In this post I am going to present my first draft version on how to biomechanically perform a hand couple induced release of PA#2. I have being thinking about this issue day-and-night for many days, and this is my first attempt to explain how I think that one should perform a hand couple-induced release of PA#2 from a "real life" biomechanical perspective.
Before I describe the major transformation of my thinking on how to release PA#2, let me recap how I previously recommended performing the downswing action.
I previously believed that swing power should be generated in a TGM swinging manner (lead arm swinging manner) where one uses a pivot-induced release of PA#4 followed by a passive release of PA#2. I wrongly presumed that the club would release automatically/naturally at ~P5.5 according to the law of physics called the D-Alembert principle. I believed that the lead wrist should not be manually released - either via i) an active left wrist uncocking action due to activation of the forearm muscles that ulnar-deviate the left wrist or ii) via push-pressure being applied by the right hand against the club handle at/near PP#3 (which is below the coupling point). I wrongly presumed that any push-pressure being applied by the right hand below the coupling point would invariably predispose to casting. To control the magnitude of the "physics-induced force" supposedly causing a passive PA#2 release action, I recommended the aiming point technique - where one would create a more U-shaped hand arc path for longer clubs and a more V-shaped hand arc shape for shorter clubs.
I now strongly disagree with my previous line-of-thinking because I now believe in the scientific validity of the following torque graphs.
Note that there is remarkable degree of consistency between touring pros, teaching pros and amateur collegiate golfers regarding the hand couple graph (red graph). They all apply a positive torque across-the-shaft starting at P4, which then increases in magnitude to ~P5 - P5.2. Then, the positive torque decreases between P5.2 => P5.5 before coming negative after ~P5.5. The degree of variance between different skilled golfers (amateurs versus pros) is very small. I contacted Dr. Kwon via e-mail to ask him a fundamental question-: How does one teach a student-golfer how to create that specific pattern of hand couple curves. He stated that one cannot teach a student golfer how to produce forces/torques on the club grip and he stated that any attempt to teach a student-golfer how to apply a hand couple torque during the downswing would ruin his swing. He stated that the correct hand couple torque patterns are simply the "effect" (end-result) of a "good" quality swing action. That reply was very unsatisfactory to me because it is very easy to assert that all the skilled golfers in his study had a "good" quality golf swing action. But, how does one teach a developing-golfer how to perform a "good" quality golf swing action? Dr. Kwon (like you and me) recognizes a "good" quality golf swing action when one sees it (eg. Adam Scott's or Justin Rose's golf swing action), but Dr. Kwon could offer no practical advice on how to teach it from a biomechanical perspective. I therefore decided that I needed to solve this problem by myself without any useful advice from Dr. Kwon or Sasho MacKenzie.
I basically needed to solve the problem of how a golfer should apply a positive hand couple torque (particularly involving a positive push-pressure by the right hand against the aft side of club handle below the coupling point) between P4 => P5.5 without inducing casting. I also had to solve the problem of how does one gradually decrease the positive hand couple torque between P5.2 and P5.5 so that it becomes negative after P5.5 in a consistent/repeatable manner.
Here is the first draft version of my biomechanics-based explanation (which is preliminary, incomplete and open to continuous revisions as I continue to think more deeply about this topic).
Here is Dr. Kwon's image showing a hand couple.
Note the direction of the arrows showing the forces being applied to the grip during a positive hand couple event - the left wrist must be trying to actively uncock while the right hand is actively pushing agains the aft side of the grip below the coupling point thereby applying a positive "force-across-the-shaft" force. One could understandably think that the application of those positive hand couple torques would induce casting and a premature release of PA#2, which does not actually happen in a skilled golfer's early-mid downswing action. So, how can I solve this problem in terms of rational biomechanical advice?
First, consider what Brian Manzella thinks is the correct way to perform a "force-across-the shaft" action with the right arm/hand.
Note that he does not want the right palm to simply push against the shaft because that will simply move the whole clubshaft forwards without any angular rotation happening about the coupling point (mid-point between the hands). He actually wants to induce a "rotation about the coupling point" phenomenon where there is angular rotation about the mid-point between the hands. Think about that "rotation about the coupling point" scenario - and realise that a rotation about the coupling point will only happen if the club is stationary, or near stationary, and if the left hand is pulling back on the club handle at the same time as the right palm is pushing against the club handle below the coupling point (thereby producing a hand couple-induced angular rotary motion of the clubshaft about the midpoint between the hands).
Here is an amateur golfer who tried to follow Brian Manzella's advice on how to apply a Manzella-type of "positive torque across-the-shaft" golf swing action using the right arm.
Note that he is casting (= inducing an early release of PA#2) between image 1 and image 2. Why is it happening? Note that he is using an immediate right arm straightening action combined with a punch elbow motion of the right elbow (where the right hand prematurely bypasses the right elbow which is not being actively driven groundwards due to an active right arm adduction maneuver) and he is also allowing his right wrist to straighten during that same time period. That type of biomechanical action will produce an excessive "force-across-the-shaft" below the coupling point and it will induce premature left wrist uncocking (premature release of PA#2).
By contrast, consider Dustin Johnson's downswing action between P4 => P5.5.
Image 1 is at P4, image 2 is at P5 and image 3 is at P5.5.
Most importantly, note how DJ is moving his right arm between P4 and P5.5 from a biomechanical perspective - he is actively adducting his right arm while maintaining an unchanged degree of right elbow bend and an unchanged degree of right wrist dorsiflexion, and he is using a pitch elbow motion where the "right elbow leads the right hand" (note how the right elbow is visible below the left arm at P5).
Try an experiment at home - mimic DJs right arm action of actively adducting the right upper arm, while keeping the right forearm angled back, without a golf club to get a "feel" of the right arm's motion - while making sure that you keep the right elbow bend angle unchanged and the degree of right wrist dorsiflexion/upcocking unchanged. During this active right upper arm adduction motion, you should note that there is a limit to the amount of potential force that the right hand can potentially apply in a "force-across-the-shaft" direction no matter how actively one adducts the right upper arm - as long as i) one keeps the right elbow bend unchanged and ii) as long as the "right elbow leads the right hand" and iii) as long as one keeps the right wrist fully dorsiflexed/upcocked. Then, try that same right arm motion together with the left arm and a golf club while allowing the left hand to pull the club handle very fast downwards between P4 => P5.5 ( as seen in DJ's P4 => P5.5 swing action) while making sure that you simultaneously try to actively adduct the right upper arm at a very fast speed so that the right hand travels as fast as the left hand. When the two hands are moving very fast downplane between P4 => P5.5, then it becomes nearly impossible to apply excessive "force-across-the shaft" with the right hand (if you use the correct right arm motion) and you should "feel" that the amount of "force-across-the-shaft" being applied by the right hand is only a little bit more than the amount that is needed to combat the negative torque produced by the MofF (due to the left hand pulling the club down the hand arc path and where the MoF causes the clubshaft to rotate clockwise).
At the same time as you perform the above experimental motion with a golf club (mimicing DJ's downswing action), try to actively uncock the left wrist (as shown in that Kwon diagram). What you should discover is that you cannot possibly uncock the left wrist if the left hand is traveling very fast between P4 => P5.5 where it reaches its maximum hand speed at P5.5 - even though the left wrist is deliberately applying a positive left wrist uncocking torque in a hand couple motional manner. Think of Jack Nicklaus' advice of "releasing the club from the very start of the downswing" and try to deliberately induce an early PA#2 release action while moving your two hands very fast down the hand arc path between P4 => P5.5. You should discover that it is impossible to release PA#2 prematurely if you are moving your two arms very fast in the manner that I have described. What you should "feel" is a "force-across-the-shaft" torque being applied by the two hands at the level of the club handle as they work conjointly as a positive hand couple between P4 => P5.5 - and the key biomechanical factor that prevents any early left wrist uncocking phenomenon between P4 => P5.5 is the fact that your two hands are moving very fast between P4 => P5.5 due to a very efficient release of PA#4 combined with a very efficient right arm adduction maneuver. You should "feel" that the hand couple-induced "force-across-the shaft" torque being applied to the club handle peaks between P5 => P5.2 if you are performing all the correct biomechanical actions at the correct speed.
Once you have learned how to efficiently apply a positive hand couple torque between P4 and P5.5, you have to learn how to convert to acquiring a negative hand couple torque after P5.5.
The key biomechanical factor that allows the positive hand couple torque action to automatically/naturally decrease between P5.2 - P5.5, and then become negative after P5.5, is the slowing down of the degree of "force-across-the-shaft" being applied by the right hand during that mid-downswing time period. What would cause the right hand's ability to produce a positive "force-across-the-shaft" to automatically/naturally diminish after P5.5 - without any conscious thought being required by a golfer in order to deliberately slow down the speed of motion of the right hand in any artificial/unnatural manner?
Let's go back to these capture images of Dustin Johnson's downswing action between P4 => P5.5.
Note that there is no impedance to the downward motion of his left arm (induced by the release of PA#4) between P4 and P5.5. Likewise, there is no impedance to his speed of right arm adduction between P4 and P5.5 that allows his right hand to travel at the same speed as his left hand (even though he maintains an unchanged bent right elbow).
However, note that his right upper arm becomes fully adducted against the right side of his torso at P5.5, and it now becomes potentially impeded in terms of further adduction after P5.5.
Note what happens between P5.5 and P6.5 in DJs driver swing action.
Note how his right arm stops adducting between P5.5 and P6.5. while his right hand still moves downplane along the hand arc path (togther with his left hand), but his right hand's targetwards motion is mainly due to a passive right elbow straightening action combined with a pitch elbow motion (stone-skipping motion) of his right arm.
Consider this right hand motion between P5.5 => P6.5 in greater detail by viewing the motion of the right elbow and right hand between P5.5 => P6.5 in a skilled golfer's driver swing action.
The red path represents his hand arc path.
Image 1 is at P5.5. I have drawn a small circle yellow over his right antecubital fossa to show the position of his right elbow at P5.5 when his right upper arm is fully adducted against the right side of his torso. I have drawn a small green circle over his right hand.
Image 2 is at P6. I have drawn a small blue circle over his right hand. Note that his right elbow has moved very little targetwards between P5.5 => P6, but his right hand has moved a lot more down the hand arc path as he passively straightens his right elbow.
Image 3 is at P6.5. I have drawn a small white circle over his right hand. Note that his right elbow has moved very little targetwards between P6 => P6.5, but his right hand continues to move targetwards due to his continuing right elbow straightening action that is combined with a pitch elbow motion (stone-skipping motion) of his right arm (where the right hand now bypasses the right elbow in a stone-skipping manner).
It is my "belief" that the right elbow straightening action seen between P5.5 => impact in a skilled pro golfer's driver swing action is passive, and that it is not active (as would happen in a competitive wood-chopper's chopping action or a TGM hitter's active release of PA#1).
If the motion of the right hand down the hand arc path between P5.5 => P7 is more passive, then it could explain why the right hand's "force-across-the-shaft" lessens a lot after P5.5.
Here is an image from Koike's paper showing the kinetic results collected from a single pro golfer using his instrumented grip handle.
Note how the "force-across-the-shaft" being applied by the trailing hand (right hand) decreases near P5.5 and then becomes negative after P5.5, and also note that the right hand couple's ability to generate a moment (torque) disappears after P5.5.
In summary, I think that it is natural/automatic for the right hand to produce less "force-across-the-shaft", and a lesser moment around the coupling point, if the active right arm adduction action that actively drives the right hand downplane dramatically decreases near/at P5.5 and if the right elbow only passively straightens between P5.5 and impact.
I have being experimenting with this positive => negative right hand "force-across-the-shaft" phenomenon in my personal golf swing action. I start my downswing with an active release of PA#4 combined with an active right arm adduction maneuver while simultaneously trying to maximise my hand couple torque (while keeping an unchanged bent right elbow and an unchanged bent right wrist). I then try to "feel" my right arm adduction maneuver slow down dramatically near/at P5.5 when my right arm is fully adducted against the right side of my torso, and I then try to "feel" my right elbow straightening passively after P5.5. However, I continue to actively pull my left hand down the hand arc path to well beyond P5.5 to ensure that I maintain a sufficient "net force" (linear force that is directed down the hand arc path) that will create enough MofF to continue to accelerate my clubhead all the way into impact. Using this hand couple technique, I am now releasing PA#2 more assertively and I am less likely to reach impact with an incomplete release of PA#2, where there is too much forward shaft lean and an open clubface (that predisposes to push-sliced shots). I still have to think a lot more about the biomechanics/mechanics happening during the P5.2 => P6.5 time period when the positive hand couple first progressively lessens in magnitude and then becomes negative, so that I can better understand what biomechanical/mechanical factors affect its pattern. I have already discovered when experimenting that if I allow my right arm adduction manuever to continue unimpeded after P5.5 so that my right elbow gets too far ahead of my right hip joint area that I lose the ability to convert from a positive right hand couple motion to a negative right hand couple motion in a timely manner, and I don't "feel" the club whip passed my hands due to an efficient release of PA#2. I need to understand much more about how to passively pivot my right forearm/hand around the fulcrum point of a right elbow that is "fixedly" positioned close to my right hip joint area between P5.5 and impact. I also have a lot more to mentally explore, and a lot more to mentally understand, when it comes to learning how to best convert from having a positive hand couple at P5.2 - P5.5 to then having a negative hand couple after ~ P5.5, but I certainly enjoy the "feel" of using an active hand couple-induced release of PA#2, which "feels" much more efficient than my previous TGM-style passive PA#2 release action, which was too passive and often unpredictably inefficient.
Jeff.