Just had a lesson with Mike Adams, Top 5 golf instructor

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WILDTHING

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Thanks for the added video link! Anyone else with video or website info links please share, I’m trying to get as much information as I can. During my testing I seem to be a Rear post, Side-cover or cover R hand grip, for ground reaction forces I believe i’m primarily a glider (horizontal force), and somewhat of a launcher (vertical force). If anyone knows your pros that have a similar profile let me know, I’d like to watch slow motion swings. Thanks all!
Remember that 'Gliding' and 'breaking' is only a small power source and normally 'peaks' during transition or just very early in the downswing . The 'spinner' type of peak power source happens from P4-P5 , while the vertical 'peak' happens from P5-P6.

The gliding, spinning and launching has to happen in sequence (ie. the kinetic sequence) and not too late in the downswing. If you try and glide/spin/launch too late in the downswing there is not enough time left for its effect to reach the hands and apply the forces needed to create clubhead speed before impact.


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WILDTHING

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After seeing the you-tube and vimeo videos , I think I can make a decision regarding my future swing mechanics which might be best for my aging body.

For me personally , my backswing is restricted because of my lack of flexibility and I cannot jump/launch very well because my knees are becoming weaker every year. My forearm is longer than my upper arm therefore I have a more upright backswing plane and because I'm a 'side-cover' my downswing plane will probably be between my torso and shoulder plane. I'm more a rear-centre anchor/post with not as much pressure weight shift to my trail leg as a rear post and not much glide. I also find it very difficult to do right lateral flexion and do not wish to risk injury attempting it.

So it seems my best power source would be to utilise the spin torque aspect but how can I do that? The peaking of spin torque must happen between left arm 45 degrees from vertical (ie. P4.5) to left arm horizontal (P5) in the downswing (according to Dr Lynn's kinetic sequence concept) but I can just about get to P3 position (left arm horizontal) in my backswing. And even if I was able to get my left arm higher in the backswing , using more 'spin torque' (in my steeper downswing plane) would cause an OTT movement. Would this mean me having to factor in my faster OTT downswing by aligning my stance further to the right of target if I want extra clubhead speed while wishing to hit the ball straight (a functional pull)?

Anyhow , the fact that I cannot get further than P3 in the backswing and cannot use 'glide/spin/launch' power sources very effectively probably means I need to use an arm swing.

I'll need to revisit the Leslie King swing concept (again) and just use an arm swing with adequate wrist cock in the downswing to time the peak clubhead speed near impact. Goodbye to my Shawn Clement 'launch' powered type swing as its obvious that I will be unable to continue with that type of technique going forwards (but I'll keep doing the external focus cues).
 

WILDTHING

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Here is what Dr Scott Lynn said in reply to my email

My email:
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Dear Dr Lynn

I was watching your video on you tube

Winter Education: Ground Reaction Forces on Swing Catalyst with Dr. Scott Lynn - YouTube

But I was wondering if there were any more detailed articles showing how 'targetwards and braking' horizontal forces can somehow contribute into creating 'forces/torques' via the hands on the grip to increase the clubs angular velocity?

Further , I was also wondering how increased pelvic rotational acceleration (indicated by the increased torque ground reaction forces) can somehow contribute into creating 'forces/torques' via the hands to increase the clubs angular velocity?

However, I can understand how vertical ground reaction forces (if timed correctly) might influence the 'Net In Plane Force' applied to the club to increase 'In Plane MOF' and the clubs angular velocity (as per Dr Sasho MacKenzie's videos below). I can imagine that the more curved path of the left shoulder socket (influenced by the vertical forces) can have an effect on the magnitude and direction of the 'Net In Plane Force' and the 'In Plane MOF' .

Intro to Club Kinetics on Vimeo

In-Plane Couple and Moment of Force During the Golf Swing on Vimeo

Hopefully , you can point me in the correct direction.

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reply from Dr Lynn:
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Here is Dr Lynn's 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.

1624282389181.png

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

Lots to learn going forward, but I really appreciate your inquisitiveness and you reaching out with your questions. Let me know your thoughts on this.
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My reply:
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Dear Dr Lynn

Many thanks for your detailed reply and yes it does make sense. However I do have 2 issues that I'm trying to understand and I'll try and explain them below.

1st Issue:
I think horizontal glide forces might increase clubhead speed because of what I read on Dave Tutelmans website (although I haven't seen the physics/maths to prove it).

The chapter link is below :
www.tutelman.com/golf/swing/models2.php

I know this is a 'Double Pendulum' model but the physics of 'release' is still the same as the 'In Plane MOF' explained in Dr MacKenzie's vimeo videos. But what caught my interest was that Jorgensen's model allowed the fixed pivot of the DP to move laterally (ie. similar to the lateral movement of the left shoulder socket in a real golfers swing). Is it possible that 'horizontal/gliding' ground reaction forces might cause a real golfers lead shoulder socket to move in a similar way?

Note what Dave Tutelman said in the article:
"The forward shift provides almost 9% of the clubhead speed."

So it seems that even using a 'Double Pendulum' model the clubhead speed can be significantly increased by targetward lateral shift (without any vertical movement). I've asked Dave Tutelman whether he knows the physics to explain this (awaiting his reply).

2nd Issue (also from Dave Tutelman website)

www.tutelman.com/golf/design/physics3.php#timeConstant
He says the following:

"The time constant of the "plucked driver assembly" is about 40 milliseconds. That's almost 100 times longer than the contact between clubhead and ball. So anything that happens at the grip of the club during contact has no more chance of effecting the ball than if the club were being swung on a string."

I am assuming that any 'horizontal/torque/vertical' ground reaction forces would take time to have any influence on the forces delivered to the club via the hands . Also, more importantly, there will be a need for the hands to apply these forces at least 0.04 secs before impact to have any effect on the clubhead.

When I look at Dr MacKenzies "In-Plane Couple and Moment of Force During the Golf Swing" video , the club is around P6 about 0.042 secs before impact , therefore I suspect the peak grfs must be applied very early during 'transition/early downswing' to transmit themselves via the body to the hands/grip. So just wondering whether this is a realistic timeframe but I suppose we will never know without more research.

Anyhow, best wishes with your work with Mike Adams /Terry Rowles (and others) and look forward to their new book that is going to be published.

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I still had problems understanding how a 'lateral ' sway could increase clubhead speed so I bought Theodore Jorgensen's book 'The Physics Of Golf' and found the answer in his topic titled 'Five Experiments'.

I have summarised this in the image below but unfortunately this will be difficult to understand unless you have some background in physics.

1624282644729.png
 
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WILDTHING

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Here is Kyle Berkshire using some horizontal ground reaction forces but note what Dr Lynn said in the video, that many of the strikes go out of bounds in these long drive golfers. So maximising ground reaction forces and utilising them in sequence might help you swing faster but won't guarantee accuracy.

 

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