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Post by dubiousgolfer on Jun 13, 2021 17:41:29 GMT -5
Here is an example where you don't need ground reaction forces to rotate (see 5:50-6:02)
But obviously ground forces do help facilitate some intended movement (steering the movement of the COM makes sense). So does swinging in some theoretically optimal manner create optimal ground reaction force patterns and does it work the other way around? Does the creation of some theoretical optimal ground reaction force patterns means you are swinging a golf club in an optimal manner?
DG
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Post by imperfectgolfer on Jun 13, 2021 19:17:31 GMT -5
UG, You stated-: " The outcome science can only be based on that. Does their method speed up overall progress and lead to lower scores? Nothing else matters. Sasho’s graph and correlation has little to do with this. If a given player hits the ball farther with a loaded lead foot at shaft vertical, then that’s all that matters. If he or she doesn’t, then it doesn’t matter. We only continue with what works. It’s an individual player endeavor, not how data points scatter on a graph. Same with the kinetic sequence. We go with what works. If a player does better with a vertical, horizontal, rotational kinetic sequence, then we accept it and continue on. It doesn’t matter what works for anyone else. We just use all we know to help that person. Success is based on improving path, face, and speed." I agree with you that an individual golfer should find what works for him in terms of him being able to consistently improve his clubhead speed, clubhead path and clubface control. However, I cannot understand how the MA/TR screening tests - i) trail grip testing and ii) post testing helps a golfer to achieve that goal. For example, the trail grip test only tests what is naturally comfortable when performing a right elbow folding mechanism. So, for example, if a golfer tests positive for an "on top" trail grip pattern using that trail elbow folding test it does not necessarily mean that it is the best trail arm delivery method for that individual golfer. It also depends on other biomechanical factors eg. spinal flexibility, biomechanical capacity to perform dynamic torso-pelvic separation in the early-mid downswing, biomechanical capacity to perform right lateral bend, biomechanical capacity and inclination to perform a rotary pelvic motion from a rear-post position using the right-sided lateral pelvic rotator muscles versus a capacity and inclination to perform a launcher pelvic motion from a front-post position. I have never seen MA/TR perform a detailed analysis of a golfer's capacity to perform a complete pivot motion by assessing their spinal flexibility in a detailed manner. MA stated that you are better off being what you are rather than being something else. However, how can very simplified tests (trail grip testing and posting test using a club placed across the thighs) really determine what is the best way for a golfer to move when actually performing a golf swing. Take my personal example, I test positive for being a front-post golfer and being an "on-top" golfer, but I cannot possibly produce an in-to-out clubhead path between P4 => P6 under those conditions because of my lack of spinal flexibility. I have a much better ability to hit the ball consistently straight if I use the combination of a rear-post position and an "under" right trail hand grip. Another example. Jordan Spieth uses a weak lead wrist and weak trail grip strength. TR stated that it would be a mistake for Jordan Spieth to use a side-on trail grip. Why? How could that very small change definitely (irrefutably) have a deleterious effect? Another example. TR describes a test to see how a golfer changes his golf swing motion when turning the clubface 20 degrees open, and 20 degrees closed, at address - when the ultimate goal is to hit the ball straight. These are the two patterns that emerge when TR performed that test in order to hit the ball straight.
Image 1 shows how TR swings when the clubface is closed 20 degrees at address (relative to the trail hand) and when he then tries to hit the ball straight. Note that he keeps his trail hand under the club handle to keep the clubface from being closed at impact. Image 2 shows how TR swings when the clubface is open 20 degrees at address (relative to the trail hand) and when he tries to hit the ball straight. Note that he rolls the trail hand over the lead hand by performing a trail forearm pronatory motion in his late downswing.
I personally believe that neither of those flipping-style golf swing actions are suitable for a golfer who uses a TGM swinging action, an intact LFFW/GFLW technique and who performs a DH-hand release action through impact.
You stated that you are impressed by Scott Lynn because his session 5 presentation was well done. Formal presentations can readily be well presented because they are prepared in advance, but the more important question is whether Scott Lynn can help a golfer perform the golf swing better. Do you think that Scott Lynn was helping Brendon Devore improve his golf swing action in the following videos?
Jeff.
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Post by imperfectgolfer on Jun 13, 2021 19:22:27 GMT -5
DG,
Your last two posts are in a mental stratosphere, which is a mental place that I never visit.
Jeff.
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Post by dubiousgolfer on Jun 13, 2021 20:43:20 GMT -5
For me personally , my backswing is restricted because of my lack of flexibility and I cannot jump 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 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 P5 (according to Dr Lynn's kinetic sequence concept) but I can just about get to P3 position 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.
DG
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Post by utahgolfer on Jun 14, 2021 15:20:50 GMT -5
Jeff, You stated-: "However, I cannot understand how the MA/TR screening tests - i) trail grip testing and ii) post testing helps a golfer to achieve that goal. For example, the trail grip test only tests what is naturally comfortable when performing a right elbow folding mechanism. So, for example, if a golfer tests positive for an "on top" trail grip pattern using that trail elbow folding test it does not necessarily mean that it is the best trail arm delivery method for that individual golfer. It also depends on other biomechanical factors eg. spinal flexibility, biomechanical capacity to perform dynamic torso-pelvic separation in the early-mid downswing, biomechanical capacity to perform right lateral bend, biomechanical capacity and inclination to perform a rotary pelvic motion from a rear-post position using the right-sided lateral pelvic rotator muscles versus a capacity and inclination to perform a launcher pelvic motion from a front-post position. I have never seen MA/TR perform a detailed analysis of a golfer's capacity to perform a complete pivot motion by assessing their spinal flexibility in a detailed manner. MA stated that you are better off being what you are rather than being something else. However, how can very simplified tests (trail grip testing and posting test using a club placed across the thighs) really determine what is the best way for a golfer to move when actually performing a golf swing. Take my personal example, I test positive for being a front-post golfer and being an "on-top" golfer, but I cannot possibly produce an in-to-out clubhead path between P4 => P6 under those conditions because of my lack of spinal flexibility. I have a much better ability to hit the ball consistently straight if I use the combination of a rear-post position and an "under" right trail hand grip. Another example. Jordan Spieth uses a weak lead wrist and weak trail grip strength. TR stated that it would be a mistake for Jordan Spieth to use a side-on trail grip. Why? How could that very small change definitely (irrefutably) have a deleterious effect?"
Response: The screening tests may or may not help to achieve a better path, face, and speed. The are simply a starting point. MA says "test, don't guess", but it's still a guess. No one knows, including MA and TR, if a given screen outcome will work until it is tested. If any "test-guess" doesn't lead to better results, it must be dropped and changed, and the search continues. That's why I say it's not helpful to critique the screens. They do not matter at all when it comes right down to it. They are simply one step above a pure guess. You could make them better (or less of a guess) or add new ones to improve the guessing process, but that's it. They are basic screens with no outcome value unless they happen to speed up the improvement process.
You stated: "I personally believe that neither of those flipping-style golf swing actions are suitable for a golfer who uses a TGM swinging action, an intact LFFW/GFLW technique and who performs a DH-hand release action through impact."
Response: I agree. The drive-hold release is logical and should work well for any player. But, our personal belief system doesn't matter if a player like Luke Donald actually plays better with a early flip release. He may have never tried a drive-hold release or been taught how to do it, and if this is the case, it is a mistake. If Luke hasn't tried every possible release option to see what works best for him, then he isn't following the MA and TR playbook. The only way to know is based on valid path, face, and speed data. My best guess is that Luke has tried it and he does better with what he currently uses (a flip release). It could be that he first learned to do it this way and his brain is hard-wired to flip through impact. Of course, this seems like a lame excuse on the surface, but it is a legitimate reason. Changing a release pattern that is imprinted on the brain may be much more difficult to change than we think. In addition, Luke may have specific body and swing characteristics that make a flip release better for him. For us to guess or preach otherwise, without more information and data, is only speculation.
You stated: "Take my personal example, I test positive for being a front-post golfer and being an "on-top" golfer, but I cannot possibly produce an in-to-out clubhead path between P4 => P6 under those conditions because of my lack of spinal flexibility. I have a much better ability to hit the ball consistently straight if I use the combination of a rear-post position and an "under" right trail hand grip."
Response: You might test for these preferences, but you would only stick with those that lead to your best path, face, and speed data. If your spinal restriction did not enable you to benefit from any or all of the screening hints, you would quickly move on and find out what does work the best. It is a work in progress from start to finish. Our initial swing screen hints or guess preferences are of no consequence in the end, unless they prove themselves beneficial. The first thing I would have you do is see if you can swing from a more bent-over torso position which might decrease your maximum back swing rotation ROM, but improve your spinal rotation function during the downswing. With your shoulders more pitched (rotating more like a Ferris wheel), it might help you solve part or all of your OTT issue you currently have with your present golf posture. But, ideally all would be done with simultaneous force plate, Trackman, and Swing catalyst data to guide any recommended grip, posture, or swing adjustments. You and I (and any golfer that matter) might think we have tried everything, but that is often not the case, especially within the guiding power of simultaneous force plate, Trackman, and Swing catalyst data.
You stated: "Do you think that Scott Lynn was helping Brendon Devore improve his golf swing action in the following videos?"
Response: It was good to watch those videos and, in my opinion, SL achieved his "lesson objective," which was to educate BD on the kinetic sequence, and to indicate which kinetic sequence could help BD increase his swing speed most effectively. From what I could see, BD was encouraged to get more speed from his rotational component via increasing left foot GRFs. BD did as instructed and increased his 7-iron speed from a high speed to an even higher speed. Could more be covered? Yes, but not in a 30-minute lesson. I'm still very impressed with SL's work.
BD did increase his speed during this time period (2 years ago), but then he moved on to path and face angle issues, which he continues to work on. However, BD did not work with MA, TR, or SL to fix his path and face issues, using simultaneous feedback from force plates, Trackman, video, etc., which I think is problematic. He has gone to an number of different instructors, which keeps him moving in many different directions. I'm not saying MA and TR have all the answers; I just think BD should have stuck with them longer to fully identify all possible preferences and match-ups. Then, he could have had gone to other teachers if he wanted to, since tweaking his golf swing appears to be his highest priority.
Also, DG, there isn't anything wrong with only swinging to p3 as the top of your back swing. Tony Finau and others do the same. From there, you have to determine if you can create enough horizontal, rotational, and vertical force to generate enough club head speed in the time allotted. If you can't, then yes will have to use more arm power (which is fine if this is your only source). However, most likely you can still maximize one of the three kinetic forces, apply it to the best of your ability, and increase your club head speed.
UG
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Post by imperfectgolfer on Jun 14, 2021 15:28:54 GMT -5
For me personally , my backswing is restricted because of my lack of flexibility and I cannot jump 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 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 P5 (according to Dr Lynn's kinetic sequence concept) but I can just about get to P3 position 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. DG I do not believe that an active pelvic's motion torque must happen at a prescribed time if one has a limited backswing arm motion that is less than 10 o'clock. I think that if you are a rear-center post golfer that you can use your right-sided lateral pelvic rotator muscles to produce the torque required to rotate the pelvis starting immediately at the transition to the downswing. The key phenomenon that must happen is that the pelvic motion must induce i) an immediate motion of the left shoulder socket that can immediately induce the release of PA#4 and ii) the lead arm has to move downplane in a non-OTT manner. I think that using an independent lead arm motion and a reactive pelvic motion is a sub-optimal secondary choice. Jeff.
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Post by dubiousgolfer on Jun 14, 2021 16:57:25 GMT -5
Dr Mann
What I am having trouble understanding is how horizontal and torque ground reaction forces can end up being a power source of clubhead speed (according to Scott Lynn's kinetic sequencing Horizontal/Torque/Vertical).
Has any of the videos explained:
1. How targetwards and braking horizontal ground reaction forces end up increasing clubhead speed? 2. How increasing the torque ground forces with increased pelvic rotational acceleration can influence the timing and contraction of the internal/external obliques (that rotate the ribcage in the downswing to release PA#4)? If a golfer has a large degree of pelvic/torso separability does that mean he/she will be mainly using 'Horizontal and Vertical' ground reaction forces to generate clubhead speed?
I thought that 3D data showed that LPGA players had on average quicker pelvic rotation than PGA players yet there was no correlation with increased clubhead speed? I'm assuming that all of this is factored in when tests are performed.
DG
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Post by imperfectgolfer on Jun 14, 2021 18:24:32 GMT -5
Dr Mann What I am having trouble understanding is how horizontal and torque ground reaction forces can end up being a power source of clubhead speed (according to Scott Lynn's kinetic sequencing Horizontal/Torque/Vertical). Has any of the videos explained: 1. How targetwards and braking horizontal ground reaction forces end up increasing clubhead speed? 2. How increasing the torque ground forces with increased pelvic rotational acceleration can influence the timing and contraction of the internal/external obliques (that rotate the ribcage in the downswing to release PA#4)? If a golfer has a large degree of pelvic/torso separability does that mean he/she will be mainly using 'Horizontal and Vertical' ground reaction forces to generate clubhead speed? I thought that 3D data showed that LPGA players had on average quicker pelvic rotation than PGA players yet there was no correlation with increased clubhead speed? I'm assuming that all of this is factored in when tests are performed. DG I think that trail foot horizontal GRFs (operating parallel to the ball-target line) are simply used to move the pelvis targetwards at the start of the downswing in golfers who are rear-post golfers. Then, the golfer will increase pelvic rotational speed via the generation of a pelvic rotary torque - either via dual horizontal GRFs operating in the AP direction (lead foot pushing towards the ball-target line and trail foot pushing away from the ball-target line) or via the use of the right-sided lateral pelvic rotator muscles. A faster pelvic rotational speed allows for a faster upper torso (lead shoulder) rotational speed and thereby a more potent release of PA#4. A braking force is used to prevent excessive pelvic sway and it happens when the a golfer generates a vertical GRF under the lead foot in the mid-downswing that allows for a negative horizontal GRF to be simultaneously generated that brakes the targetwards swaying motion of the pelvis. If the pelvis avoids swaying in the mid-late downswing and becomes stabilised by the braking force it probably allows the upper torso to rotate faster. Torso-pelvic separation varies in different golfers and it is unclear to me whether it really affects clubhead speed. I don't think that horizontal and vertical GRFs affect a golfer's degree of torso-pelvis separation and I think that it is a golfer-dependent variable of uncertain value. I agree that male PGA tour golfers can drive the ball further than LPGA tour golfers despite the fact that their pelvic rotational speed is less between P4 => P5.5. I strongly suspect that male golfers get their increased clubhead speed from i) stronger lats and arm muscles that allow for a faster downward component of the release of PA#4 and ii) an ability to retain clubhead lag for longer thereby increasing the speed of release of PA#2. However, my personal opinion has not apparently been verified by any study! Jeff.
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Post by dubiousgolfer on Jun 14, 2021 18:32:12 GMT -5
Many thanks Dr Mann DG PS. I found this on Dave Tutelman's website regarding Jorgensen's swing model where he adapted it to be able to move the central hub (to represent lateral movement of the left shoulder joint ). The lateral movement would be equivalent to a golfer using horizontal ground force reactions. He states the following: "The forward shift provides almost 9% of the clubhead speed" This is quite a significant portion of clubhead speed and one can see there is no upward movement (ie. equivalent to vertical grf) . I am unsure whether changes in the 'shoulder torque' has to be computed in during the mid-late downswing as 'lateral movement' stops/brakes . If it was computed in to rotate faster , then it might validate Dr Mann's previous post comment below. "If the pelvis avoids swaying in the mid-late downswing and becomes stabilised by the braking force it probably allows the upper torso to rotate faster."
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Post by imperfectgolfer on Jun 16, 2021 14:09:22 GMT -5
When watching the MA/TR webinar video sessions, I noted that they stated the following regarding an on-top golfer. 1) An on-top golfer (who, by definition, has a weak trail hand grip) must keep the trail elbow higher than the lead elbow throughout the swing (backswing and downswing). 2) An on-top golfer uses a punch elbow motion of the trail elbow between P4 => P6 that gets the trail elbow slightly behind the trail hip area at P6 (rear linkage). 3) The trail elbow does not bypass the trail hip area between P6 => P7 and slide across the front of the torso. 4) The trail arm straightens early in the later downswing and the straightening trail arm will cause the trail palm to rotate counterclockwise because the trail forearm tends to pronate when the trail arm reaches its end-range of trail arm straightening. 5) The trail hand will have the same orientation at impact as it had at address, and the trail palm will roll over the lead hand through impact - as seen in the following capture images of Patrick Reed's followthrough. Note that his trail elbow remains close to the right hip area at impact and note that his pelvis/upper torso are relatively square to the ball-target line. Note how his trail arm is fully straightened post-impact and note how his trail palm is rotating counterclockwise through impact so that it faces partially groundwards soon after impact - image 3.
However, all of those many listed features do not have to occur in a golfer who uses a weak trail hand grip (on-top trail hand position). Consider Patrick Rodgers golf swing action. Here are capture images of his address/impact trail hand alignments. Image 1 is at address. Note that he has an on-top trail hand position. Note that his lead hand grip is neutral. Image 2 is at impact. Note that his trail hand is less rotated counterclockwise at impact because his trail forearm is still supinated at impact - I have drawn a blue line down his trail antecubital fossa and a red line over his lower radial bone in his lower trail forearm and the red line is rotated more clockwise than the blue line. Here are capture images of his downswing. Image 1 is at his P4 position. Image 2 is at his P5 position - note that he uses a very active right arm adduction maneuver combined with a pitch elbow motion of his trail elbow that gets his trail elbow to be well below his lead elbow at P5. Image 3 is at his P6 position. Note that his pelvis already well open at P6 and his trail elbow is in front of his right hip area. Note that his trail palm is not facing the ground very much - because his trail forearm is very supinated at P6 (note that the red line is rotated clockwise relative to the blue line). Image 5 is at impact. Note that his trail elbow has moved across the front of his right hip area while his pelvis continues to rotate more open - that allows him to reach impact with a significantly bent trail arm and significantly bent trail wrist.
Note that his trial forearm remains supinated throughout his later downswing - it is supinated at P6.5 (image 4) and it is still supinated at impact (image 5). There is no evidence of a right forearm pronatory motion happening - as seen in Patrick Reed's late downswing. Here are capture images of his DH-hand release action. Image 1 is at P6.5, image 2 is at impact and image 3 is at P7.4. Note that his clubshaft has not bypassed his lead arm (from an angular rotational perspective) at P7.4 - which means that he is DHer. Note that his trail arm is still slightly bent at P7.4 and his right wrist is still slightly extended at P7.4. Note that his trail palm is partially facing skywards at P7.4 and it does not roll over to face the ground.
I think that Patrick Rodgers' golf swing action demonstrates that having an on-top trail hand position at address does not mean that one has to swing like an on-top golfer (as rigidly prescribed by MA/TR) and one has the option of i) performing an assertive rotary pelvic motion during the downswing (and not a launcher-style of pelvic motion); ii) assertively adducting the trail arm using a pitch elbow motion between P4 => P6 so that the trail elbow drops well below the lead elbow; iii) using a delayed trail arm straightening action combined with a trail forearm supinatory motion (which combined with a clockwise trail wrist circumductory roll motion) in the later downswing causes the trail palm to face more skywards between P6 => P7 (and even potentially further to P7.4 if the golfer uses a DH-hand release action). Jeff.
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Post by dubiousgolfer on Jun 16, 2021 16:23:16 GMT -5
Here is an exchange of emails I had with Dr Scott Lynn ------------------------------------------------------------------ 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. --------------------------- 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. 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. Scott K. Lynn, PhD Professor (Biomechanics) Department of Kinesiology California State University, Fullerton Phone (657)278-7779 ------------------------------------------------------ Here is my reply --------------- 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.phpI 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#timeConstantHe 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. DG
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Post by dubiousgolfer on Jun 16, 2021 19:03:06 GMT -5
Dr Mann
I'm afraid I don't understand what is meant by "trail elbow higher than the lead elbow throughout the swing (backswing and downswing)"
When I look at the DTL view of Patrick Reed's driver swing , I cannot see the trail elbow above the lead elbow (am I missing something?).
DG
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Post by imperfectgolfer on Jun 16, 2021 21:46:17 GMT -5
DG,
SL stated-: "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)."
That makes no sense to me. Doesn't the peak vertical and horizontal braking forces happen at around P5.5. Why should it affect the net force (which is mainly due to the MoF) that is happening at around P6.7 (in his diagram), which is much later in the downswing? Also, at that late stage of the release of PA#2, why should any additional force be needed to speed up the release of the club?
Jeff.
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Post by imperfectgolfer on Jun 16, 2021 22:06:27 GMT -5
Dr Mann I'm afraid I don't understand what is meant by "trail elbow higher than the lead elbow throughout the swing (backswing and downswing)" When I look at the DTL view of Patrick Reed's driver swing , I cannot see the trail elbow above the lead elbow (am I missing something?). DG I agree that PR's trail elbow is not higher than his lead elbow. Here is an example of a takeaway action where the trial elbow is higher than the lead elbow during the mid-backswing. Colin Montgomerie backswing action. Note that the trail elbow is higher than the lead elbow at P2 (image 2) and at P3 (image 3). Here is Patrick Rodgers takeaway Note that the trail elbow is marginally higher than the lead elbow in image 3.
I have never seen the trail elbow being higher than the lead elbow during the mid downswing. When performing a punch elbow motion, the elbows are usually at similar height at around P5 => P5.5. When performing a pitch elbow motion, the trail elbow is definitely lower than the lead elbow at P5. Here is Steve Marino's golf swing. Note that his trail elbow is higher than his lead elbow during most of his backswing action.
Here is Steve Marino's downswing. His trail elbow is higher than his lead elbow at P4 - because he has a flying right elbow. However, his elbows are at a similar height at P4.5 (image 2) and his trail elbow is lower than his lead elbow at P5.5 (image 3).
Jeff.
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Post by dubiousgolfer on Jun 17, 2021 8:30:44 GMT -5
Many thanks Dr Mann Maybe Dr Lynn's image was just an example to show how grfs could change the 'In Plane Net Force ' across the club and affect the MOF. I think all the grfs have to be peaked in some kinetic sequence before P6 is reached to allow enough time for their influence to permeate through the hands/grip. Then there must be additional time for those forces/torques applied at the grip to take effect on the clubhead before impact. Miura's article on 'Parametric Acceleration' seems to suggest that the pull forces acting normal to the 'hand path' in their model happens later maybe around P6.2-P6.4 and 0.04 secs before impact (which strangely enough is the same as the 'time constant' in Dave Tutelmans article which describes the time it takes for an action on the grip of a driver to take effect on the clubhead). I don't think MA/TR/SL have the full facts yet about how grfs affect the timing of the magnitude and direction of the 'In Plane Net Force' via the hands during the downswing. people.stfx.ca/smackenz/Courses/DirectedStudy/Articles/Miura%202001%20Parametric%20acceleration%20effect%20of%20inward%20pull.pdfDG
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