

The golden means is to try to subdue both arms simultaneously - right elbow must go down and close to the hip (which is easy thing to do taking into acount the CoG shift onto the lead leg during transition) while letting the lead upper arm be pinned to the chest at impact. Hogan's right arm action (I call it the right elbow is searching the left one in order to be as close as possible to it) makes his left upper arm be away from the body at first but before impact it is already pinned to his turning and opening to the target chest. It appears to be easy while maintaining the afore-mentioned limit between forearm and elbow rotation - even me, with my body flaws, can do it now decenty to a degree.

Lastly, when Hogan described the famous concept of tieing both arms with having both elbows close to each other during the motion, he forgot to uncover the elbow joints on the picture. It is obvious that both elbows cannot be turned to each other with their inside parts but rather be perpendicular to each other.





I think it is useless to analyze the optimal elbows position at setup without referring it to the wrists positions. In order to find a limit at the end of the backswing one of the crucial thing from biokinetical point of view is the amount of forearm rotation available, if I may say this way.

If you e.g. combine a weak LH grip with elbow pointing out you will find it may lead easily to overrotation (moreover, can lead also to a too inside takeaway); if you combine it with elbow pointing back (to the pocket), your left forearm has already established a certain amount of preset rotation. The same rule applies to a strong LH grip - one should not combine this kind of grip with elbow pointing back since it may appear that the rotation will end too soon before backswing is completed.

Therefore, the whole trick is to find an optimal combination of the whole elbow-wrist system at setup.



RH elbow joint should always point back since the rear arm job is mainly to fold and not to rotate. This fact creates a double security limitation. Moreover, IMHO, the best scenario is if the RH grip is weak (as in case of Hogan) while having elbow pointing in (already presetted a clockwise forearm rotation) since it also prevents from a too inside takeaway via the right wrist hinge, as well as it eliminates the possibility of overrotation of the right forearm during the downswing.

Having analyzed a lot of post-secret Hogan's footages I noticed that his right hand grip was always in a weak position, while his LH grip was "moving" between weak and neutral ones. Together with this slight grip changes his left elbow position at setup also varied - from pointing back (especially with short clubs) to pointing more out (especially with a driver). I am sure he found a method of establishing an optimal amount of his left forearm preset rotation that enabled him to finish his backswing in a due time without even thinking about it.

Since we all are different individuals, I think it is the best to experiment with various combinations of elbow-wrist system positions at setup, especially as regards the lead arm. The right arm's role is not to disturb at the backswing and deliver a pivot guided power at the downswing.

The primary importance motion of a wrist is hinging-unhinging (dorsi and palmar flexions), while cocking-uncocking (ulnar and radial deviations) is, say, of secondary importance. You can easily see how much easier is to hinge than to cock the wrist as well as how much far away you can hinge (up to ca. 90*) than to cock (up to ca. 45*). This fact determines that if both hands are tied in a golf grip, and the directions of the motions of both wrists are just close to each other (left wrist cocks while right one hinges; although usually there is no straight 90* relation between them, it is close to it in a proper grip), the direction of the total movement will be rather determined by hinging, not by cocking.

A strong RH grip will cause the right wrist to hinge too much to the inside during takeaway and backswing then. A weak RH grip will cause the wrist to hinge more up on the correct backswing plane automatically, leading the direction of the LH wrist cocking also on the correct plane without the necessity of toying with forearm rotation.

Too bad I did not know it before - I would spare a lot of hours in search of an optimal takeaway and backswing.



Now, if the plane is correct, nothing prevents both wrist from finding their anatomical limitation at the top and achieving a great angle between forearm and shaft. Just it is "a hell of a wrist cock". Please also note that in such a situation, the club reaches the straight angle towards the forearm rather soon - that's why Hogan's shaft was perpendicular to the ground just when his forearms were parallel to the ground. Thus, he might easily shorten his backswing because it feels like you are already set much before the time when the shaft is parallel at the top. Moreover, post-secret Hogan could swing the club with a short LH thumb, what emphasizes it even more (it's anatomically easier to achieve a big wrist cock with a long thumb). He had much better control and he did not lose anything from his lag. Simple, huh ?



Lastly, in a ideal model, the grip of the LH should be perpendicular to the RH one, i.e. one should combine a strongish LH with a weakish RH, but it's difficult to do because of the fact that the RH grip is somehow determined by the position of the LH thumb on the shaft.

The Legs

Although a few sentences have already been written about arms, describing the legs action from the biokinetical point of view appears to be more logical as a consequence of the previous chapter about the main body. It is also much simpler to do since the legs are the base of the whole human body and the only link between us and the ground.


The evolution of species proves that the gravity is not such a huge obstacle to force to engage all distal parts with an aim to keep the main body safe, stable and balanced. A pair of "well-designed" legs is enough to enable us to make a huge variety of motions. If we look what is the main difference between us and animals (except Primates) we can see that our feet can be entirely used for a contact with the ground. This fact have pros and cons - the main advantage is that we do not usually need our arms to help us to move or maintain balance, the main minus is that we are not very flexible in a 3-D movement comparing to almost all mammals.

The impact of this fact is crucial when talking about a golf swing motion where the most important goal of the legs is to maintain balance (and not e.g. to jump or change the orientation of motion fastly). Our feet are a very solid base for the rest of the body, and, what is equally important, they are very sensitive for changes in the motion. They can be like this since the anatomy of a human foot enables to react immediately to the brain's signals with a very rich variety of actions (dorsiflexion, plantarflexion, abduction, eversion, inversion, supination, pronation, etc.) because the lower joint (malleolus=ankle) let the feet move practically in all possible directions. The good thing is that there sould be no special attention paid to the ankle joint and its limitation since the gravity and necessity of maintaining balance does it for us. It is more important to look at what feet are supposed to do (or, better said, how they should be placed) and what impact it may have on segments that are located further from the ground.

The other legs joint of huge importance is the knee joint which is, BTW, the biggest joint in the human body and is homologeus to the elbow joint in the arms, however, they both are acting differently as regards planes of motion. Simplyfying the topic, the knee joint can act in two independent planes - it can flex/extend as well as rotate. What is interesting, a two-axial joint always have the primary and secondary motion, i.e. one of the motions are much frequently used from biomechanical point of view.

In case of the knee joint, flexing and extending are the motion of the primary importance - but only in one direction - knees cannot be bent backwards. That is why the ankle joint is not located in the middle of the feet.

The lateral rotation is very limited (up to 30 degrees only) - and this fact is crucial for our golf swing motion since the knee rotation happens exactly in the same horizontal plane. Another fact worth mentioning is that flexing/extending action of the knee is strictly related to the foot motion, that means it can be subdued to a proper feetwork. I want to underline the word "feetwork", not "footwork" - the greatest ballstrikers never let put the work on only one foot practically until approaching impact (well, the truth is that if the stick is long enough and the stance very wide the rear foot is too far away from the CoG at impact and it is not entirely flat on the ground at impact).

Lastly, the hip joints, that are the true links between the main body and the legs. The fact that there are two of them plays a crucial role in all CoG shifts of the human body in action, as well as determines which of the two hip joints is the protagonist. When a main body equipped with two lower distal parts is turning and wants to do it effectively, it must act as if we have only one leg. Independent two joints are the obstacle in a turning motion and a bliss for a sway. This is why the primary thought of a golf beginner is to sway with the hips in order to gain power and not to put the vast majority of the weight of dynamically turning mass on one leg. Why ? because our brains see the ball flight as a linear motion (from the point where we are to the target). When the same beginner begins to believe in gaining power from rotation of the body, he instinctivelly places the CoG on one of the hip joints. Moreover, it is much easier to understand why it should be the lead hip joint, and not the rear one - the orientation of the linear movement is just this way. Combine the linear movement concept with conviction that rotation gives the true power and the effect will be a great CoG shift in a hip area. It is that easy, IMHO, and in a perfect accordance with the optimal hip area movement described in the previous section.



OK, now ad rem. The golf swing motion relies generally on turning the whole body back and forth. Thus, we need to find limitations in joints to ensure automatism in the whole motion. Since we already know that the main body should encounter the sum of small X-Factors it becomes obvious that it needs a stable base. Neither feet, nor knees should enable the rear hip slide back and lose the coil.

Therefore, the most important limitation that is to be found is to make impossible for the knee and ankle joint to move separately from the rest of the upper body. Unfortunately, the dominant motion of the knee joint happens in a perpendicular plane in relation to the orientation of the golf swing motion, and nothing can be done about it. That's why there are a lot of golfers (even the greatest ones) who squat down or up in certain moments of swing. It's inevitable in such a dynamic motion. Luckily, our brains are able to control it when focusing on the primary goal which is hitting the ball and not the ground. That is why casters (early release golfers) stand up before impact and that is why great golfers squat after transition in order to maximize the optimal velocity of the clubhead. Please also note that the small feet CoG shift reflects in the knee joint movement - the more is the weight set to the heel, the more the knee extends in a rotary motion, and viceversa.



Nevertheless, a lot can be done in another plane, i.e. in finding the limitation of the rotation in both knee as well as in ankle joints. Proper feet stance is crucial because there is a significant amount of friction between the sole and the ground. The more the feet is directed towards the target of the motion the more limit will be found in both joints. That's why Hogan moved his heel of the rear foot back, setting it at least perpendicularily to the target line - which move is well documented in a lot of films as well as in his books. It makes finding the limits of knee and ankle rotation very easy. When there is limit, there is no room left for screwing the motion. IMHO, it's enough, and although I follow the Sevam's thread carefully as a big Hogan fan, introducing another thought as e.g. screwing the foot into the ground is not necessary since it puts the focus on timing. The rear foot is "screwing" into the ground automatically when the knee rotation finds its limits because the foot cannot turn back due to the resistance. Therefore, in my opinion, presetting the torque does its job perfectly without necessity of thinking about it. Funny thing is that the knee joint rotates only when it is bent what would suggest that one should hit balls with straight legs...but such a swing would be deprived of power, thus, it is not a subject of the studies.

The left foot, as we know from "The 5 Lessons" should be flared and this concept is also biomechanically very sound. It allows to find the limit of rotation of the lead knee even faster than the rear one. The knee that cannot rotate further bends inwards what almost automatically makes the weight shift on a lead hip joint when the linear CoG shift happens. If the lead foot is put inward, instead flared, all tension in the knee and hip is lost. Moreover, the sum of small X-factors is being achieved properly when the lead hip "stays" early in the backswing allowing the rear shoulder find its limit without making the backswing too long and loose.

Lastly, it is to be pointed out that setting the weight in various patterns influences the limits. If a swing pattern requires setting more weight on a front foot, the rear foot needs to find its limit later in the motion because of the upper body position (mainly a necessary spine angle lateral bent when swinging back); thus, in such a situation, keeping the rear foot perpendicular or even slightly turned inwards is not a great thing. The same is true when, hypothetically, one needs to keep the majority of the weight on the rear part, but, as explained earlier, should not be discussed there because of the linear orientation of the swing motion.