Optimising Clubhead Speed - Is this the real way?

[Goober]

Be nice if they had an app or training aid for the general public that would track body speeds. A way of seeing where fast or slow body rotation would help golfer A or B. And even sensors that would be placed on the body that would vibrate or make a noise when in a good or bad position. 
 

Also wonder what the correlation of hand speed, grip speed; shaft speed, and clubhead speed has. If they had a way of tracking those each individually as well 

[Wildthing]

Just a note to show how the trail wrist rolls (ie. it's called circumduction) during the late downswing from P6.5 -P7 . 

Most golfers trail wrist moves into less extension (ie. in the flexion direction or less cupped) while it also moves from radial to ulnar deviation (this is a coupled wrist movement happening together). The movement allows for the greatest range of motion for the wrist joint with least degree of stiffness.

If you check out this publication below you will see Fig 2d and 2e  that shows how the right hand rolls. If you look specifically at Fig 2d , you will see that moving from radial to ulnar deviation coupled with flexion causes the wrist joint to rotate/roll in the clockwise direction .  

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5555257/

Fig. 2
In-plane and out-of-plane kinematics for planar motions – (a) flexion-extension and (b) radioulnar deviation – and trajectories of complex motions – (c) dart thrower’s motion (d) clockwise circumduction and (e) anticlockwise circumduction – in hybrid control (solid lines) and cascade control (dotted lines), as compared to the desired kinematics and trajectories (dashed lines), with the hand in the vertically upward orientation, for a representative cycle of one of the specimens (X-axis represents radioulnar deviation, Y-axis represents flexion-extension).

-------------------------------------------------

So what relevance does all this have in the golf swing from P6.5-P7 ?

Golf 3d data graphs show the trail forearm is supinating for most of the downswing  until just before impact where it loses a bit of supination (very little) .  While all this is happening , the trail wrist is also rolling clockwise (ie. circumduction as described above) which will tend to rotate the grip of the club also clockwise  'OPENING ' the clubface. 

So it's a fallacy to assume that the trail forearm and wrist are trying to assist in closing the clubface in the late downswing from P6.5- P7 . 

But the above doesn't make sense because we know the lead forearm is supinating to close the clubface , so how can the trail forearm/wrist be doing the opposite while still allowing the clubface to square by impact (ie. for golfers who use a weak->neutral lead hand grip)?

There must be some other biomechanics in play that moves the whole trail arm/wrist unit around in 3D space to assist the lead forearm to close the clubface whilst also nullifying the 'opening' effect on the clubface caused by supination of the trail forearm and its wrist circumduction (in the clockwise direction).  I'm guessing it can only be body rotation, or/and internal rotation of the trail upper arm,  or/and trail scapula movement. 

Here's another publication 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3016043/#bib4

It shows that the wrist joint 'Range of Motion' to be the greatest with least stiffness for circumduction in the ulnar/flexion coupled movement. So it sort of makes sense that the trail wrist motion in the late downswing follows a path of least resistance.

 

Edited September 1 by Wildthing

[Wildthing]

Here is a tour pros lead/trail wrist graphs.

This tour pro has a neutral lead hand grip and he supinates it  (blue graph) from approx -26 degrees  to  +48 degrees  = total 74 degrees (at impact).

Now check out his trail wrist graphs . 

The green graph shows it moving from approx extension -70 degrees to less extension at -38 degrees (at impact) = total 32 degrees movement in the flexion direction.

The red graph shows it moving  from approx  -11  degrees radial deviation  to 19 degrees ulnar deviation (at impact) = 29 degrees movement in the ulnar deviation direction.

The blue graph shows that the wrist/forearm is supinating from -7 to +35 degrees = total 42 degrees 

His trail wrist is therefore rolling clockwise (circumduction) because of the coupled movements above and that will tend to open the clubface. 

The very small degree of pronation of the trail wrist/forearm just before impact is minimal.

So to summarise:

1. Lead forearm supinating 74 degrees closing the clubface by impact

2. Trail forearm supinating 42 degrees opening the clubface by impact. Note that if the trail forearm and clubshaft are at 90 degree angle to each other , then supination or pronation of the forearm will not rotate the clubface axially open or closed. 

3. Trail wrist circumduction opening the clubface by some unknown amount.

So the the whole trail forearm must be moved and reorientated in 3D space to offset any clubface opening effects caused by points 2 and 3 above and also allow the lead forearm to supinate 74 degrees .

 

Edited September 8 by Wildthing

[Andrew75]

Which tour pro?  Jim Thorpe? Adam Scott? Russell Henley? Ed Fiori?

 

[Wildthing]

28 minutes ago, Andrew75 said:

Which tour pro?  Jim Thorpe? Adam Scott? Russell Henley? Ed Fiori?

 

Gary Woodland - it has his name abbreviated on the top of the graphs 'G Wood'

Here are some more graphs:

 

[Wildthing]

Was looking at Charles Howard III golf swing in slow-mo and comparing it to his graph but noticed he seems to be releasing his fingers off the club post impact and maybe just before too.

https://www.youtube.com/watch?v=m8E79w4HM8k&t=3s

 

Look at the face-on view , his last 3 fingers seem to be the left side of the grip from our viewpoint.

 

[Wildthing]

Here are some graphs for Trail shoulder internal/external rotation . So it seems that from P5 , while the golfer is supinating his trail forearm and also face opening (I'm guessing not opening the clubface by any significant amount) by trail wrist circumduction, he is internally rotating his trail upper arm by about 35-40 degrees.  

So we have the clubface squaring mainly by lead forearm supination , supported by lower body and chest rotation, internal rotation of the trail upper arm , plus any adhoc left and right scapula movements.  To conduct research  on all these movements and discover cause and effect on the dynamics of the club is going to be a very complex and difficult task.

 

 

Here are some nice graphs showing axial rotational velocity of the club by a tour pro vs amateur. Note the plateauing off just before impact.

 

Here are the graphs again showing the axial velocity of the shaft for a pro vs amateur. Again one can see that the axial velocity dips just before impact (why?).

 

 

 

 

 

 

 

 

Edited September 5 by Wildthing

[Wildthing]

Here's another puzzle . 

Dr Sasho MacKenzie created a 'forward dynamics model' of a golfer and wanted to research if the model could perform a golf swing at speed while also squaring the clubface by impact without any muscular lead forearm rotation. 

The model's whole arm (it had no lead forearm segment and no trail arm) was designed so that it could rotate about its longitudinal axis.  The model's wrist was only allowed to radial and ulnar deviate with no flexion or extension.

So he setup the model to have the COM of the club to be under the arm plane for a distance of 7.3 cm . 

Then he  inclined the model torso to rotate about some constant angle to the vertical.

Then he inclined the model's shoulder to rotate about some constant angle to the vertical.  This constrained the  model's lead arm to to swing on one plane steeper than the torso rotational plane.

Then he tweaked the torque rotational generators of all the segments to rotate and maximise clubhead speed while ensuring the clubface was square at impact  (without any use of the models forearm rotational torque generator).

The model's swing above was titled SIM 1  (ie. Simulated Swing 1).

Here are the graphs showing the angular momentum of the lead arm/hand/club  during the downswing.

Looking specifically at the angular momentum graph, I estimated the passive torque the swing generated about the longitudinal axis of the models arm without any 'muscular' torque generation.

Torque = 'rate of change of angular momentum'  , so all you need to do is estimate the slope of the graph like I did below.

 

As you can see the 'passive torque' generated to rotate the models arm was 13.9 Nm so lets just opt for 14 Nm approx. 

But because the model's whole arm was being rotated , I can imagine the torque to rotate a forearm would be much less , maybe 60% . So lets guess that if the model had only a rotating forearm , the torque would be 14Nm x 60% = 8.4 Nm.

This 8.4 Nm is within the limitations of maximum male forearm muscular rotation which has been researched and found to be 11.9 +/- 3.7 N.m (see research abstract article below).

The peak clubhead speed was 36 m/s.

http://pubmed.ncbi.nlm.nih.gov/16713846/#:~:text=The peak torque values averaged

Now Sasho Mackenzie also used the model to create another 'Simulated Swing' titled SIM3.

This time the COM of the club was approximately  the same as the lead arm plane  (so very little passive torque created) but then he used the model's 'ARM' generator to rotate the club about its longitudinal axis  and optimised all the models torque generators (ie.torso , shoulder, arm, wrist)  to maximise clubhead speed while still squaring the clubface by impact.

The actual arm torque generator was activated at about 0.16 secs into the downswing which means the club was somewhere between P5- P5.5.  

The peak clubhead speed was 44 m/s , a whopping 8 m/s or approximately 18mph more than the passive torque only SIM1 swing.

Here again are the graphs for SIM3.

Again, I worked out the maximum slope of the angular momentum as being approximately 22Nm and that is above the the ability of a human forearm to rotate.  

Again the model is using a torque to rotate the whole arm at shoulder joint location and not the forearm. So let's assume if the model had a forearm segment the torque required would be 60%  = 22 x 60% = 13 Nm approx which is within the ability of a human forearm muscular capability. But can a human golfer generate that type of torque in the 40 msec time to close the clubface 70 degrees from P6-P7?

So can we assume that a real golfer could replicate what the model has done for SIM1 and SIM3? 

If you have weak forearms , maybe you can use the passive torque effect of SIM1 to square the clubface , but your clubhead speed would be less than if you had actively used your forearm as in SIM3.   To use the passive torque effect , your club would have to be on a shallower plane than your arm plane (or your arm plane steeper than your club plane). Maybe you can have a mix where you use the passive torque and then add some more with muscular active forearm torque.  Depending on your intent, you need to be able to create enough passive/active torque about the lead forearm axis (ie. in terms of clubhead speed and clubface alignment at impact).

The problem with the model vs real human golfer is as follows (and there could be more that I haven't thought about)  :

1 - The model doesn't have a forearm segment but rotates the whole lead arm using a torque generator located at the level of its shoulder joint.
2.- SMK had only one high speed camera and he mentions in his research article the following:

"Access to a single high-speed camera limited the model’s validation to two dimensions. This meant that the longitudinal rotation of the model’s lead arm could not be
quantitatively compared to that of the live golfer."

3. He did not quantify how much passive clubface squaring torque was generated in his models optimised swing for clubhead speed (which btw was 7 m/s less than a typical professional golfer). Therefore there is no way of knowing what effect it had on the model arm rotational torque generator.

Further , his research article shows a max 'Arm' torque of 25 Nm whereas the maximum human male forearm torque is 11.9 +/- 3.7 N.m (see research abstract article below).

pubmed.ncbi.nlm.nih.gov/16713846/#:~:text=The%20peak%20torque%20values%20averaged

Again, we cannot use his model ARM torque to compare the actual forearm torque generated by a human golfer.

4. There is no model trail arm.

5. Because the model has no legs there are no lower body torques taken into account.

 

Just so one can see the top of the backswing for SIM1 and SIM2, I've enlarged the images and I think the biomechanical reasoning why the clubhead would be above or below the lead arm plane at P4 must be the degree of lead arm pronation.

 

 

 

 

 

Edited September 8 by Wildthing

[Wildthing]

Is Rory using the passive torque effect.  Is the the clubshaft moving to a steeper swing plane relative to his hand path swing plane?

[Wildthing]

This is the correct way to view and measure body segment instantaneous plane of movements . If one is using a camera it would theoretically have to continuously move and track the body frame images from one position to another as the body segment plane changes from one instant to another (it would have to view in a direction along the swing plane).  Obviously , this is practically impossible so you have multiple cameras , optical or inertial sensors to compute plane angles , movements , velocities , etc. 

Here is an example where a DTL view is flawed to estimate arm swing plane angle and I have drawn some 'eyes' to approximate where you should be viewing it.

Here are blown up images of Rory's shaft plane steepening from the camera angle I chose (probably another flawed camera viewpoint).

Look at the yellow arrows to prove my point and you can clearly see that the shaft is steepening relative to the green wooded areas in the far background. But it's probably the wrong camera angle just like a DTL view, therefore I cannot be certain whether his shaft is steepening or shallowing. Even if we had 3D graphs showing his lead forearm supinating/pronating , one cannot assume that those actions alone are causing some net  'steepening/shallowing' of the club because there are other body movements that might change the orientation of the club shaft in space (need to look at the whole golfer body system).

So one can't really be certain what's happening in the golf swing by looking a 2D frame images and you need high tech 3D to conduct proper data measurements.

The camera angle is not ideal and in reality Rory might not be steepening the golf club , but it shows that looking at 2D images from the wrong viewpoint can be misleading.

Clubshaft Plane vs Lead Arm Plane During The Downswing

Here is a graph comparing the clubshaft plane to the lead arm plane during the downswing for a small number of golfers. It was from a research paper by Coleman & Rankin 2005 and titled "'A three-dimensional examination of the planar nature of the golf swing'.

They used a small but diverse number of golfers where only 2 of them were 'scratch' professional golfers.

Fig 7 is from their research article and you can see that P1 scratch golfer club graph (I've traced a red line to help see the graph)  was above the left arm plane 20 cm at P4 , steepened to 30cm in the early downswing and then progressively shallowed the club to below the left arm plane by about 20 cm at P6 . Then it club started to move progressively in the 'above' left arm plane direction from P6 -P7.

Now look at P2 scratch golfer (yellow traced line) where his club was approximately 30 cm below the left arm swing plane and remained virtually constant for a while before shallowing to 40 cm below the left arm plane until he reached a position 0.155 secs before impact (between P5-P5.5?). Then his shaft progressively steepened all the way to P7 , going above the left arm plane at around 40 msecs before impact.

How can one tell whether there was a passive torque happening for P2 golfer or not ? In my opinion it is impossible to know if it was a passive torque or active forearm supination.

Now look at Jon Sinclairs graph for lead forearm supination/pronation graph for 60+ elite pro golfers .

One can see that from P5  (AP position - meaning ARM PARALLEL)  all coloured lines are moving in the supination direction. Does that mean the club shaft is steepening?  As I've said before, you need to look at the whole system in 3D and not a body segment in isolation before assuming what is happening.

The blue graph seems to be labelled 'Normal ' while the red and yellow seem to be 'Outliers' (unsure because the graphs are very blurry).

Here is an interesting graph from Dr Kwon which I will use in a later post .

 

 

Edited September 16 by Wildthing

[Wildthing]

I was puzzled whether golf pros were using Dr Sasho Mackenzie's passive clubface squaring torque and thought the only way to find out is to search for any EMG research and I found one>

Electromyographic analysis of forearm muscles in professional and amateur golfers

I can't find the whole research article but basically 10 pros and 10 amateurs had needles inserted in their forearm muscles which monitored their activity when they swung the golf club . The phases of the golf swing are below with the table of results .

Would you believe that the only main forearm muscle I was interested in (ie. the Supinator) was not included in their research.  

But here is the puzzle , why is the lead arm 'PRONATOR TERES ' muscle 88% of maximum in those 10 pro golfers? It almost seems that they are trying to stop  the clubface from closing in the acceleration phase of the swing 'C'  from P6-P7.

Is the passive torque so great that the golfer has to try and stop the clubface from closing too quickly?  But hold on, the 'PRONATOR TERES' is also involved in flexing the elbow like a bicep curl and I've seen quite a few pro golfers with bent elbows going into impact.

Another puzzle to sort out in the golf swing - nothing ever seems straightforward.

 

Results: Compared with professional golfers, amateur golfers had more muscle activity in the pronator teres of the trail arm (right arm in a right-handed golfer) in the forward swing phase (120.9% maximum manual muscle test vs 57.4% maximum manual muscle test; P = .04) and a trend toward increased activity in the acceleration phase (104.8% maximum manual muscle test vs 53.1% maximum manual muscle test; P = .08). In contrast, professional golfers had more muscle activity in the pronator teres of the lead arm (left arm in a right-handed golfer) in the acceleration phase (88.1% maximum manual muscle test vs 36.3% maximum manual muscle test; P = .03) and a trend toward increased activity in the early follow-through phase (58.1% maximum manual muscle test vs 28.8% maximum manual muscle test; P = .06).

Conclusion: Pronator teres muscle activity in the golf swing differs significantly between professional and amateur golfers.

Here is a another summary

 

Edited September 8 by Wildthing

[Shankster]

Still mind blowing, 5 years later.  I need to make an appointment with the Doc about this passive clubface squaring thing.

[Goober]

I think I’m understanding this now.After reading this well thought out thread by Wildthing.Reminds me of the Manuel Torre string drill.Or even the gem training aid.The body and club are as one.A nice feeling to have

Edited September 9 by Goober

[Wildthing]

I've been trying to find out whether there are any 3D systems (like AMM3D and GEARS) that measure lead arm and clubshaft instantaneous planes during the downswing , but surprisingly , they don't . So I looked through all the research docs that I have and found this one by Dr Kwon.

"'Assessment of planarity of the golf swing based on the functional swing plane of the clubhead and motion planes of the body points'

Here is the  'Driver'  swing graph which shows the various body point plane measurements for 14 golfers , for which 12 were scratch or better golfers and the other two 3 hcp.

 

 

It seems as if the clubhead swing plane is starting off flatter  slightly steeper than the lead hand plane in the downswing , where both are getting progressively steeper. But the clubhead plane rate of steepening is greater than the lead hand plane (while still being below above the lead hand plane) until they reach position to just after club vertical. The latter suggests an OTT type movement of the club from top of backswing to just after club vertical in the downswing (that seems weird to me and maybe I am misinterpreting the graph) . The clubhead then moves flatter (ie. shallows) relative to the lead arm plane from just after club vertical to club horizontal and then stays constant on the FSP (functional swing plane)  into ball impact position (BI).  The graph is showing the clubhead is now below the lead hand plane from just after club vertical as the lead hand continues to slightly steepen until ball impact. So just before impact the clubhead is still on the FSP but the lead hand is now below the FSP.

This may indicate that there may be some Dr Sasho MacKenzie passive club squaring torque happening between 'just after club vertical' to 'horizontal' which is causing the lead forearm to supinate during the downswing . The other alternative is the golfer is actively using muscular lead forearm supination to steepen the clubhead plane at a greater rate than the degree of lead hand plane steepening.

ADDENDUM 

I think my interpretation of that graph is all wrong but I will await a reply from Dr Kwon.

On reflection, I think that graph is showing the shaded areas in the frame image below but versus time. 

When I look at the images below it looks like both the hand path and clubhead are shallowing relative to the FSP. 

 

But now I'm confused because another research study by Coleman & Rankin produced this graph showing that the left arm is steepening during the downswing.

 

 

 

Edited Thursday at 11:25 PM by Wildthing

[Wildthing]

I think Dr Kwon's you-tube videos are quite fascinating and seems to infer that although the body pivot is an important transverse plane torque contributor  (ie. vertical green arrow vector) to the golf downswing in terms of overall clubhead speed, it is the more frontal plane torque generating abilities of the golfer that is generally larger (ie . the red horizontal arrow vector).  The movement of the arms more up and down seems to be the main contributor of the resultant torque normal to the FSP (functional swing plane) which is the black arrow in the image below. 

https://www.youtube.com/watch?v=pj5pbW0yE8g

 

Edited September 30 by Wildthing

[Josh Parker]

Some interesting data and I'm going to have to start from the beginning. 

[Wildthing]

I've always wondered how pelvic rotary motion can influence lead arm movement and one can easily see this from the video and images below.

The 'Latissimus Dorsi'  is connected to the iliac crest (on the pelvis) and also to the humerus (upper arm).  

https://www.youtube.com/watch?v=m78cUG7f_tE

 

So when the pelvis rotates on a flatter plane in the downswing , one can use an isometric muscle contraction , that would pull down the humerus in a more vertical plane direction.

 

On another note, I've been trying to find a simplified analogy to show how the lead arm might move in the golf swing if the lower/upper body pivot was driving the downswing. All I could imagine are these images of a carousel swing. The left 2 images is where the arm (I've drawn it as a yellow line on one of the ropes) is below the rotating roof which one can regard as the 'shoulder' . Now , just forget about gravity for the moment, you can see that when the 'roof/shoulder' rotates , while the arm is below the shoulder plane , it will tend to move upwards. Now if I turn carousel upside down so that the arm is above the shoulder plane , a rotation of the shoulder will cause the arm to move downwards.

So the shoulder rotation , even on a flatter plane will bring the arm down if it started the downswing from a position above the shoulder plane but I doubt it's going to be a very forceful movement . I certainly have my doubts it will be a major contributor to creating linear forces along the hand path in the early downswing but I'd have to do the maths to confirm (which I'm not too good at).

Edited October 4 by Wildthing

[Wildthing]

Interesting looking at Gary Woodland's Swing Catalysts graphs where he has low vertical GRF but can boom his driver. 

Apparently (in the early downswing) he can generate a lot of angular momentum in the 'frontal plane'  by 'unweighting' himself  while applying mainly horizontal grf with his trail leg and minimising his vertical grf . Unweighting meaning that his net vertical GRF is below his body weight which is the 100% horizontal line in the bottom graph.

The net GRF force vector will create a large moment arm about his COM ( see Dr Kwon screen images below) and that generates a large Torque in the frontal plane.  Remember that in physics ,  Torque = Rate Of Change Of Angular Momentum.

So, in the early downswing a 'large horizontal GRF' + 'smaller vertical GRF'  will create a large 'Moment Arm'  (ie. a larger torque about COM and greater rate of change of angular momentum).

Edited Friday at 05:26 PM by Wildthing

[Wildthing]

Following on from my previous post here are some Swing Catalyst graphs showing a significant degree of 'unweighting' where both golfers , Charles Howell III  and Jose Ballester create lots of clubhead lag.  The moment arm that they generate about their COM (via net GRF force) can be increased by both:

1. Unweighting as per Dr Kwon's screen images I previously posted .

2. Rightwards leaning posture that Gary Woodland, Charles Howell III and Jose Ballester all seem to use. 

 

In the above force plate graphs for Jose (the bottom one) , there is significant unweighting but it doesn't continue to become more unweighted during the early downswing .  His vertical grf is only 158% which is less than typical 200% measured. His horizontal grf is large (top graph) , while his frontal torque 35%  is greater than his transverse torque 22%.

So we have a situation where all 3 golfers have:

1. Rightwards leaning of upper body.

2. Created clubhead lag (how?).

3. Generated a net grf force with a large horizontal component and small vertical component to maximise the moment arm (how?).

My question 'how' means what internal movements is the golfer making to create clubhead lag and those GRF patterns?

--------------------------------

On a separate manner , I am still trying to identify whether lateral motion of the golfers lead shoulder during the early downswing, can create enough 'frontal plane torque' on the arms/club unit to significantly increase clubhead speed especially between P4 (top of backswing) to P5 lead arm horizontal (look at diagram below).  My gut feeling is that it can't but I don't have enough data to confirm that opinion. If I had the data , then maybe I could confirm whether the lower/upper body lateral shift can create significant speed of the 'arms/hands/club' on a steeper plane relative to the flatter pelvis/shoulder plane.

 

Edited Monday at 02:18 PM by Wildthing

[Wildthing]

I think I may have found a possible answer for how the lead arm/club unit can be brought down on a steeper plane by lower body action .

The explanation I found is on page 84 of Cochran & Stobbs book 'Search For The Perfect Swing'. It shows images of how the pelvic motion (which looks like a partial rocking motion in the frontal plane about the horizontal axis) can bring down the 'upper torso/arms/club' unit on a more steeper frontal plane but only if there is no "slack higher up" (which I assume is some muscle stretch of the abs/lead shoulder girdle).

They state " The combination of this rotation with rotation about the vertical axis produced by the unwinding of the hips turns the massive hub around an inclined axis; this is the ideal movement with which to set the downswing going".

Doesn't Dr Kwon recommend this type of rocking of the pelvis with his shift/turn lower body action? Is this what he means by a body driven golf swing?

The pelvis lateral motion they described above would seem to require more horizontal grf. Also, the images show a more rightwards leaning posture during the early downswing.

Also , page 81 , they claim the legs and hips are the "engine" of the golf swing by calculating how much power is required to create the clubhead speed by impact. The muscles that move the arms are not the main contributor of power in the golf swing according to their calculations.

Addendum

On reflection , I think the authors just used that 'theory' above (as there isn't any evidence to support it)  to fit in with their double pendulum model of the golf swing.  Golfers don't usually reorientate their spine as shown above and it looks like a 'reverse tilt/pivot'  that can put a lot of stress on your lumbar spine.

So I still haven't found any evidence (from a kinematics/kinetic perspective) to support any body driven swing which can also explain how it could bring the lead arm down on a significantly steeper plane than the pelvis and torso. Yet there are golf scientists who claim that shoulder girdle muscles alone would be unable to accelerate the clubhead to the speeds seen by tour pros.

Maybe the torque that moves the arms, especially the lead arm, on a steeper plane is simply just a component of the 'lower/upper'  body pivoting torque (ie. that is causing rotation on a flatter plane).

I've found a graph from Dr Sasho Mackenzies forward dynamics model (ie. 3D)  for the lead arm swing plane .

It shows that the lead arm plane starts flattening from top of backswing to about lead arm horizontal and then steepens to impact. I cannot see an explanation as to why ,but I'm suspecting that the torso had more of an influence on the lead arm swing plane in the early downswing than the shoulder torque (being applied on steeper plane).

So can it be assumed that the lead arm downswing was being partially driven by the torso and that constitutes a 'body driven' swing?

Is this same lead arm swing plane pattern normally seen for tour pro golfers on AMM3D and GEARS?  I'll have to investigate further.

One has to take note that this forward dynamics model didn't have a lower body . So if there is some sort of connection via oblique muscles connecting pelvic rotation to torso, then in a real life golfer, the torso could also be theoretically driven by the lower body in the early downswing (aka Ben Hogan style).

Edited 9 hours ago by Wildthing