Invisible Exertions

[mandrin]

We have instruction and the result, a golf swing. Instruction is bewildering in its variety but yet the resulting swings remarkable similar. When someone demonstrates hitting and swinging quite likely it will be difficult to notice any difference even with close scrutiny. What feels as totally different swings will be judged by an onlooker as being the same. Is this only a matter of feel or is there more to it?

Most golf instruction nowadays teaches to start the down swing from the bottom up and referring to the kinetic chain action for the desired progressive transfer of momentum / kinetic energy from the ground up to the clubhead. However there are still quite a few who think/thought of the lower body as a stable platform and feel the action to be in the hands/arms.

Tommy Armour - “The action is that of whipping the clubhead through the ball with the hands. Not slapping it, waving at it, flinging it, stiff-arming it, but whipping it with a tigerish lash.”

Ernie Vossler - “Although it may sound outrageous it's my belief that no one can hit too soon. I don't think anyone can unlock his wrists and release the clubhead too early..... ”

Peter Croker - '' The hands are the source of motion of the club, arms, shoulders, hips and legs - all the way down to the base of your feet. “

Tom Tomasello's - down and out right arm action.

Mark Evershed - clubhead velocity contribution: body 4.6 %, hands 60 %.​

Since the swings of these instructors don't show an early release as is indeed the case for amateurs when starting the downswing with heir hands, they must doing something to prevent this early release to happen. One possibility is that they teach one thing and do another. But that is the easy way out of this dilemma.

Well known golf science authors such as Cochran et al and Jorgensen were convinced that the major source of power comes from the contribution of the big muscles and perhaps influenced the opinion of golf kingdom towards their point of view. They did however overlook the contribution of the linear joint reaction forces, hence their opinion carry less weight.

Even if indeed very simple, an analysis, using a double pendulum model, like Iron Byron, shows nevertheless some light on this issue. It shows that an active hand release action can be neutralized by an appropriate torque developed by the core.

This problem of invisible exertions makes golf indeed so utterly frustrating for many. Seeing a beautiful simple looking swing one just can't reproduce it, even if spending much effort, as we usually don't have a clue about the invisible exertions to required to produce it.

 

[Michael Finney]

good to have you back for a visit

 

[Jared Willerson]

Are Vosler et al, discussing unbending the right elbow perhaps?

 

[Michael Finney]

so...using your double pendulum iron byron model, "swinging" and "hitting" can be mutually exclusive but if the torques follow your graphs, the two "swings" will be indistinguishable....sounds good

but since there is no dead stop in our wrists, would a human being need to adjust the magnitude of the positive torque2 to replicate your results?

 

[mandrin]

so...using your double pendulum iron byron model, "swinging" and "hitting" can be mutually exclusive but if the torques follow your graphs, the two "swings" will be indistinguishable....sounds good

but since there is no dead stop in our wrists, would a human being need to adjust the magnitude of the positive torque2 to replicate your results?

Michael,

What is shown is based on mathematics not necessarily meant to be duplicated by a human golfer.

Fig3a shows the torque required to model a mechanical dead stop in the math model.

A human golfer, once his wrists fully cocked, is not far away from a mechanical dead stop.

 

[birly-shirly]

nice work Mandrin.

I understand that this is a model - and that you've chosen quite extreme examples to prove what is possible.

So, this is just an observation and a question on the use of your model.

Of the 2 swings, I can see mostly reasons to try to use the "ground up" swing. The variables seem so much easier to control. The variable torque at the wrist could come from a left wrist fully cocked at the top of the swing. The torque around the central pivot is a constant.

In the "top down" swing you have to apply a variable torque - low, then increasing, then decreasing, then increasing again and finally decreasing - all between the transition and impact. Wow - that would be some timing issue. Not only that, but the peak torque required in the "top down" swing is actually higher than the constant torque applied in the "bottom up" swing - so in one sense you could argue that the "top down" swing is less "efficient" (in a loose sense of the word, assuming that the limiting factor for a golfer is the amount of peak torque that they can generate)

I don't think that Jorgenson claimed that his model was the only way to swing a club - but I think he was attracted by the apparent simplicity of a model with a constant "core" torque, a hard stop at the wrist and a lateral shift - all of which combined could accurately replicate the actual performance of a real swing.

Have you given any thought as to whether the pattern of variable torque in the "top down" swing would be practical?

Also, have you looked at any "middle ground" variations where there is, e.g. a smoother curve for the core torque which matches well with a smooth curve for the wrists doing some positive work?

If there were biomechanical reasons why it might be more difficult to apply a constant core torque than an increasing one, then I can see how your model might really come into its own.

Thanks for posting this.

 

[Virtuoso]

Mandrin, I've run into some of your older posts while searching for info and I've always really enjoyed them. I really appreciate the effort and time it must take to put this together.

Given your statement below:

...that even a very simple Iron Byron golf instructor could mystify his students telling them to use active wrist torque throughout the whole down swing, and indeed actually doing it, but likely not knowing himself that it takes a rather special torque, developed at the core, for his students to imitate his nice looking swing.

I would say that in terms of its practical application to golf instruction, especially with the choppers, that "rather special torque" is a severe understatement. It is so unique that you might just as well have given me half the combination to a lock and told me to trust empiricism for the rest....and then check back with me 20 years later.

So, my take would be that, regardless of their intentions and sincerity, Ernie and the gang have done an injustice to teaching....at least in terms of teaching your everyday Joe.

 

[Bonesy]

90 degree stop

Does figure 3a imply that some material torque is needed to acheive/maintain the 90 degree stop? ie, if there were no positive torque, our wrists could get driven over 90 degrees and thus result in a very different swing?

 

[mandrin]

nice work Mandrin.

I understand that this is a model - and that you've chosen quite extreme examples to prove what is possible.

So, this is just an observation and a question on the use of your model.

Of the 2 swings, I can see mostly reasons to try to use the "ground up" swing. The variables seem so much easier to control. The variable torque at the wrist could come from a left wrist fully cocked at the top of the swing. The torque around the central pivot is a constant.

In the "top down" swing you have to apply a variable torque - low, then increasing, then decreasing, then increasing again and finally decreasing - all between the transition and impact. Wow - that would be some timing issue. Not only that, but the peak torque required in the "top down" swing is actually higher than the constant torque applied in the "bottom up" swing - so in one sense you could argue that the "top down" swing is less "efficient" (in a loose sense of the word, assuming that the limiting factor for a golfer is the amount of peak torque that they can generate)

I don't think that Jorgenson claimed that his model was the only way to swing a club - but I think he was attracted by the apparent simplicity of a model with a constant "core" torque, a hard stop at the wrist and a lateral shift - all of which combined could accurately replicate the actual performance of a real swing.

Have you given any thought as to whether the pattern of variable torque in the "top down" swing would be practical?

Also, have you looked at any "middle ground" variations where there is, e.g. a smoother curve for the core torque which matches well with a smooth curve for the wrists doing some positive work?

If there were biomechanical reasons why it might be more difficult to apply a constant core torque than an increasing one, then I can see how your model might really come into its own.

Thanks for posting this.

birly-shirly

It is not very easy for a human golfer to duplicate these math generated torques. It is very difficult in a golf swing to even maintain a constant torque for the same reason that when pushing a cart and speeds picks up you can't push as hard. Feel wise you might however even think to do just the opposite.

What you should retain is the general trend – swinger, early effort and coasting through impact - hitter, gentle start and explosive effort through impact area. Both are valid ways to swing a club. Probably also a matter of personality. A controlling/aggressive person will be better off hitting.

I have used various torques for both core and wrists for various reasons but that is back down in the archives. The real torques measured on golfers show typically very complex patterns and moreover are very individual. When you really go for a hitting procedure you will automatically produce something like Fig2b without any second thought.

 

[greenfree]

Mandrin, is this former post of yours the same as what your saying in this thread? Excuse my ignorance just trying to grasp what your saying. Is there seperate pure hitting and pure swinging procedures or a combination of the two in various golfswings?



Brian,

Swinging and hitting action feels perhaps very different. However are they really so different as put forward in TGM?

Any extension action along the action line AE is equivalent mainly to a torque around C and partly to a torque around D. A model has no feelings and hence 'sees' swinging and hitting to be largely the same. Particularly if one hits with the wrist bone of the trail hand, minimizing dx, there is indeed very little difference between hitting and swinging. The restrictive checkrein action, due to the triangular structure of shoulders and arms in a swing, makes hitting and swinging to be rather similar actions.

I agree that this mutual exclusive TGM idea of only either hitting or swinging is simply folklore and better be left alone to collect dust. It just boils down to using as many muscles as possible to generate torque efficiently, hence being an efficient swatter.

 

[mandrin]

To give people some feel for torques of real golfers, shown some measurements of wrist torques taken from 'A THREE DIMENSIONAL KINEMATIC AND KINETIC STUDY OF THE GOLF SWING' , Steven M. Nesbit



"Figure 9 illustrate the alpha component of the torque applied to the grip respectively for the four subjects."

"The subjects exhibited alpha torque profiles that were both unique and consistent among trails revealing a alpha torque “signature” for each subject. Two distinct swing styles were revealed however. The scratch and 5 handicap subjects were “hitters” appearing to exert considerable effort in swinging the club. Their alpha torques increased significantly during the downswing and reached large maximum values at the midpoint of the downswing. These maximum values were maintained until close to impact. The other two subjects were “swingers” with a swing style that was smooth and appeared almost effortless. Their maximum torques were much lower and the curves had smaller variations during the downswing."

 

[mandrin]

Does figure 3a imply that some material torque is needed to acheive/maintain the 90 degree stop? ie, if there were no positive torque, our wrists could get driven over 90 degrees and thus result in a very different swing?

Bonesy
The modeling is done in this case to simulate specifically a mechanical dead stop. However anything can be modeled, like for instance no restraint whatsoever and then indeed the down swing is quite different. There will be then back knifing going on in the first portion of the down swing. You can easily verify for your self by creating a rather dynamic recoil at the transition, with wrists not quite fully cocked, and you will feel the club really exerting some significant stress on your wrists joints.

 

[mandrin]

Mandrin, I've run into some of your older posts while searching for info and I've always really enjoyed them. I really appreciate the effort and time it must take to put this together.

Given your statement below:

...that even a very simple Iron Byron golf instructor could mystify his students telling them to use active wrist torque throughout the whole down swing, and indeed actually doing it, but likely not knowing himself that it takes a rather special torque, developed at the core, for his students to imitate his nice looking swing.

I would say that in terms of its practical application to golf instruction, especially with the choppers, that "rather special torque" is a severe understatement. It is so unique that you might just as well have given me half the combination to a lock and told me to trust empiricism for the rest....and then check back with me 20 years later.

So, my take would be that, regardless of their intentions and sincerity, Ernie and the gang have done an injustice to teaching....at least in terms of teaching your everyday Joe.

Virtuoso,
Don't look at the fine details, just the general trend suggested. I am sure that you have never seen time histories of torques of real golfers. They are indeed much fancier than the the smooth ones I have used in the modeling.

 

[Ringer]

It seems to me the more the arms trail the pivot, the further the pivot has to turn in order to get the hands to impact.

But if the arms are more active, the pivot can stall and the double pendulum action is more useful.

In other words, if your hands are working off your right hip for impact then you need a lot of pivot. If your hands are extending out to in front of your left hip, then you need some pivot stall or at least faster arms.

 

[Virtuoso]

Virtuoso,
Don't look at the fine details, just the general trend suggested. I am sure that you have never seen time histories of torques of real golfers. They are indeed much fancier than the the smooth ones I have used in the modeling.

Mandrin, yes, I understand. I have seen an idealized traction circle, and then the actual G-G-V diagram of a Formula One car performance envelope, and clearly, the actual data is fantastically more complicated than the model. I understood that to be the case in your model as well.

I don't think I explained myself as well as I could have. In an effort to take the theory and make practical use of it in my mind and my teaching, I envisioned two instructors: a "relax your hands and just turn your body to the left" type teacher, and an Ernie Vosler "you can't release too soon" type teacher.

The student watches both teachers demonstrate the swing. If the student follows the first teacher's advice, he has some chance to replicate the swing, especially since he is really only worried about replicating one constant torque at the "central hub". On the other hand, if he follows Ernie's advice about a constant torque at the wrists from the very beginning, he has to worry about that AND the mysterious torque that Ernie has also applied at the central hub....which Ernie has neglected to mention out of his own ignorance.

So, in that sense, Ernie's central hub torque is quite unique. The student will naturally supply his own complicated and individual torque at the central hub to balance the wrist torque, but will he be able to produce the results that Ernie does? What does Ernie say when the guy lays the carpet over the ball? "Just keep pushing that right elbow straight...you'll get it...sometime in the next century."

 

[mandrin]

Mandrin, yes, I understand. I have seen an idealized traction circle, and then the actual G-G-V diagram of a Formula One car performance envelope, and clearly, the actual data is fantastically more complicated than the model. I understood that to be the case in your model as well.

I don't think I explained myself as well as I could have. In an effort to take the theory and make practical use of it in my mind and my teaching, I envisioned two instructors: a "relax your hands and just turn your body to the left" type teacher, and an Ernie Vosler "you can't release too soon" type teacher.

The student watches both teachers demonstrate the swing. If the student follows the first teacher's advice, he has some chance to replicate the swing, especially since he is really only worried about replicating one constant torque at the "central hub". On the other hand, if he follows Ernie's advice about a constant torque at the wrists from the very beginning, he has to worry about that AND the mysterious torque that Ernie has also applied at the central hub....which Ernie has neglected to mention out of his own ignorance.

So, in that sense, Ernie's central hub torque is quite unique. The student will naturally supply his own complicated and individual torque at the central hub to balance the wrist torque, but will he be able to produce the results that Ernie does? What does Ernie say when the guy lays the carpet over the ball? "Just keep pushing that right elbow straight...you'll get it...sometime in the next century."

Virtuoso

The gist of my post is not to delve into all the fine points of the instruction of each and every instructor and scrutinize if it is valid, but simply to try to give people a handle, a possible explanation, why several instructors, like for instance Peter Croker, teach one thing but yet seemingly do something else. A paradox which has intrigued many golfers for a long time.

 

[birly-shirly]

birly-shirly

It is not very easy for a human golfer to duplicate these math generated torques. It is very difficult in a golf swing to even maintain a constant torque for the same reason that when pushing a cart and speeds picks up you can't push as hard. Feel wise you might however even think to do just the opposite.

What you should retain is the general trend – swinger, early effort and coasting through impact - hitter, gentle start and explosive effort through impact area. Both are valid ways to swing a club. Probably also a matter of personality. A controlling/aggressive person will be better off hitting.

I have used various torques for both core and wrists for various reasons but that is back down in the archives. The real torques measured on golfers show typically very complex patterns and moreover are very individual. When you really go for a hitting procedure you will automatically produce something like Fig2b without any second thought.

Thanks for taking the time to explain. I completely agree, although it's not really a matter of physics, that once you move into real world actions there will be more going on than any of us can consciously control or even monitor.
Thus, anyone who focusses on throwing the club with their wrists from the top of the swing, if that's what Ernie Vosler was advocating - still inescapably knows that they have to deliver the club to the ball with some speed. Inevitably, the arms, torso and legs are going to co-ordinate with the hand action to produce something that looks like a golf swing, rather than the waving of a flag.

I also think you're saying that the apparent attraction of Jorgensen's model - based on the simplicity of a constant torque around the hub - is maybe not so simple or attractive (certainly not conclusive) in the real world of flesh and bones. If that is what you're saying, it's a very good point.

The other point I wanted to ask was this. You said:

Well known golf science authors such as Cochran et al and Jorgensen were convinced that the major source of power comes from the contribution of the big muscles and perhaps influenced the opinion of golf kingdom towards their point of view. They did however overlook the contribution of the linear joint reaction forces, hence their opinion carry less weight.

It was my understanding of Cochrane/Jorgensen that they looked at the overall amount of work done in accelerating the clubhead from the top of the swing to impact - and concluded, based on assumptions about efficiency and power output per mass of muscle, that there simply isn't enough muscle mass acting directly on the hands and arms to generate the power found in an effective golf swing. In other words, they weren't assuming "big muscle power" because of any particular delivery mechanism - they just couldn't find sufficient muscle mass to produce the power output of a good golf swing anywhere else in the body.

Do you think that through the use of linear joint reaction forces you can identify sufficient muscle mass acting on the club to power a good swing without having to look to the active participation of the largest muscles? Or, do you think that Cochrane/Jorgensen were mistaken and overestimated the amount of muscle mass required?

 

[Virtuoso]

Virtuoso

The gist of my post is not to delve into all the fine points of the instruction of each and every instructor and scrutinize if it is valid, but simply to try to give people a handle, a possible explanation, why several instructors, like for instance Peter Croker, teach one thing but yet seemingly do something else. A paradox which has intrigued many golfers for a long time.

Ok Mandrin, gotcha, thank you. I guess I was anxious to try to find any possible implications that may arise from the analysis.

Do you think your analysis implies anything other than just the underlying nature of the paradox?

 

[mb6606]

"Both are valid ways to swing a club. Probably also a matter of personality. A controlling/aggressive person will be better off hitting."

Madrin you are slipping.

 

[dbl]

Mandrin can you clarify the wrist torque?

Is it a torque related to forces around an axis like from elbow to wrist, or is related to uncocking (or the restraint) of the wrist and club handle? I think the latter and most of the high torque is for maintaining lag of the cocked wrist/club.

Thanks.