Bent Left Arm in Backswing - Pros and Cons

[dubiousgolfer]

Dr Mann

There are several golf instructors that promote the idea of a bent left arm in the backswing , while many others don't (ie. they prefer a comfortably straight left arm). They claim that a bent left arm can be a source of extra leverage in the early downswing to optimise clubhead speed while others (like Kuykendall claims it is body friendlier too). I've provided some examples of their videos and statements below and would be interested to hear (when you have any spare time) your critical opinion of their claims. There is the obvious issue that a bent left arm means a constantly changing radius in the downswing that adds another timing factor to the golf swing but does this outweigh any positive advantages of a bent left arm (ie. reduced strain in back and shoulders)?

For example, Mike Malaska and Bob Toski produced this video 





Lee Comeaux says  " It's OK for the left arm to bend at the top of the backswing."

Dave Tutelman says: ""I agree with this. It would increase the total club angle for people with flexibility problems, which could increase their distance. A bent left arm is only an issue late in the downswing. As long as it is extended later during inertial release, everything should be just fine."

Kuykendall says: Bend the Left Arm at the Elbow Through 90 degrees

• Virtual removal of back problems 

• Virtual removal of shoulder problems 

• Increases clubhead speed and 

• Increases accuracy 

When the left arm bends through 90+ degrees at the left elbow and only bends between 10 and 15 degrees between the left forearm and the shaft, the powerful left triceps are moving a lever the length of the left forearm and the shaft. This provides for the longest lever with the most force to move it.

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Here's another video that claims that a pro golfer has progressively more left arm bend in the backswing and downswing to impact , compared to the amateur golfer who bends more in the backswing and hyperextends in the early downswing to impact. So doesn't this almost promote more left arm bend in the backswing but to never try and hyperextend in the downswing (and keep the left arm comfortably straight , maybe even relaxed)?

[imperfectgolfer]

Apr 22, 2018 6:36:37 GMT -5 dubiousgolfer said:

Dr Mann

There are several golf instructors that promote the idea of a bent left arm in the backswing , while many others don't (ie. they prefer a comfortably straight left arm). They claim that a bent left arm can be a source of extra leverage in the early downswing to optimise clubhead speed while others (like Kuykendall claims it is body friendlier too). I've provided some examples of their videos and statements below and would be interested to hear (when you have any spare time) your critical opinion of their claims. There is the obvious issue that a bent left arm means a constantly changing radius in the downswing that adds another timing factor to the golf swing but does this outweigh any positive advantages of a bent left arm (ie. reduced strain in back and shoulders)?

For example, Mike Malaska and Bob Toski produced this video 





Lee Comeaux says  " It's OK for the left arm to bend at the top of the backswing."

Dave Tutelman says: ""I agree with this. It would increase the total club angle for people with flexibility problems, which could increase their distance. A bent left arm is only an issue late in the downswing. As long as it is extended later during inertial release, everything should be just fine."

Kuykendall says: Bend the Left Arm at the Elbow Through 90 degrees

• Virtual removal of back problems 

• Virtual removal of shoulder problems 

• Increases clubhead speed and 

• Increases accuracy 

When the left arm bends through 90+ degrees at the left elbow and only bends between 10 and 15 degrees between the left forearm and the shaft, the powerful left triceps are moving a lever the length of the left forearm and the shaft. This provides for the longest lever with the most force to move it.

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

Here's another video that claims that a pro golfer has progressively more left arm bend in the backswing and downswing to impact , compared to the amateur golfer who bends more in the backswing and hyperextends in the early downswing to impact. So doesn't this almost promote more left arm bend in the backswing but to never try and hyperextend in the downswing (and keep the left arm comfortably straight , maybe even relaxed)?

I reject Kuykendall's reasoning that bending the left elbow by 90 degrees in the backswing is advantageous. However, I have no problem when golf instructors talk of adopting a comfortably straight left arm, which is slightly bent (eg. Jordan Spieth's golf swing). I also think that having a very straight left arm (like Adam Scott and Lexi Thompson) is very acceptable if it can be achieved in a biomechanically comfortable manner. Some golfers find is very easy to have a very straight left arm without any muscular tension and that is very acceptable biomechanically, and I reject any rigid golf instructional "belief" that having a very straight left arm is incorrect.

I don't agree with Tutelman's argument that having a bent left arm at P4 could potentially increase driving distance. I think that when the left arm straightens passively in the downswing that it will not have any significant effect on the swing radius between P6 and impact or on the maximum achievable clubhead speed at impact.

In summary, I think that having a slightly bent left arm, or a very straight left arm, are equivalent if they can be achieved in a biomechanically comfortable manner.

Jeff.

[dubiousgolfer]

Many thanks for your reply . Yes , I cannot see any great advantage with a bent left arm other than maybe creating a greater swing path distance to give more time to accelerate the clubhead to a greater velocity until 'release and CF effect takes hold'.

One might be able to apply a greater Force at the hands/grip  (for a given shoulder Torque  using F= T/r, where r is the distance of the coupling point to the arm fulcrums or shoulder sockets) with a bent left arm in the early downswing, but then as you pivot your upper body , the radius of the hand arc is smaller. We then have the possibility of CF effect happening early , especially if you have passive left wrist allowing easy uncocking.

Then additionally , if one actively held off that early release (CF effect) by stiffening the wrists or applying an active negative torque in the early downswing , we have all sorts of extra timing issues with the straightening of the left arm to allow an optimal release that will maximise clubhead velocity and square clubface by impact.

[dubiousgolfer]

I'm revisiting this thread to show excerpts of an article that was written by a scientist (Moran Coxon- Senior Scientist Hughes Missile Systems) back in 2009. I couldn't understand any of the high level maths involved but if correct then there are some interesting theoretical conclusions he has arrived at.

The article can be found and the .pdf downloaded free from this website link (but it omits the spreadsheet that he produced for public distribution).

www.semanticscholar.org/paper/Was-Vardon-Right-Coxon/5dec5556dee1f1fb8f53b8f9b280d10df2626342

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In order to get a better feel for the situation let us compare two very possible cases (Fig. 4). In the first case the golfer uses a straight left arm, raises his hands to shoulder height (θ(0) = 90 deg) and uses a 90 deg wrist cock angle (β(0) = 90 deg). This configuration leads to a clubhead speed at impact of 31.88 m/s.






Now consider the same set up except that the elbow is now bent through 90 deg. (φ(0) = 90 deg). The clubhead speed at impact is now 44.48 m/s a whopping 39.5% increase! This translates into an increase in distance of approximately 57 m. While it is impossible to know exactly what Vardon did there can be no doubt that a bent left arm yields superior results My own preference (following Dr. Leonardi closely) is for a lower position of the hands corresponding to θ(0) = 75 deg. This results in a clubhead speed of about 91 mph but the position is extremely easy to achieve and places very little stress on the lower back – an important factor for those of us in our later years. As to the matter of improved accuracy I can only offer an opinion. It seems to me that this is probably due to the more upright nature of the swing resulting in a swing path that is more along the line of play.

Conclusion
The primary motivation for this work was to provide a theoretical justification for the superiority of the “Vardon Swing”, in particular as it is propounded in Reference [2]. I believe that aim has been satisfied. It remains a mystery as to why this approach to the golf swing has received so little attention from the golf profession. However, in the process a spreadsheet has been developed, which provides a useful tool for investigations of the golf swing, and which can be replicated by anyone with the necessary mathematical basics. All manner of “what if” exercises can be performed (changing the club, altering the total time of the swing, changing the allowable torques, examining the effect of gravity and so on).
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DG

[imperfectgolfer]

Apr 30, 2020 11:19:22 GMT -5 dubiousgolfer said:

I'm revisiting this thread to show excerpts of an article that was written by a scientist (Moran Coxon- Senior Scientist Hughes Missile Systems) back in 2009. I couldn't understand any of the high level maths involved but if correct then there are some interesting theoretical conclusions he has arrived at.

The article can be found and the .pdf downloaded free from this website link (but it omits the spreadsheet that he produced for public distribution).

www.semanticscholar.org/paper/Was-Vardon-Right-Coxon/5dec5556dee1f1fb8f53b8f9b280d10df2626342

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



In order to get a better feel for the situation let us compare two very possible cases (Fig. 4). In the first case the golfer uses a straight left arm, raises his hands to shoulder height (θ(0) = 90 deg) and uses a 90 deg wrist cock angle (β(0) = 90 deg). This configuration leads to a clubhead speed at impact of 31.88 m/s.






Now consider the same set up except that the elbow is now bent through 90 deg. (φ(0) = 90 deg). The clubhead speed at impact is now 44.48 m/s a whopping 39.5% increase! This translates into an increase in distance of approximately 57 m. While it is impossible to know exactly what Vardon did there can be no doubt that a bent left arm yields superior results My own preference (following Dr. Leonardi closely) is for a lower position of the hands corresponding to θ(0) = 75 deg. This results in a clubhead speed of about 91 mph but the position is extremely easy to achieve and places very little stress on the lower back – an important factor for those of us in our later years. As to the matter of improved accuracy I can only offer an opinion. It seems to me that this is probably due to the more upright nature of the swing resulting in a swing path that is more along the line of play.

Conclusion
The primary motivation for this work was to provide a theoretical justification for the superiority of the “Vardon Swing”, in particular as it is propounded in Reference [2]. I believe that aim has been satisfied. It remains a mystery as to why this approach to the golf swing has received so little attention from the golf profession. However, in the process a spreadsheet has been developed, which provides a useful tool for investigations of the golf swing, and which can be replicated by anyone with the necessary mathematical basics. All manner of “what if” exercises can be performed (changing the club, altering the total time of the swing, changing the allowable torques, examining the effect of gravity and so on).
----------------------------------------------------------------


DG

I can imagine that clubhead speed could be faster if the left arm bends 90 degrees at the left elbow joint because there are now two potential points (left elbow and left wrist) where lag can be created and released in the 3-lever system. However, I cannot imagine how a golfer can reliably control the release of those two hinge points to consistently get the appropriate amount of forward shaft lean and a square clubface at impact. Jack Kuykendall created a bent left elbow model golf swing, but he kept the left wrist straight (unhinged) so his model is a 2-lever model, and not a 3-lever model.


Jeff.

[dubiousgolfer]

Dr Mann

Just found this video with TPI co-founder Dave Phillips who is advocating  proposing 3 things to create clubhead speed for those who have injury or problems getting a full backswing.

www.facebook.com/meandmygolf/videos/493425198066238/

1. The internal rotation of the left femur in the backswing , knee pointing behind the ball and the left heel raised - to create a bigger backswing .
2. The bending of the lead arm.
3. Experimenting with ball position and height while making these changes.

You mentioned the following:

"I cannot imagine how a golfer can reliably control the release of those two hinge points to consistently get the appropriate amount of forward shaft lean and a square clubface at impact"

Why would the above be the case if the golfer applied a strong grip and was still able to move his shoulder downplane enough so he didn't 'run out of right arm' and still retain an extended trail wrist into/through impact?

DG

PS.  Also looking at the MOF forces created as the left arm straightens , won't that create a force across the shaft in the early downswing which will cause a 'lagging' MOF ? Therefore the golfer is pulling down and 'out' (ie. away from the target as the left arm straightens)  in the early downswing , creating lots of linear speed (along the hand path)  with pivot/shoulder girdle & left tricep extension, while still retaining lag.

Strangely enough , just looked at my own swing video posted here and my left arm is decidedly bent - maybe I need to bend it some more 

[imperfectgolfer]

Bending the left arm by 30 degrees is not a problem in terms of timing the straightening the left arm during the downswing, but bending the left arm by 90 degrees (as recommended by Jack Kuykendall) is a problem. I am not surprised that pro golfers do not use that technique.

I don't know why a strong left hand grip should affect my thinking on this topic.

Jeff.

[dubiousgolfer]

I've just tried the 90 degree arm bend swing in my back garden but managing the radius of the swing near impact by straightening the left arm is very problematic indeed. The timing required to perfect this type of swing is too difficult.

DG