Analysing the controversial AMG video

[dubiousgolfer]

I looked at that SMK video 'Linear and Angular Work during Downswing of a PGA Tour Major Winner' and was interested to see how clubhead speed varied with these forces over time, so created a graph from the readings.

Here is the graph if anyone is interested:

The x axis is time but you have to read the graph right to left from approximately club vertical (0.083 secs) to P7 (0.000 secs).

The y-axis for CHS is the blue graph in mph , while the Linear Hand Force (I've abbreviated it to Force) is the red graph measured in Newtons.



The actual clubhead speed seems to increase almost linearly over time while I assume the big increases in force must be more involved in changing the club's direction.

Gave me a better idea of how clubhead speed varies over time compared to the clubhead angular velocity graphs (seen in kinematic sequence graphs).

DG

[imperfectgolfer]

DG,

You wrote-: "The reason for the increased force from P5.5-6.2 is because the COM of the club is moving away from target at P5.5 , therefore DJ is having to apply extra force on the grip to both change the COM direction targetward plus add some clubhead speed."

That makes sense!

We know that PA#2 starts to release between P5.5 => P6.2 and that the initial direction of clubhead motion is away from the target,and away from the hand arc path, which means that extra "force" is need at the level of the lead hand grip on the club handle to counteract that phenomenon while making sure that the lead hand continues on its path along the hand arc path in a targetwards direction.

Jeff.

[dubiousgolfer]

Dr Mann

I am confused about this JS graph



If the trail forearm is supinating from P4-P6, why isn't the lead forearm pronating more? It seems to be moving to less pronation.

Is this a graph of an individual tour pro golfer or some average across many?

DG

PS. I'm assuming this video shows how he is interpreting the kinematics of the wrists from the above graph data but how can club shaft shallowing happen if both the trail and lead forearm are supinating at the same time? Is this why they have assumed a reverse motorcycle move needs to happen?



 

[imperfectgolfer]

Mar 10, 2023 18:57:07 GMT -5 dubiousgolfer said:

Dr Mann

I am confused about this JS graph



If the trail forearm is supinating from P4-P6, why isn't the lead forearm pronating more? It seems to be moving to less pronation.

Is this a graph of an individual tour pro golfer or some average across many?

DG

PS. I'm assuming this video shows how he is interpreting the kinematics of the wrists from the above graph data but how can club shaft shallowing happen if both the trail and lead forearm are supinating at the same time? Is this why they have assumed a reverse motorcycle move needs to happen?



 

Here is my tentative explanation as to why the lead forearm may not be pronating much during the clubshaft shallowing action between P4 => P6.

Consider Henrik Stenson's downswing - using the intact LFFW technique.

Image 3 is at P4 and image 4 is at P5+.

He is shallowing the clubshaft between image 3 and image 4 by performing an active right upper arm adduction maneuver using a pitch elbow motion with a small degree of right forearm supination. The back of his GFLW must be slightly more horizontal to the ground in image 4 than image 3 and if it is not happening due to left forearm pronation then it is presumably happening due to a small increase in the degree of internal rotation of the left humerus.

There is more clubshaft shallowing happening between image 4 and image 5 and one can see that his right forearm is supinating more as his right elbow straightens to a small degree. Note that his left wrist is becoming less cupped as the club starts to release due to less radial deviation of the left wrist, and that club releasing action seems to allow the clubshaft to continue to shallow without him having to pronate his lead forearm more between image 4 and image 5 - considering the fact that his hands are moving more towards the target as it continues to move down the hand arc path.

You also asked-: "how can clubshaft shallowing happen if both the trail and lead forearms are both supinating at the same time?"

Here is Gary Woodland's early-mid downswing action.

Note that GW is shallowing the clubshaft to a small degree between P4 (image 1) and P5.2 (image 3) and it looks like he is pronating his lead forearm slightly more.

Between P5.2 (image 3) => P6 (image 5) there is very little additional clubshaft shallowing happening while he is performing the dual forearm supination phenomenon, and I think that the fact that he is palmar flexing his lead wrist while he is simultaneously starting his early lead forearm supinatory phenomenon allows him to shallow the clubshaft to a small degree - because the lead wrist palmar flexion phenomenon angles the clubshaft slightly more groundwards.

Jeff. 

[dubiousgolfer]

Dr Mann

Yes, that seems like a very good explanation.

"if it is not happening due to left forearm pronation then it is presumably happening due to a small increase in the degree of internal rotation of the left humerus".

I don't think AMM3D measures internal/external rotation of the humerus to confirm your theory above but I have found some evidence of a pro golfer that doesn't conform to JS's graph. It's actually in this video conversation between Larry Rinker and JS below:



If you look at 6:19 7:58, JS is showing the 3D graph of the lead wrist/forearm of a tour-pro player who has the lowest ROC in his database who I think is Viktor Hovland, because I remember SMK saying that he had the lowest ROC of around 300 deg/s. Also, when you look at the AVATAR it looks very similar to VH's golf swing pattern.

From P4 to P4.8 , the blue graph' shows his left forearm pronating, not supinating (as implied in JS's graph in my previous post) while he is shallowing the club (see video below from 3:05- 3:06 and images 1,2 and 3 further below).






Maybe it would have been more informative if JS had produced a bottom and top range of graphs for lead forearm pronation/supination with a mean graph, as I think there could be many golfers who don't shallow the way JS describes in that video with Chris Como.


DG

[imperfectgolfer]

Mar 14, 2023 20:13:55 GMT -5 dubiousgolfer said:

Dr Mann

Yes, that seems like a very good explanation.

"if it is not happening due to left forearm pronation then it is presumably happening due to a small increase in the degree of internal rotation of the left humerus".

I don't think AMM3D measures internal/external rotation of the humerus to confirm your theory above but I have found some evidence of a pro golfer that doesn't conform to JS's graph. It's actually in this video conversation between Larry Rinker and JS below:



If you look at 6:19 7:58, JS is showing the 3D graph of the lead wrist/forearm of a tour-pro player who has the lowest ROC in his database who I think is Viktor Hovland, because I remember SMK saying that he had the lowest ROC of around 300 deg/s. Also, when you look at the AVATAR it looks very similar to VH's golf swing pattern.

From P4 to P4.8 , the blue graph' shows his left forearm pronating, not supinating (as implied in JS's graph in my previous post) while he is shallowing the club (see video below from 3:05- 3:06 and images 1,2 and 3 further below).






Maybe it would have been more informative if JS had produced a bottom and top range of graphs for lead forearm pronation/supination with a mean graph, as I think there could be many golfers who don't shallow the way JS describes in that video with Chris Como.


DG

Here is a Sinclair graph showing one standard deviation of the lead forearm rotation graph. It also includes a few examples of pro golfers - note that the blue golfer has increased left forearm pronation happening in his early downswing.

You also posted a graph of a golfer from the LR video that shows increased left forearm pronation happening between P4 => ~P5.5 and which you believe represents Viktor Hovland.

Here is his clubshaft shallowing phenomenon.

It certainly looks (from a visual perspective) that his lead forearm must be more pronated in image 5 compared to image 1.

Listening to that LR video between the 8:00 - 8:25 minute time points, JS claims that VH's left wrist  is 4 degrees extended at P7 and 24 degrees extended at P7.5.

Here are capture images of VH's DH-hand release action.

Image 1 is at P7 and image 5 is at P7.5.

Here are close-up views of his left wrist at P7 and P7.5.

It is hard for me to accept that his left wrist is 20 degrees more extended at P7.5 compared to P7.

Noting that the back of his left wrist is almost perpendicular to the camera angle at P7.5, I measured the difference in the angle between the red line and an imaginary line drawn from the end of that red line to the 2nd knuckle and that angular difference measured 15 degrees. If that represents his degree of lead wrist extension at P7.5 and it was 4 degrees extended at P7, then the difference is ~11 degrees. Then by extrapolation, I could imagine that his lead wrist is more extended by ~5 degrees at P7.2 compared to P7, which is a small enough amount to still allow a golfer to be regarded as being a DHer at P7.2.

Jeff.

[dubiousgolfer]

Dr Mann

The other point to note is that the VH avatar is not at P7.5 when JS stops the running of the swing. It's approximately at P7.7 when there is probably more lead wrist extension .




The above avatar position is closer to P7.5, maybe 7.4, and one can see that the vertical green line on the graph is within the plateau section of the blue and green lines.

DG

[imperfectgolfer]

Mar 15, 2023 10:32:17 GMT -5 dubiousgolfer said:

Dr Mann

The other point to note is that the VH avatar is not at P7.5 when JS stops the running of the swing. It's approximately at P7.7 when there is probably more lead wrist extension .




The above avatar position is closer to P7.5, maybe 7.4, and one can see that the vertical green line on the graph is within the plateau section of the blue and green lines.

DG

That's a good point seeing that the clubshaft is more bypassed the lead forearm (from an angular rotational perspective) at P7.7 compared to P7.5.

JS also makes a large mistake in that video by thinking that using the intact LFFW technique is equivalent to handle-dragging - see the 8:40 - 9:00 minute time point of the video. It is obvious that VH is extending his left wrist and supinating his lead forearm through impact in those DHer-capture images between image 1 and image 3, but the amount is not large enough to cause the clubshaft to bypass his lead forearm (from an angular rotational perspective) between P7 => P7.2 - and that allows VH to keep his clubface square to his clubhead path in the early followthrough.

Jeff.

[dubiousgolfer]

Dr Mann

I made a mistake in a previous post regarding Dr Sasho MacKenzie saying Victor Hovland's ROC being 300 deg/sec. See Ping twitter below.

With a closure rate of 2551.50 (degrees/sec), no player measured in ENSO has less rotation of the face through impact with a driver than Viktor Hovland.

DG