Revised downswing chapter

[imperfectgolfer]

I have revised my downswing chapter.

See - perfectgolfswingreview.net/downswing.htm

This is my 4th version and it contains many new insights regarding golf swing biomechanics/mechanics compared to my 3rd version, which was written 9 years ago.

I will still be adding more subtopics to topic number 8 during the next few months.

Error-correction suggestions will be appreciated.

Jeff.

[dubiousgolfer]

Dr Mann

I was reading this section below:

"Note that his trail wrist is markedly bent back (extended) at his P6.2 position (image 1) and that it is far less bent back at his P7 position (image 4), which means that he is straightening his right wrist during his PA#3 release action. While he is moving his trail wrist in a straightening (palmar flexing) direction, he is also moving his trail wrist in a radial direction and the combination of those two wrist movements produces a circumductory roll motion of his trail wrist, which allows him to continuously keep his trail palm facing his lead palm during his PA#3 release action (while his trail forearm simultaneously becomes less supinated)."

You gave an example using DJ




But couldn't DJ still retain a supinated forearm by slightly more protraction of his right scapula from P6.5 -P7 ? Wouldn't this also allow his palm to face the lead palm approaching impact?

DG

[imperfectgolfer]

I don't understand how an increased degree of right scapula protraction can affect the roll motion of the right palm.

Jeff.

[dubiousgolfer]

Feb 26, 2021 22:46:39 GMT -5 imperfectgolfer said:

I don't understand how an increased degree of right scapula protraction can affect the roll motion of the right palm.

Jeff.

Apologies, I have made an anatomical error as  I was trying to explain the movement as shown in the video below and it seems to be a contraction of the right 'pectoralis minor'. 

Wouldn't that movement , an almost sliding of the shoulder girdle down and slightly around the front of the ribcage,  avoid the need for internal rotation of the humerus (or any pronation of the forearm) while being able to keep the right palm facing the left palm? Could DJ be contracting that muscle between images 2 and 3?



DG

[imperfectgolfer]

If the right elbow can slide in front of the right hip area in the mid-late downwswing and allow the right humerus to remain externally rotated for longer - secondary to more scapula protraction - it will make it easier to keep the right forearm supinated between P6 => P7. However, it does not determine whether the the right palm's counterclockwise motion between P6 =< P7 is mainly due to right wrist circumduction when the right wrist partially straightens or mainly due to a decreasing amount of right forearm supination.

Jeff.

[dubiousgolfer]

Dr Mann

Many thanks .

I'm also still a bit doubtful about SMK's passive torque concept which you mentioned in your article .

In his own research article he conducted a Sim 3 experiment with the clubshaft travelling on the same plane as the lead arm but then actively switching on a 'lead forearm supinatory torque generator' about 0.16s into the downswing. This resulted in a square clubface at impact but 22% increase in clubhead speed compared to his passive torque experiment (Sim1 where the clubshaft plane was set under the lead arm plane with forearm generator switched off).

He then went on to mention the following :

a. "which indicates as to how much active rotation of the forearm from a muscular torque can contribute to clubhead speed".
b. "These two Sim3 and Sim5 simulations will most closely represent the coordinated downswings of actual golfers." (Sim5 was exactly like Sim3 but with a steeper left arm plane).


The question is do golfers actually use any active forearm supination for release of PA3# to increase clubhead speed, especially when there is a moderate PA3 angle? I understand that you think PA3# is a club squaring power accumulator but his experiment proved that it could be a source of clubhead speed.

DG

[imperfectgolfer]

Feb 27, 2021 12:05:31 GMT -5 dubiousgolfer said:

Dr Mann

Many thanks .

I'm also still a bit doubtful about SMK's passive torque concept which you mentioned in your article .

In his own research article he conducted a Sim 3 experiment with the clubshaft travelling on the same plane as the lead arm but then actively switching on a 'lead forearm supinatory torque generator' about 0.16s into the downswing. This resulted in a square clubface at impact but 22% increase in clubhead speed compared to his passive torque experiment (Sim1 where the clubshaft plane was set under the lead arm plane with forearm generator switched off).

He then went on to mention the following :

a. "which indicates as to how much active rotation of the forearm from a muscular torque can contribute to clubhead speed".
b. "These two Sim3 and Sim5 simulations will most closely represent the coordinated downswings of actual golfers." (Sim5 was exactly like Sim3 but with a steeper left arm plane).


The question is do golfers actually use any active forearm supination for release of PA3# to increase clubhead speed, especially when there is a moderate PA3 angle? I understand that you think PA3# is a club squaring power accumulator but his experiment proved that it could be a source of clubhead speed.

DG

The way you interpret Sasho's study results is very different to the way I would interpret his results. His results show that if one only relies on his passive torque technique to get a square clubface by impact, then clubhead speed will be reduced by 22%. That means that it is reduced by 22% relative to the normal PA#3 release situation when a golfer uses an active PA#3 release action. However, that does not mean that the normal PA#3 release action situation (using an active PA#3 release action) creates more clubhead speed compared to a scenario where a golfer uses a very strong lead hand grip strength (like Jamie Sadlowski) and does not have to use an active PA#3 release action.

Here are two series of capture images.

Jamie Sadlowski's downswing

Note that the back of his lead hand does not rotate between P6 => P7 so he is using very little (if any) active left forearm supination between P6 => P7.

Ernie Els downswing

Note that the back of his lead hand rotates ~90 degrees between P6 => P7 due to an active PA#3 release action.

However, that active PA#3 release action should not increase his clubhead speed if his lead arm speed and MoF values between P6 => P7 are exactly the same as Jamie Sadlowski's (meaning that the PA#2 release speeds are identical). Why should it?

In order words, the 22% decrease was due to a comparison between a PA#4 release => PA#2 release => PA#3 release (passive) versus a PA#4 release => PA#2 release => PA#3 release (active). However, that does not mean that a PA#4 release => PA#2 release => PA#3 release (active) will produce more clubhead speed than a PA#4 => PA#2 release.

Jeff.

[imperfectgolfer]

DG,

You wrote-: "In his own research article he conducted a Sim 3 experiment with the clubshaft travelling on the same plane as the lead arm but then actively switching on a 'lead forearm supinatory torque generator' about 0.16s into the downswing. This resulted in a square clubface at impact but 22% increase in clubhead speed compared to his passive torque experiment (Sim 1 where the clubshaft plane was set under the lead arm plane with forearm generator switched off)."

Who does SIM 1 apply to when the clubshaft is traveling on the same plane as the lead arm between P4 => P7?

Surely, it would be Phil Mickelson, who does not shallow his clubshaft between P4 => P6. Then, PM uses an active PA#3 release action very late in his downswing between P6.7 => P7 when his MOI is very small. If the MOI is small and if one uses an active PA#3 release action, then the PA#3 release phenomenon is not going to slow down the club that was efficiently released by PA#2 and clubhead speed at impact should be high.

Who does Sim 3 apply to when the clubshaft is set well below the lead arm plane between P4 => P6?

It would be Sergio Garcia - as seen in the following image.

From that P5.5 position, SH is going to start to release PA#2 . However, he also has to release PA#3 at the same time because he needs to start his left forearm supination action earlier so that the release of PA#3 overlaps with the release of PA#2 - because he is going to come into impact with a large accumulator #3 angle. If he did not use an active left forearm supinatory action then it would slow down his release of PA#2 because his MOI is very high in the rotary plane of lead forearm supination. So, of course, it would be expected that he would lose 22% of his clubhead speed if he only relied on a passive PA#3 release phenomenon.

Conclusion - a golfer who comes into impact with a large accumulator #3 angle, like SG, cannot rely on a passive release of PA#3 and he needs a very active PA#3 release phenomenon.

Finally, note that the comparison between Sim 1 and Sim 3 does not address the issue as to whether the PA release sequence of PA#4 release => PA#2 release => active PA#3 release (using a neutral lead hand grip strength) will result in a faster clubhead speed than the PA release sequence of PA#4 release => PA #2 release (with a very strong lead hand grip strength).

Jeff.

[dubiousgolfer]

Dr Mann

SIM1 was where the shaft started 10 degrees under the lead arm plane (all torque generators switched on except forearm). This swing ended up with a PA3 angle at P7.
SIM3 was where the early downswing only started on the lead arm plane (all torque generators switched on). This swing ended up with a PA3 angle at P7

We also don't know what tweaks he did on the other torque generators to optimise clubhead speed and ensure clubface square by impact for SIM1 vs SIM3 , therefore there could be different PA#4 and PA#2 release aspects to cater for the passive and active PA#3 releases.

I think your 'Conclusion' above makes logical sense.

DG

[imperfectgolfer]

DG,

I unintentionally mixed-up Sim 1 and Sim 3 in my last post.

Jeff.

[dubiousgolfer]

Dr Mann

I'm still having the problem conceptualising the below:

"Note that his trail wrist is markedly bent back (extended) at his P6.2 position (image 1) and that it is far less bent back at his P7 position (image 4), which means that he is straightening his right wrist during his PA#3 release action. While he is moving his trail wrist in a straightening (palmar flexing) direction, he is also moving his trail wrist in a radial direction and the combination of those two wrist movements produces a circumductory roll motion of his trail wrist, which allows him to continuously keep his trail palm facing his lead palm during his PA#3 release action (while his trail forearm simultaneously becomes less supinated)."

There is negative torque in the hands approaching impact and the club is actually pulling on the hands (ie. the hands end up dragging the grip before P7). So are you saying that the circumductory roll motion of the right hand must be a combination of the club causing the straightening of the wrist , while the golfer is also actively radially deviating?

I cannot replicate that motion and still have the right palm facing the left palm while also keeping the right forearm supinated.

Is there a way you can perform these wrist motions on a video to demonstrate this biomechanical wrist action?

DG

[imperfectgolfer]

DG,

Look at topic 8b and watch the video of Maria Fassi - she does the same as Dustin Johnson.

Here are capture images viewed from DTL

Note how the right palm moves from P6 => P7. There has to be a counterclockwise roll motion of the right palm happening - and part of that roll motion is due a right wrist circumductory roll motion as her right wrist partially straightens and part of it is due to a decrease in the degree of right forearm supination.

Note that her right elbow continues to slide targetwards between P6 => P7. If her right elbow stalled at its position in front of her right hip area, the right elbow would straighten more and she would have more right forearm pronation happening between P6 => P7. By preventing a "running-out-of-right arm" scenario, she can keep her right forearm partially supinated into impact.

See topic 8c - note that Phil Mickelson pronates his trail forearm into impact because he "runs-out-of-right arm".

Jeff. 

[dubiousgolfer]

Dr Mann

I'm just going to post some slow motion images of Adam Scott, Rory, Tiger and Rickie Fowler's hands. I think I understand what you mean but what I see in these images is that the right wrist ulnar deviates as it loses its dorsiflexion approaching impact (while still retaining most of its supination as the left forearm supinates).  So that combination  of right wrist movement can be defined as the circumduction that you have mentioned in your article (although I understand that you define the lower half of the right palm moving towards the radial direction).

DG

Adam Scott




Rory




Tiger




Rickie

[imperfectgolfer]

DG,

You wrote-: "I think I understand what you mean but what I see in these images is that the right wrist ulnar deviates as it loses its dorsiflexion approaching impact (while still retaining most of its supination as the left forearm supinates). So that combination of right wrist movement can be defined as the circumduction that you have mentioned in your article (although I understand that you define the lower half of the right palm moving towards the radial direction)."

I agree with what you have written. As the right wrist straightens between P6 => P7, the ulnar half of the right wrist also rolls a lot so that the nails of the right 3rd/4th fingers can still face skywards at P7.

Your Rory photos are very instructive because you can see that the right forearm is becoming less supinated between P6 => P6.5 => P7 - by looking at the lower right radial bone relative to the right antecubital fossa.

Jeff.

[imperfectgolfer]

DG,

I have modified my downswing chapter as follows-:

"Note that his trail wrist is markedly bent back (extended) at his P6.2 position (image 1) and that it is far less bent back at his P7 position (image 4), which means that he is straightening his right wrist during his PA#3 release action. While he is moving his trail wrist in a straightening (palmar flexing) direction, he is also moving his trail wrist in an ulnar direction and the combination of those two wrist movements produces a circumductory roll motion of his trail wrist, which allows him to continuously keep his trail palm facing his lead palm during his PA#3 release action (while his trail forearm simultaneously becomes less supinated)."

I changed the bold-highlighted words to ulnar (instead of radial).

Consider these Dustin Johnson's capture images.

Note that two phenomena are happening to the clubshaft between image 1 => image 3 - the clubshaft is releasing (representing the release of PA#2), but when it releases it does not tumble over-the-plane, and it angles downwards.

Note that his right wrist is very extended and radially deviated in image 1. Then, it moves towards ulnar deviation as the right wrist straightens between image 1 => image 3.  The combination of ulnar deviation + right wrist straightening allows the right wrist to undergo a circumductory roll motion that allows the right palm to face more skywards while the right wrist straightens (which means that the back of the right hand moves more under the club handle). That right wrist motion of straightening combined with ulnar deviation torques the right forearm in a supinatory direction, and allows the right forearm to continue to supinate to a very small degree while the left forearm is supinating (accounting for the phenomenon of dual forearm supination) and the left wrist is uncocking.

Here is Jon Sinclair's graph.

Note that the green graph (lead forearm) starts to move towards supination at the start of that yellow zone.

In the first half of that yellow zone until the vertical white line (probably between P5.5 => P6.2) the trail forearm (red graph) is still supinating to a very small degree. Then the trail forearm starts to rotate in a pronatory direction between the vertical white line and impact.

So, between P5.5 and P6.2+, both forearms are supinating.

If the right forearm pronated earlier between image 1 => image 3 in the DJ's images and if the right wrist remained radially deviated while it straightens, it would cause the clubshaft to tumble over-the-plane to a small degree and the right palm would get more on top of the club handle. 

Jeff.