What effect does left wrist bowing, or cupping, have?

[imperfectgolfer]

I have produced a 55 minute video on topics related to the effect of left wrist bowing, or cupping, at the end-backswing position on the clubface orientation and I have discussed the compensatory moves needed during the downswing in order to get a square clubface by impact.

This video was produced on my condo unit's outdoor deck at sunrise on what was supposed to be a cloudy morning. Unfortunately, the sun broke through the clouds after I started filming and the sunlight shone across my deck causing the video to become too contrasty, and too "washed-out". I apologise for the poor quality of the video. To view the video at the maximum level of detail, set your you-tube display settings to the highest resolution that your display monitor is capable of producing and view in "full screen" mode.

Here is a brief summary of the topics that I discussed during the 55 minute video-:

i) Between the 0:00 - 10:47 minute time point of the video, I discussed (after an initial introduction) the LAFW concept and how the clubface cannot get too open during the backswing if the LAFW is intact and if the clubshaft is continously "on-plane". The clubface can only become too open during the backswing action if the left forearm over-pronates resulting in an off-plane clubshaft motion. I also discussed why I never use the ground as a reference point for deciding whether the clubface is open or closed at the end-backswing position.

ii) Between the 10:47 - 22:01 minute time points of the video, I discussed the "Dustin Johnson move" where I demonstrate that when Dustin Johnson bows his left wrist he angles the clubshaft to a "laid-off" position at his end-backswing postion, which means that he has disrupted his intact LAFW and caused the clubshaft to become off-plane. I then demonstrated that because he retains roughly the same degree of left wrist bowing during his entire downswing, he will arrive at the P6.5 position with a clubshaft that is angled backwards-and-inwards relative to his left forearm and that causes the clubface to be more open relative to the ball-target line. Therefore, to acquire a square clubface by impact, he needs to use an additional amount of left forearm supination - relative to another professional golfer (eg. Keegan Bradley) who also uses a moderately strong left hand grip, but who doesn't bow his left wrist.

Here is a link to a review paper where I describe the "Dustin Johnson move" in much greater detail.

perfectgolfswingreview.net/DJMove.html

iii) Between the 22:01 - 38:41 minute time point of the video, I discussed the "Reverse Motorcycle move" which many golf instructors incorrectly think is the same phenomenon as the "Dustin Johnson move" because it incorporates the biomechanical phenomenon of left wrist bowing. However, the "Reverse Motorcycle move" (which is also called the "Motorcycle move" or the "twistaway maneuver") is actually due to a finger torquing action (due to activation of the flexor digitorum muscles in the left forearm) that twists the clubshaft counterclockwise around its longitudinal axis, and any left wrist bowing is a secondary effect reflective of a large amount of twistaway action. I also demonstrated how the clubface-closing effect of the twistaway phenomenon dissipates in the later downswing as the clubshaft reaches closer to impact due to the outward/centrifugal pull forces generated by a fast-releasing club. Thirdly, I also demonstrated how a golfer cannot use a larger amount of body rotation in order to close the clubface and thereby avoid having to use a PA#3 release action (which is due to left forearm supination) in the later downswing. Therefore, in conclusion, it is a real life" fact that the use of the "Reverse Motorcycle move" combined with a larger amount of body rotation does not decrease the amount of left forearm that has to happen during the late downswing's PA#3 release action (for a given level of left hand grip strength).

Here is a link to a review paper where I describe the "Motorcycle move" in great detail.

perfectgolfswingreview.net/MotorcycleMove.html

iv) Between the 38:41 - 48:21 minute time point of the video, I discussed the effect of left wrist cupping at the end-backswing position on the clubface orientation and I demonstrated what effect that left wrist cupping phenomenon would have with respect to the clubshaft/clubface as the club gets closer to impact presuming that the golfer retains the same degree of left wrist cupping during the downswing.

v) Between the 48:21 - 53:47 minute time point of the video, I discussed the role of right forearm pronation during a PA#3 release action. If optimally performed, a right forearm pronatory motion happening in the later downswing can synergistically assist the left forearm in performing an efficient grip roll motion during the PA#3 release action. However, if the degree of right forearm pronation is excessive (relative to the degree of left forearm supination) it will likely result in left wrist breakdown and left wrist circumduction through impact.

Jeff.

[imperfectgolfer]

See this video by Tyler Ferrell that was just published on June 8th 2018.





Here are my comments that I posted in response to Tyler's incorrect claims.

Tyler's mental concept of the "motorcycle move" has expanded to a point that he now applies it to ALL golfers who have a bowed left wrist at any time point in their swing action - even if the clubface is not closed relative to the back of the left hand.

In his "Stock Tour Swing" book he has the following images showing the "motorcycle move".





Image 1 shows that the clubface is not closed relative to the back of his left hand and watchface area of his left lower forearm when he is at the end-backswing position. At the end-backswing position he has an intact LAFW where the clubshaft is straight-line-aligned with his left arm and where the clubface is straight-line-aligned with the back of his GFLW and watchface area of his left lower forearm.

Image 2 and image 3 show him performing the "motorcycle move" where he is twisting the club handle in his left hand secondary to activation of the flexor digitorum profundus muscle to his left hand's 3rd, 4th and 5th fingers and that causes the club handle to be twisted counterclockwise. The simultaneous bowing of his left wrist is a secondary effect due to the significant muscular activation of his finger flexor muscles (flexor digitorum profundus muscles) - note how his left hand's knuckles are curled under and note how the clubface closes relative to the clubhead arc and also relative to the back of his left hand.

That represents a "true" motorcycle move" action, which I have described in the following short review paper - perfectgolfswingreview.net/MotorcycleMove.html

Tyler incorrectly claims that Dustin Johnson is using the "motorcycle move" simply because he has a bowed left wrist. However, Dustin Johnson does not twist the club handle counterclockwise when bowing his left wrist and his clubface does not close more relative to the back of his left hand, or relative to the clubhead arc. In fact, Dustin Johnson has to use MORE than the usual amount of left forearm supination during his late downswing's PA#3 release action in order to get a square clubface by impact - compared to Keegan Bradley who uses an equally strong (3-knuckle) left hand grip as Dustin, but Keegan Bradley does not bow his left wrist and he therefore uses the standard amount of left forearm supination during his PA#3 release action (for a golfer who uses a 3-knuckle left hand grip).

I have described the "Dustin Johnson move" in the following review paper where I compared him to Keegan Bradley - perfectgolfswingreview.net/DJMove.html

Tyler incorrectly claims that Rory Sabbatinni is performing the "motorcycle move" in his late downswing simply because he converts from having a cupped left wrist at P6 to having a bowed left wrist at impact. However, it is impossible to close the clubface via a finger-torquing (club handle twisting) maneuver in the late downswing because the flexor digitorum muscles are being stretched by the outward/centrifugal pull of the releasing club between P6.5 and impact.

Here are capture images of Rory Sabbatinni's late downswing between P6 and impact.





Image 1 shows that Rory Sabbatinni has a GFLW (slightly cupped left wrist) at P6 and that he then has a bowed left wrist at impact (image 2). Note that his clubface is not closed relative to the back of his left hand, or the watchface area of his left lower forearm, at impact which means that any clubface-closing effect secondary to a "motorcycle move" cannot possibly be present. Note that Rory Sabbatinni has squared his clubface between P6 and impact in the standard manner - by using a PA#3 release action (which is biomechanically due to left forearm supination).

Tyler's claim that Henrik Stenson is using the "motorcycle move" at some time point in his early-mid downswing between P4 and P6 is irrational and unsupported by the "evidence". Henrik Stenson uses an intact LAFW/GFLW swing technique and he never closes the clubface relative to the back of his left hand, or the clubhead arc, between P4 and P6 by twisting the club handle counterclockwise while simultaneously bowing his left wrist.

Here are capture images of Henrik Stenson's downswing.





Image 1 shows Henrik Stenson at his end-backswing position with an intact LAFW and GFLW. Note that the clubface is straight-line-aligned with the back of his GFLW and watchface area of his left lower forearm and that alignment is expected because he uses a neutral left hand grip.

Image 2 is at P5. Note that he still has an intact LAFW and GFLW and that his clubface is still parallel to the back of his GFLW and watchface area of his left lower forearm. Note that the clubface is not closing relative to the clubhead arc.

Image 3 is at the P5.5 position. Note that he has an intact LFFW and a GFLW and the clubface is not closing relative to the back of his GFLW or the clubhead arc. There is zero evidence that he is using the "motorcycle move" (as seen in the previously posted images from Tyler Ferrell's "Stock Tour Swing" book where the clubface closes significantly relative to the clubhead arc and the back of the left hand secondary to a finger-torquing action that is the biomechanical basis of the "motorcycle move").

Image 4 is at P6.2 where he still has an intact LFFW and GFLW and where the clubface is still parallel to the back of his GFLW (which has rotated counterclockwise to a small degree due to the fact that Henrik Stenson is starting to supinate his left forearm).

I demonstrated the difference between a "motorcycle move" swing action versus an intact LAFW/GFLW swing action (which Henrik Stenson uses) in the following 55 minute video - perfectgolfswingreview.net/leftwristbowing.html

Jeff.

[imperfectgolfer]

Another comment that I have added to Tyler Ferrell's video on the "motorcycle move".

Tyler incorrectly claims that Justin Thomas uses the "motorcycle move" (which is a clubface-closing maneuver due to a finger torquing action) in his downswing action. However, that claim is not true! Justin Thomas actually uses the biomechanical maneuver called "combined early left forearm supination + left wrist palmar flexion) and here is the proof.

Here are capture images of Justin Thomas' early-mid downswing action.





Image 1 is at the P5 position. Justin's left wrist is minimally palmar flexed and that converts his GFLW (geometrically flat left wrist) to an AFLW (anatomically flat left wrist). Note that the clubface is not closed relative to the clubhead arc and it is parallel to the back of his AFLW. Although one cannot see his left lower radial bone (just above the left wrist crease), his left forearm has to be pronated at that position in order to allow his clubshaft to lie along the inclined plane (swingplane).

Image 2 is at the P5.5 position. Note that his left wrist is significantly bowed and that his left forearm is now more supinated (which causes his left lower radial bone to be rotated more counterclockwise relative to his left antecubital fossa) and that it causes his clubface to be tilted to a slightly more closed position (relative to the clubhead arc). That combination of two biomechanical movements is called the "combined early left forearm supination + left wrist palmar flexion" maneuver (and it is used by many pro golfers like David Toms, Gary Woodland, Rory Sabbatinni and Ben Hogan).

Image 3 is at the P6 position. Note how much more supinated his left forearm is compared to his P5.5 position. However, note that the clubface is vertical and still significantly open to the clubhead arc. That means that JustinThomas still has to perform a clubface-closing maneuver in his later downswing between P6 and P7 in order to get a square clubface by impact. Justin uses the standard clubface-closing maneuver in his later downswing (which is called a PA#3 release action in TGM terminology and it biomechanically secondary to left forearm supination) in order to get a square clubface by impact. Here is the proof.

Capture images of Justin Thomas' late downswing action.





Image 1 is at P6.15. Note that although Justin Thomas started his left forearm supination earlier between P5.5 and P6.15, his left forearm is still pronated (relative to his left antecubital fossa) and that the back of his left hand is facing the ball-target line. His clubface is still significantly open relative to the clubhead arc and the ball-target line.

Image 2 is at P6.7. Note that he has significantly supinated his left forearm and that the back of his left hand is rotated more counterclockwise (relative to his left antecubital fossa and relative to the ball-target line) - and this represents his release of PA#3, which causes the clubface to close relative to the clubhead arc. However, his clubface is still partially open relative to both the clubhead arc and ball-target line.

Image 3 is just past impact. Note how much he has supinated his left forearm between P6.7 and impact and that causes the back of his left hand to face the target at impact. Note that his clubface is square to the clubhead arc and ball-target line at impact, and that his clubface is parallel to the back of his AFLW. Note that his left wrist is not bowed at impact and his clubshaft is straight-in-line with his left arm. The left wrist bowing that happened during his "combined early left forearm supination + left wrist palmar flexion" maneuver has disappeared and its temporary presence did not decrease the total amount of left forearm supination that Justin Thomas needed to use in his late downswing in order to get a square clubface by impact.

Note that Justin Thomas had to use a lot of left forearm supination between P5.5 and impact in order to get a square clubface by impact, and that is fully expected because he uses a weak left hand grip. Note that his use of a "combined early left supination + left wrist palmar flexion" manuever between P5.5 and P6.5 did not decrease the total amount of left forearm supination he needed to perform in order to get a square clubface by impact. Note that Justin Thomas never used the "motorcycle move" maneuver at any time point during his downswing, which would cause the clubface to become closed relative to the back of his left hand (secondary to a finger-torquing action that twists the club handle counterclockwise).

Jeff.

[dubiousgolfer]

Dr Mann - I think your analysis and videos should highlight some of the flaws in TF's recommendations on doing this 'motorcycle move' . Just get the feeling that 3D analysis data (although generally useful) is being misinterpreted to package/sell specific golf instruction concepts without rigorous evidence to back it up. Maybe pressure sensors on the lead fingers and the use of Electromyography in the lead forearm muscles would provide better data and conclusions.

With regards Sabbatini's cupped to bowed wrist from P6-P7 , I noticed that during that period, he has more secondary tilt and that his shoulder has moved back away from the target. The shoulder joint has suddenly changed direction (quite acutely) with respect to the initial direction of the swinging lead arm/club, therefore couldn't the inertia of the club cause the lead wrist to bow as a secondary effect?

[imperfectgolfer]

Jun 10, 2018 9:03:11 GMT -5 dubiousgolfer said:

Dr Mann - I think your analysis and videos should highlight some of the flaws in TF's recommendations on doing this 'motorcycle move' . Just get the feeling that 3D analysis data (although generally useful) is being misinterpreted to package/sell specific golf instruction concepts without rigorous evidence to back it up. Maybe pressure sensors on the lead fingers and the use of Electromyography in the lead forearm muscles would provide better data and conclusions.

With regards Sabbatini's cupped to bowed wrist from P6-P7 , I noticed that during that period, he has more secondary tilt and that his shoulder has moved back away from the target. The shoulder joint has suddenly changed direction (quite acutely) with respect to the initial direction of the swinging lead arm/club, therefore couldn't the inertia of the club cause the lead wrist to bow as a secondary effect?

I thought that I have already stated that there is no value to the "motorcyle move" in my recent video. What more do I need to add?

I found Tyler's 3-D data on left wrist flexion/extension of no value.

I cannot understand how pressure sensors on the lead fingers can be helpful because they cannot differentiate between a firm left hand grip (without club handle twisting) versus a firm left hand grip grip that is producing a "motorcyle move" action with a clubshaft twisting effect. EMG of the lead forearm muscles will also not likely provide useful information because it cannot differentiate between isometric versus isotonic actions, and a firm left hand grip may produce an isometric measurement of a finite magnitude in the left forearm's flexor digitorum profundus muscles - but it cannot identify whether a clubface-closing effect is present due to a finger-torquing action.

I think that left wrist bowing that happens between P6 and P7 is most likely to be due to the left arm moving targetwards with a certain amount of force/energy combined with a certain degree of activation of the left wrist/finger flexor muscles - in the presence of inertia due to a lagging club. I cannot understand why any backward motion of the left shoulder socket in the later downswing will produce left wrist bowing.

Jeff.

[dubiousgolfer]

Jun 10, 2018 16:26:17 GMT -5 imperfectgolfer said:

Jun 10, 2018 9:03:11 GMT -5 dubiousgolfer said:

Dr Mann - I think your analysis and videos should highlight some of the flaws in TF's recommendations on doing this 'motorcycle move' . Just get the feeling that 3D analysis data (although generally useful) is being misinterpreted to package/sell specific golf instruction concepts without rigorous evidence to back it up. Maybe pressure sensors on the lead fingers and the use of Electromyography in the lead forearm muscles would provide better data and conclusions.

With regards Sabbatini's cupped to bowed wrist from P6-P7 , I noticed that during that period, he has more secondary tilt and that his shoulder has moved back away from the target. The shoulder joint has suddenly changed direction (quite acutely) with respect to the initial direction of the swinging lead arm/club, therefore couldn't the inertia of the club cause the lead wrist to bow as a secondary effect?

I thought that I have already stated that there is no value to the "motorcyle move" in my recent video. What more do I need to add?

I found Tyler's 3-D data on left wrist flexion/extension of no value.

I cannot understand how pressure sensors on the lead fingers can be helpful because they cannot differentiate between a firm left hand grip (without club handle twisting) versus a firm left hand grip grip that is producing a "motorcyle move" action with a clubshaft twisting effect. EMG of the lead forearm muscles will also not likely provide useful information because it cannot differentiate between isometric versus isotonic actions, and a firm left hand grip may produce an isometric measurement of a finite magnitude in the left forearm's flexor digitorum profundus muscles - but it cannot identify whether a clubface-closing effect is present due to a finger-torquing action.

I think that left wrist bowing that happens between P6 and P7 is most likely to be due to the left arm moving targetwards with a certain amount of force/energy combined with a certain degree of activation of the left wrist/finger flexor muscles - in the presence of inertia due to a lagging club. I cannot understand why any backward motion of the left shoulder socket in the later downswing will produce left wrist bowing.

Jeff.
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Dr Mann

The 'should' in my first comment meant in the 'past' tense.

With regards grip pressure sensors, I've seen this graph ( link below) on the 'Sandtrap'  forum which shows some average grip pressure throughout the swing between PGA Pros vs amateurs . If a golfer was using 'Twistaway' somewhere between P4  and P5  and applying enough to cause a secondary palmar flexion, which is then retained all the way to impact , wouldn't there be a 'spike'  in grip pressure between P4 - P5  and no appreciable rate of change into impact?   However, if your opinion is correct, that 'twistaway'  diminishes because of increase in CF forces , then shouldn't there be a dip after release into impact?

thesandtrap.com/gallery/image/616-grip-pressure/


Yes , it seems that EMG cannot distinguish between Isometric and Isotonic contractions , so maybe another option would be to use 'electrooptical muscle contraction sensors' .

Regards
DG

[imperfectgolfer]

I don't think that there will necessarily be a dip in grip pressure readings between P6 and P7 if the twistaway's clubface-closing effect disappears because the golfer may still be applying a lot of grip pressure between P6 and P7 even if the club-handle twisting effect of the twistaway maneuver is significantly reduced due to the outward/centrifugal release of the club.

I personally find the results of grip pressure studies too confusing to understand. I could never learn anything useful from those studies.

See the Komi/Roberts study - citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.923.7343&rep=rep1&type=pdf

or here - www.researchgate.net/publication/28577829_Measurement_and_analysis_of_grip_force_during_a_golf_shot

Here is another link to the abstract of a grip pressure study by Langlais - www.ncbi.nlm.nih.gov/pubmed/25122996 . I have the full text.

Jeff.