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Optimising Clubhead Speed - Is this the real way?


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On 5/23/2022 at 5:29 AM, Wildthing said:

 

We seem to see patterns in ground reaction forces (like in the Mark Crossfield video) , that if somehow changed does seem to increase clubhead speed, so maybe it doesn't matter but I'd like to know the physics involved. 

Maybe the lateral motion is a precursor to increased vertical ground reaction force but what exactly is happening?  How does it effect the timing, magnitude and direction of the forces applied via the hands on the grip?  If we knew, then maybe golf instruction could be targeted better.

PS. Even if we increased our clubhead speed , it won't guarantee we will hit the ball solidly, so it all has to be matched up.

 

Good morning Wildthing.  I think the answer to your question is rather simple if you look at the "BODY" of the golfer as "Mass". When the body of mass is moving toward the target, that body of mass has momentum. and that added momentum is attached to the golf club via the hands. So the simple answer is that this added momentum increases the "Total" amount of energy that the golfer can apply to the back of the golf ball at impact.  It's the same thing you see in baseball  when a hitting takes a step toward the pttcher as he starts to swing the bat. His body mass adds energy to his swing and he can hit the ball farther using this step toward the pitcher and the ball.  I hope this makes sense to you the same way it makes sense to me. Let me know what you think of what I just posted. 

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22 hours ago, IONEPUTT said:

I watched the Mark Crossfield video and didn't learn a thing. Then I watched a second one where he was taking a lesson from Mark Bull, and it that video I learned what Mark Bull was having Crossfield doing, And that was when I learned HOW Crossfield had changed his swing and how he had increased his swing speed.  The second video was well worth the time and I will be watching more of Mr. Bulls videos in the future to see what I can learn from him and with any luck I can use his instruction and add a few more MPH's to my swing speed soon. I would love to get my 105-108 MPH up to over 110 on a steady basis and enjoy the added distance off the tee. I've been up over 120 a few times but it was only a FEW times so learning how to do it on command would be great way to kick off a new golf season this spring. 

I think this is a better video that explains the lateral, rotational, and vertical forces that help increase speed.  

 

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Thank you for the link cnosil. Great video explaining the ideas of moving the body in different directions.  I can clearly see how this would help to create speed in the swing, but I can also see how it could cause some major problems in consistency. There are all kinds of ways this movement could be a problem as it all has to happen at the right time in the swing. It explains why so many long hitters can hit the ball long, but it also explains why they can have a really bad day if their timing or sequence is off just a small amount. I wonder how long it would take a good golfer to get the timing right and be consistent with said timing?  One thing I will say is that watching this video makes me want to have one of those weight/balance plates to stand on to see how I weight my feet during the swing. 

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I just went to the Swing plate site and found out the "Price" for one of those force plates. NOT in my budget this year for sure. My car didn't cost as much as what they want for these plates. 

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On 5/18/2019 at 9:40 PM, Shankster said:

I have no idea what your saying. But it’s cool.

My though on DJ getting the straight path is because belly button is facing the target before his club is anywhere near the ball.

That 4D model of him today at the PGA was nuts. If I tried to turn that fast, far, and powerful I’d be in a wheel chair.

Has to be a super hero, that’s the only way to explain it.

he's dropped his right elbow onto his hip and is whipping thru with his body

On 5/24/2022 at 12:33 PM, IONEPUTT said:

I watched the Mark Crossfield video and didn't learn a thing. Then I watched a second one where he was taking a lesson from Mark Bull, and it that video I learned what Mark Bull was having Crossfield doing, And that was when I learned HOW Crossfield had changed his swing and how he had increased his swing speed.  The second video was well worth the time and I will be watching more of Mr. Bulls videos in the future to see what I can learn from him and with any luck I can use his instruction and add a few more MPH's to my swing speed soon. I would love to get my 105-108 MPH up to over 110 on a steady basis and enjoy the added distance off the tee. I've been up over 120 a few times but it was only a FEW times so learning how to do it on command would be great way to kick off a new golf season this spring. 

swinging hard=less clubhead speed, swinging fast and insync =increased clubhead speed

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Love this topic.  When it comes to optimizing clubhead speed and specifically the hands like you are talking about, there are two key things that stand out in my mind.  I think one of the main issues in translating anything golf related into action is that the mechanical "how" of doing things often gets mixed in and confused with the motor control "how" of doing them. One is a set of instructions to accomplish a certain movement, the other, the parameters to accomplish a certain movement without completely guided instructions.

Optimizing hand and club speed requires a good hand path plane into the ball, as any manipulation will cause a slowing down of the hands and club.  And also, giving ourselves the motor control parameters needed to allow us to create the proper forces that are applied with the hands to the club.  Not a mechanical instruction list of how forces are applied, but the parameters of how to create the wanted actions, without having to "try" to apply them through mechanical control. 

One of the first things that good golfers do, that amateurs don't, has to do with how the pelvis or "hips" move.  What's this have to do with the hands, well, where the lower body goes, the upper body and arms will follow.

The first problem is that most amateurs think about turning their "hip" sockets in the backswing. What they actually do is move at the waist.  This generally leads to a standing up move, flat hip plane, and from there its either throw it over or slide under to get back to the ball.

Instead of moving their "hips", most pros move their pelvis and do so with the rotation occurring at the hip socket around the top of the femur.  They are rotating their pelvis into their rear leg. If you look at all the pictures posted in this thread, you'll see each players leg mostly pointed straight forward with their pelvis turning into it.  This move is important to hand path, because the hands will follow where the body leads (as long as you turn your body).  In the downswing, this position is held and then instead of turning the "hips", most pros turn their pelvis into the lead leg.  Cameron Champ is a great example of this.  This move allows the "hips" to move on an inclined plane and this inclined plane allows for the upper body to move within a good plane.

This pelvis move is the basis for a good upper body move, allows for t-spine rotation (as opposed to the body turning from the waist area) and when done properly translates to a great stretch shorten cycle that allows for proper force application with the hands.  Which leads me to my second key to maximize force production, the "how" of how we get to the top and actually get that force.

My number two issue for most golfers trying to maximize this is that they overly controlling their swing and movements.  If you are someone that is constantly concerned with hitting positions in the backswing, as most golfers are, you will forever struggle with golf.  If you are setup well, have a proper grip, and can turn your pelvis as opposed to your waist, all you need is a cue to start the swing and allow the body to turn.

The backswing starts with a tensing of the muscles.  As soon as this cue initiates the swing back, there is a relaxation period of the muscles on the way to the top. As the club reaches the top and the downswing begins there is another tensing of the muscles to initiate the downswing, then relaxation, and then application of the swing at the ball with more tensing of the muscles.  The key in all of this is the relaxation part. Most golfers don't have any at the right times and it's crucial to speed. 

If you muscle and control your backswing (or downswing for that matter), your body will never have the opportunity to properly brace the club with the trail hand (as Sasho describes) and transfer it to the club properly. The best way to think about it is that you are throwing everything back to the top, stopping the throw, reversing it, and then applying at impact.  If you can do this and turn your pelvis correctly, you will be setup to maximize your club speed.

 

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I liked the first few posts, which seemed to make a lot of sense.

lost me with the Doctor....

but I still like this topic and will try to think through it more.

thanks,

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OK, so there's a tendency for golfers looking at swings to focus on minutiae, to not see the forest for the trees. Here is Sasho MacKenzie's most recent research, which is just about as simple as it can be in terms of what a golfer has to do to maximize clubhead speed. (https://www.golfsciencejournal.org/article/12640-how-amateur-golfers-deliver-energy-to-the-driver) BTW, when I said "simple", I didn't mean you don't have to know physics or math. It is a very simple explanation in terms of the physics needed.

The message from the study is that the most effective way to get clubhead speed is to maximize the work done along the hand path. In physical terms, work means force in the direction of motion. So it is the component of the force (not torque couple) the hands apply to the club in the direction of the hand path, integrated over the hand path from transition through impact.

If you are familiar with physics and math, this is a very simple statement of what you have to do. If not, let me suggest a similar goal that will probably be the same in practice. (If Sasho is on this forum, I'll be glad to defer to him as to whether this is accurate.) During the downswing, move the hands along the hand path as fast as possible. Not the release of the clubhead nor any slap at the ball; torque applied to the grip during the downswing is pretty ineffective in producing clubhead speed.

If you are doing this and want even more clubhead speed, you might try a longer hand path (bigger turn). That works better than trying for more wrist cock, according to Dr Sasho.

I have said nothing about what the hips, the feet, the glutes, the trail pinkie need to do to make this happen. That is technique, which may be different for different golfers, or starting from a different swing. But the goal is clear: accelerate the hands to the maximum possible speed all through the downswing.

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Posted (edited)
14 hours ago, Dave Tutelman said:

OK, so there's a tendency for golfers looking at swings to focus on minutiae, to not see the forest for the trees. Here is Sasho MacKenzie's most recent research, which is just about as simple as it can be in terms of what a golfer has to do to maximize clubhead speed. (https://www.golfsciencejournal.org/article/12640-how-amateur-golfers-deliver-energy-to-the-driver) BTW, when I said "simple", I didn't mean you don't have to know physics or math. It is a very simple explanation in terms of the physics needed.

The message from the study is that the most effective way to get clubhead speed is to maximize the work done along the hand path. In physical terms, work means force in the direction of motion. So it is the component of the force (not torque couple) the hands apply to the club in the direction of the hand path, integrated over the hand path from transition through impact.

If you are familiar with physics and math, this is a very simple statement of what you have to do. If not, let me suggest a similar goal that will probably be the same in practice. (If Sasho is on this forum, I'll be glad to defer to him as to whether this is accurate.) During the downswing, move the hands along the hand path as fast as possible. Not the release of the clubhead nor any slap at the ball; torque applied to the grip during the downswing is pretty ineffective in producing clubhead speed.

If you are doing this and want even more clubhead speed, you might try a longer hand path (bigger turn). That works better than trying for more wrist cock, according to Dr Sasho.

I have said nothing about what the hips, the feet, the glutes, the trail pinkie need to do to make this happen. That is technique, which may be different for different golfers, or starting from a different swing. But the goal is clear: accelerate the hands to the maximum possible speed all through the downswing.

 

Hi Dave

But what hand path is the optimal hand path? Say the golfer reaches the top of the backswing and then pulls his hands straight down as fast as possible, that could cause a positive MOF and early release. This is why I thought a good feeling for the golfer was to try and pull the grip off the shaft (from top of backswing all the way through impact) so that the net force applied via the mid-hand-point  is directed closer to the COM of the club in the early-mid downswing (with a smaller moment arm to prevent early uncocking of the lead wrist). Basically, shouldn't the hand path in the early downswing be as least curved as possible to minimise divergence between the hand and club COM paths?

For example, here is Jamie Sadlowski at the top of the backswing.

 

8ZCHTI0MG557.png

 

If JS tried to pull his lead hand down as fast as possible in the direction of the red arrow he would early release unless he applied other forces to the grip to prevent that from happening. Obviously, I have exaggerated the scenario above, but if a golfer had a wrong perception of hand path and actually did the latter, you can see that the COM of the club would tend to rotate and try and align itself with the tail end of that red arrow net force vector.

Therefore, a golfer, especially those that are not acquainted with the physics of the situation, may need guidance on how to optimise his/her hand path to prevent early release. 

 

 

Edited by Wildthing
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Posted (edited)
On 5/24/2022 at 5:52 PM, IONEPUTT said:

Good morning Wildthing.  I think the answer to your question is rather simple if you look at the "BODY" of the golfer as "Mass". When the body of mass is moving toward the target, that body of mass has momentum. and that added momentum is attached to the golf club via the hands. So the simple answer is that this added momentum increases the "Total" amount of energy that the golfer can apply to the back of the golf ball at impact.  It's the same thing you see in baseball  when a hitting takes a step toward the pttcher as he starts to swing the bat. His body mass adds energy to his swing and he can hit the ball farther using this step toward the pitcher and the ball.  I hope this makes sense to you the same way it makes sense to me. Let me know what you think of what I just posted. 

 

Hi IONEPUTT

I'm not sure it's as simple as that in the golf downswing (I wish it was!).

If you have the book ' The Physics Of Golf' , Theodore Jorgensen provides a possible reason how a lateral movement of the hub of a double pendulum (used to model the golf swing) can cause an increase in clubhead speed.

I did email Dr Scott Lynn about lateral movement caused by ground reaction forces and how they could influence clubhead speed and this was his reply:

"Thanks so much for your email.  You ask some really good questions that I don’t think anyone has the answers to yet.  I’m not aware of any published work that has been done to date where the GRFs have been measured on the same swings where club inverse dynamics analyses were run so that the calculated club/hands kinetic values could be related to the measured GRFs.  Hopefully this type of work will happen soon as this would really help our understanding of golf swing mechanics.

 My hypothesis would be that creating more horizontal braking GRF from the ground could result in some of that force (directed away from the target) being transferred through the body and to the club in the late downswing (as this is when we see the peak horizontal braking GRF in high speed swingers).   It is interesting to note that in a few of the fastest long drive competitors in the world that I have had the opportunity to measure, the horizontal braking GRF peaks at the same time as the vertical GRF.  If the golfer is able to peak the vertical and horizontal braking GRFs at the same time and transfer these forces through the body to the club, this could result in the net force on the club having a large magnitude and being directed more away from the target in the late downswing, thus increasing the moment arm between the line of action of the net force and the center for mass of the club.  This would increase the in plane moment of force during the late downswing, when Dr. Mackenzie’s work has shown us that this particular moment is dominant in speeding up the club (the CoM of the club trying to “line up” with the line of action of that force vector). 

I have made a quick figure using one of Dr. Mackenzie’s animations to illustrate my point (see attached).  If the purple vector is the net force applied to the club in the late downswing by a golfer with limited horizontal braking force, the blue vector would be my hypothesized net force vector applied to the club if horizontal braking GRF was increased in the late downswing.  By using the horizontal braking GRF to lean this net force vector away from the target more, this would increase the moment arm distance (estimated in red…hard to do in 2D but you get the idea) and hence the in-plane moment of force and speed the club up as it heads into impact.

Again this is just a hypothesis at this point and I’m open to other ideas and/or being proven wrong. "

image.png.ddb92dad3a0cc8c9a5cd1fc6d106f20b.png

Edited by Wildthing
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Posted (edited)

Here's a better video discussing the ground reaction forces, the timing of the peaks in some kinetic sequence (Horizontal, Torque, Vertical) and also some tweaks one can do to try and modify the timing.

 

Will be interesting to see some more recent videos of pros with their new Swing Catalyst dual plates which measure the ground reaction forces for each foot rather than the net effect in these graphs.

I can also appreciate what  IONEPUTT posted before when he said

"I can also see how it could cause some major problems in consistency"

For example, maybe too much 'lateral/torque/vertical' grfs (and even too much speed) might affect the golfers ability to hit the ball square on the sweet spot.  Also , didn't Tiger previously snap his lead leg straight in the late downswing to generate clubhead speed? Makes one wonder whether that need for speed contributed to his knee injuries.

Edited by Wildthing
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Posted (edited)

I'd like to raise a question regarding what Dave Tutelman mentioned in his previous post:

" During the downswing, move the hands along the hand path as fast as possible."

How does this that tie in with the force velocity curve for muscle contraction (see below)?

Doesn't this mean trying to move the arms/hands down the hand path as fast as possible will indirectly decrease the potential force the arms/hands can apply on the club?

Doesn't this mean the golfer would be more likely to increase the magnitude of the force via his arms/hands, especially in the early downswing, if the golfer is moving the whole upper body/club unit (ie. torso/shoulders/arms/hands/club) with the core muscles that may move slower but be able to produce a higher force?

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

What is the Force-Velocity Curve?

Though the force-velocity curve may appear confusing and complicated, it is actually very straight-forward. The force-velocity curve is simply a relationship between force and velocity and can, therefore, be displayed on an x-y graph (Figure 1). The x-axis (i.e. horizontal axis) indicates velocity, for example, this may represent muscle contraction velocity, or velocity of movement (measured in meters per second). Whilst the y-axis (i.e. vertical axis) indicates force, for example, this may represent muscle contractile force, or the amount of ground reaction force produced (measured in Newtons).

Figure-1-The-Force-Velocity-Curve.png

 

The curve itself shows an inverse relationship between force and velocity, meaning that an increase in force would cause a decrease in velocity and vice versa. Giving an example, a one repetition maximum (1RM) Back Squat would produce high levels of force but would be lifted at a slow velocity. While a countermovement jump (CMJ) would produce a high movement velocity, it would also only produce low-levels of force. This indicates that there is a trade-off between force and velocity. That being, when an exercise produces high levels of force, it will also produce a slow movement velocity and vice versa.

This trade-off between force and velocity is thought to occur due to a decrease in the time available for cross bridges to be formed – more time, equals more cross bridges, and more cross bridges mean a greater contractile force (1). Therefore, slower velocity exercises allow the athlete to form more cross bridges and develop more force. Higher velocity exercises provide less time for cross bridges to form, and therefore results in lower force production.

 

I thought I may as well add this AMG video too which provides some interesting comparisons between pros and amateurs and also how they increased the clubhead speed of a specific amateur (before and after).

It seems that the amateurs perception of the golf swing was responsible for his smaller clubhead speed (ie. see below).

1. Leave hands up

2. Passive arms

3. Rotate hard

 

 

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Manual De La Torre - 'Understanding the Golf Swing' & Harvey Penick's 'Little Red Book' two great books on the golf swing for us ordinary golfers without a physics degree. 😉

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29 minutes ago, dcorun said:

Manual De La Torre - 'Understanding the Golf Swing' & Harvey Penick's 'Little Red Book' two great books on the golf swing for us ordinary golfers without a physics degree. 😉

I think I mentioned this earlier, I think understanding all of the technical stuff is an asset for an instructor to understand, but for most players it's almost a detriment.  Most players need to find the feels and images and do the drills that produce an efficient swing.  The instructor is the bridge between the technical "physics" of the golf swing and the end user.  

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Posted (edited)

Here's another image that Dr Kwon produced showing the typical 'in plane net force' (black vector arrow) applied via the mid-hand-point on the grip in the downswing.  Now this is weird because it shows that force across the club in the downswing (from Top of Backswing TB -> ED club vertical) that creates a negative moment of force (torque) which will tend to rotate the clubhead clockwise (from a face-on view) and retain the lag angle between the clubshaft and lead arm. 

I don't think it's likely caused by the lead hand (although that might be possible) but probably via the trail hand as mentioned in Dr Sasho MacKenzie's videos.  The problem is to try and explain what pro golfers could be doing to generate that net force across the club in the early downswing.

 

NT-KwonTangentialRadial.jpg

 

 

Here again we have another idea of how lag angle can be retained via forces at the grip that may contribute to greater clubhead speed during release. There seems to be many different explanations for the creation of clubhead speed which, to be honest, can be very confusing. In my humble opinion, it all needs to be put together in some logical fashion if possible.

1. Faster Backswing (Dr Sasho MacKenzie)

2. Longer hand path to apply more linear work (Dr Sasho Mackenzie)

3. Create max hand speed earlier in the downswing (Athletic Motion Golf)

4. Creation of 'Stretch Shorten Cycles' at the joints from ground up using a kinematic sequence proximal to distal (Dr Greg Rose/Dr Phil Cheetham)

5. Optimised hand path (Dr Steven Nesbit)

6. Ground reaction forces tied in with a kinetic sequence 'Horizontal/Torque/Vertical' (Dr Scott Lynn) 

7. Maximising the velocities of the arms/shoulders/ribcage/pelvis at the same time in the downswing (Dr Kwon)

8. Net force across the mid-hand-point to retain the lag angle as shown in Dr Sasho MacKenzie videos and Dr Kwon diagrams.

9. Active lead forearm rotation to increase clubhead speed (Dr Sasho Mackenzie research article)

10. The greater the fold (wrist cock) the more efficient the transfer of energy from the body to the club (Rod White).

11.  The trail arm to create more force in the downswing (Dave Tutelman - Leecommotion, the Right-Side Swing (tutelman.com) 

12. Wrist torque that retards or delays release usually winds up increasing clubhead speed at impact (Jorgensen)

Further, to create even more confusion there are research articles that:

a. Could not find a kinematic sequence proclaimed in point 4 above (Speed Generation in the Golf Swing - Brady C Anderson)

b. Could not find any energy being transferred between body segments in some proximal to distal sequence (Brady C Anderson). 

c. Some research says most of the work done by body segments is to move themselves, not get transferred between segments (Work and Power Analysis of the Golf Swing- Dr Steven Nesbit)

d.  Could not find any correlation between ground reaction forces and clubhead speed (Effect of Horizontal Ground Reaction Forces during the Golf Swing: Implications for the Development of Technical Solutions of Golf Swing Analysis :Maxime Bourgain, Christophe Sauret, Grégoire Prum, Laura Valdes-Tamayo, Olivier Rouillon, Patricia Thoreux, and Philippe Rouch).

Addendum: Athletic Motion Golf say that golfers should never try to hold lag, therefore contradicting the possible use of point 12  above.

I apologise to any forum members about posting so many articles that require some background in science to understand, but I thought I'd amalgamate most of the possible explanations in one thread rather than piecemeal over multiple threads.

Edited by Wildthing
added point 12 and 'Addendum'
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  • 2 weeks later...
Posted (edited)

Now this is an interesting video for creating clubhead speed by Eric Cogorno and might be worth a go on the range.

 

 

I think I understand some of the physics involved in the above video but that would involve the lead upper arm being 'connected' against the lead pec in the early downswing. This reminded me of Dave Tutelman's explanation of a way he was able to create more force transmission via the lead arm/hand to the club.

Leecommotion, the Right-Side Swing (tutelman.com)

Basically, he is demonstrating how he used his chest as a fulcrum to lever around the extended left arm.

radius_2.gif

 

I've seen an old video of Dave Tutelman's golf swing on you-tube and it definitely looks like he's doing the above. For those golfers who aren't spring chickens anymore and can't create a longer hand path to apply more 'work' (in the physics sense) to the club in the downswing , this could be a method to create more 'Force' along a shorter hand path (ie. for golfers who predominantly use their lead side to swing the golf club).

Here's a golfer who I suspect (I cannot be 100% certain) is levering his 'connected' upper arm by his chest .

 

 

However , I don't think Dr Sasho MacKenzie was doing the above in his one armed swing although he still struck it 250 yds. Logan Aldridge above can drive the ball over 300 yds.

Addendum 13/06/22:  On reflection, he might be using his pec to help lever his upper arm but not as efficiently as Logan. 

 

 

Edited by Wildthing
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Posted (edited)

Some more confusing aspects about generating clubhead speed have surfaced and I'm still having trouble understanding. It concerns 2 different research articles by Dr Sasho MacKenzie and I will post some comments later when I've read them again.

1. Basically, he found that most of the power a golfer generates in the golf swing (using a model) is via the shoulders , then wrists and then upper body torque.  That seems to infer that the fast twitch muscles (ie. in the shoulders) are generating most of the power in the golf swing but that doesn't confirm how much energy is being transferred to the club. It could be that most of the power is being used to move the shoulder girdle/arms and not the club. 

Addendum 13/06/22

I read the article again (extract below) and it does show how energy is transferred from the various segments in the model (from a proximal-distal direction). Although the torso is moving quite slowly, it was generating a significant amount of energy all through the downswing. 

Title Of Research Document Examining the delayed release in the golf swing using computer simulation (E. J. Sprigings and S. J. Mackenzie)

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

In the past, the main source of power for the golf swing had been attributed to the large muscles of the legs and torso (Cochran & Stobbs 1968). They had reasoned that a good golfer would be required to generate up to four horsepower (3040 W) to reach clubhead speeds in excess of 100 mph (44 m/s), and the only way of accomplishing this was to recruit approximately 13.6 kg of muscle mass, working flat out. They had neglected to take into consideration the role that the linear reaction forces at the joint centres play in transferring energy through to the clubhead via joint-force power (Fig. 8). Although muscle torques developed at the torso and shoulder are ultimately responsible for the linear reaction forces at the wrist joint, the peak magnitudes of muscle power never exceeded 800 W for any of the three joints. The highest maximum muscle power value (800 W) was recorded for the shoulder joint, with the next highest occurring at the wrist joint (600 W), and the smallest at the torso (390 W). The higher peak power value recorded for wrist torque when compared with the larger torso segment is a consequence of the force–velocity properties of muscle. The larger torso muscles are predominately composed of slow twitch fibres, while the muscles associated with wrist torque are known to have a higher ratio of fast twitch fibres (Johnson et al. 1973). This means that in the model the wrist torque generators had the capacity during the simulation to exert torque magnitudes in excess of 20 N m while the club was simultaneously reaching angular speeds approaching 30 rad. s), generating maximum power of approximately 600 W. On the other hand, the maximum torques developed by the torso segment (120 N m) were greater in magnitude than that at the wrist, but were exerted on the torso segment that was rotating relatively slowly (3.25 rad. s)  as impact approached, thus generating lower maximum power (390 W). Although the peak power provided by the torso was the lowest of the three segments, its contribution in terms of energy production was significant because of the magnitude of power being maintained near its peak for most of the downswing (Fig. 6). Inspection of Figs 9 and 10 reveal that energy leaves the distal end of the torso segment (Fig. 9, Emd1) and enters the proximal end of the arm segment (Fig. 10, Emp2). This is a result of the same shoulder muscle torque acting on both segments simultaneously, but in opposite directions. The same shoulder torque that helps to speed up the rotation of the arm segment slows down the rotation of the torso.

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

2. Then another improved 3D model produced an optimised clubhead swing using torque generators in the joints (within human capabilities) and produced the graph further below. One can see that in the early downswing there is virtually no shoulder torque and just torso generated torque.

Question: Torso is mainly slow-twitch muscles and generate smaller forces over a longer period of time compared to fast twitch muscles .  Therefore , why isn't the golfer model using the shoulder torques in the early downswing rather than the torso?  Is it because there are a greater number of slow twitch muscles in the torso where all the smaller forces add up and create on average a greater torque than all the combined fast twitch shoulder muscles?

MacK_3D.gif

 

MacK_degreesOfRotation.gif

 

MacK_torques.gif

 

 

 

Edited by Wildthing
read the research articles again and corrected my post
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Posted (edited)

Here's another piece of research from Dr Grober.

2006.11778.pdf (arxiv.org)

Now the maths is incredibly complicated so it's best to look at the summary. 

To explain it simply, it seems that many PGA Pro golfers have learned to apply a negative 'couple' on the club approaching impact to keep the clubhead path radius large so that there is less 'in-out-in' relative to the ball-target line.

Imagine what would happen if the clubface path was more curved 'in-out-in' if you just let the wrists flip the club through impact (see image below).

MiyahiraFlipperrThree.jpg

 

You would have to time the squaring of the clubface more perfectly than if the club-path was less curved (ie. longer radius). 

If the radius of the club path was longer, the clubface will not be rotating as much per unit distance of travel which might help in accuracy of strike with ball.

image.png.e5e4d2110485d60b87adcb685f2d0224.png

 

 

But a negative 'couple' applied via the hands on the grip will reduce the clubhead speed approaching impact, therefore it seems there could be a 'trade-off' going on between speed and accuracy.

So is this why we see many golfers with this post impact position (see images below) where the club has not bypassed the lead arm and the radius of the clubhead swing path being made longer for the sake of accuracy rather than clubhead speed?  There has not been enough proof gathered yet and we'll need to await for further research data.

RahmDHerTwo.jpg

 

ChampDHer.jpg

 

 

SpiethDHerFour.jpg

JohnsonDHer.jpg

And many more in this link below

Capture images of DHers (perfectgolfswingreview.net)

 

 

Edited by Wildthing
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Posted (edited)

Another interesting article I read was Dave Tutelman's  "Common myths debunked"

The link is below if you are interested (it's really worth a read so that you can identify possible flawed golf instruction).

Design Notes - Golf Physics p4 (tutelman.com)

A harder clubface gives more distance

On a full shot you want to hit the ball as hard as you can ... with both hands

Keep the club accelerating through impact for more power

The ball starts in the direction of the clubhead path and spins in the direction the clubface is pointing.

Hook/slice is caused by the clubface rotating closed/open during impact

Square grooves work because the sharp edges dig into the ball

Gear effect is caused by face bulge

The shaft is a string at impact. This one is true!

A draw rolls more than a fade because it has topspin

The ball goes farther at high altitude because of the thinner air

A good driver design has a high launch angle and low spin

 

The one that interested me the most was the below:

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

Hook/slice is caused by the clubface rotating closed/open during impact. Another recipe I've seen espoused for an intentional hook or slice. "Rotate the hands closed at impact for a hook; rotate them open for a slice."

My opinion is that these instructions may actually be effective for some golfers -- but not because the ball's spin is affected by the clubhead's rotation. It isn't! But the golfer focusing on rotating the face closed is likely to come into the ball with the face already closed. And that will produce a hook.

Another way to look at it is to see just how much rotation you can accomplish during impact. Numbers!!!
In a good swing, the wrists stay cocked until about 50 millisec before impact. So the club "lag" goes from 90° to 0° in 50 milliseconds. This is an average of 1.8° per millisecond.
Without even trying to rotate the club, the structure of the body rotates the clubface in synch with the uncocking wrists. So the clubface angle goes from 90° to 0° in 50 milliseconds.
Since impact lasts only 0.4 milliseconds, the clubface rotates 1.8° times 0.4 = 0.72°, during impact. That's less than three quarters of a degree.
It is very unlikely that deliberately rotating the club (with hands or forearms) will more than double the rotational speed at impact. But let's be generous and say that it could add another 3/4° of rotation at impact. How much hook do you think this tiny rotation will produce?
Basically, any value from this recipe has to do with the by-products of trying to rotate the club, and nothing to do with the actual rotation during impact.

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So in 50 msecs the clubface rotates 90 degrees, therefore rotation is averaging  90/50 = 1.8 degrees per millisecond.

0.4 msecs impact time means the club rotates  0.4 x 1.8 = 0.72 degrees during impact

If the forearms/arms doubled the increase in clubface rotation then that would be on average 2 x 1.8 = 3.6 degrees per millisecond

0.4 msecs impact time means the club rotates 0.4 x 3.6 = 1.44 degrees during impact.

Can these small differences in clubface rotation during impact period of 0.4 msecs actually make much difference to the accuracy of the strike?

If you did simple Trigonometry (see image below) comparing a 300 yard straight drive (ie. where clubface was square to ball-target line at point that clubface and ball lost contact)  versus one whose clubface rotated 1.44 degrees from square it would cause the ball to deviate approx 7.5 yards.

 

Ping cannot find any appreciable correlation between 'Rate Of Clubface Closure'  and 'Accuracy'. Seems that pro golfers might be experts in getting the clubface approximately square or close to square at impact whatever their ROC , but their ROC during the impact  period of 0.4 msecs doesn't affect their shot dispersion by any large amount (if you view 7.5 yds dispersion for a 300 yd drive as relatively small).

image.png.015417c896da4deff5ca39502ea28ed8.png


 

 

 

Edited by Wildthing
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Posted (edited)

Unsure whether I've posted this before, but I found this research article (link below).  So, to add to all the confusion, we have another scientific research article that claims that a bent lead elbow can create a dramatic increase in speed and greater accuracy (with less stress on the back).

WAS VARDON RIGHT

[PDF] Was Vardon Right | Semantic Scholar

According to the author/scientist he summarised his findings below:

 

3.2. The Vardon Swing. 
Let us turn now to the swing in which the elbow joint has a significant bend at the beginning of the down swing. Figure 3 shows the swing speeds obtained for various initial values of θ and a fixed initial wrist cock angle of 90 deg. as the initial elbow joint angle β(0) is increased from 0 to 105 deg. 

KY0S1SCRV0HP.png
Fig. 3. 


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.

FSWEVZ01MS7T.png

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 'Jorgensen, T.P. The Physics of Golf. 2nd Ed).  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). 
 

PS.

Here's a video where one of the TPI experts (Dave Phillips) advocate a bent lead arm.

 

 

Edited by Wildthing
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