|
Post by imperfectgolfer on Apr 20, 2020 10:04:42 GMT -5
Here's a recent video with Sasho MacKenzie and Chris Como . I found what he said at 3:08 quite surprising where he mentions at P6 a golfer is 'not strong enough' to perform 60 degrees of forearm supination in .04 secs (I am assuming he means with a neutral grip). So he is reinforcing his concept of using a passive torque (by having the clubshaft below his hand path by P5.5) to help square the clubface. And he implies earlier in the video from 0:31 that even though Adam Scott swings 'On Plane' he is 'guessing' (because he swings hard left through impact) that Adam Scott is actually applying dynamic forces through the butt end to still create that same 'passive torque' effect. So I am assuming that if Adam Scotts hand path is not steeper than the clubshaft plane , he can still apply this passive torque force effect (even though it is invisible to the naked eye). The 2nd half of the video implies that the downswing is limited unless there is an upward net ground force vector (ie. left foot force greater than right) ahead of the COM. I am assuming he is also implying that the COP must move more to the left before the downswing can commence . Then he reinforces his 2nd concept (regarding increasing clubhead speed) where the golfer must exert a high upward ground force through his left foot while shaft vertical in the downswing. Chris Como did demonstrate that a targetwards slide of both upper and lower COM (such that net GRF force is directed through the COM) will limit the downswing (ie. not get angular momentum into the body) . I still find this concept of moving the COP rapidly to the left foot confusing unless they are somehow working out what actual net forces are being applied through each foot (using the area of contact with the ground). But he does say that the COP is a "measure of the average spot that the vertical force is coming out of the ground" . DG PS. If I'm not mistaken Adam Scott shifts plane from TSP to elbow plane and shallowing the club with a right upper arm adduction and pitch elbow move. So is SMK surmising that AS's left arm is applying a steeper downwards force to the grip of the club (than his clubshaft plane) while the right hand is preventing a 'toppling over' effect on the clubshaft (ie. an OTT)? That there are 2 torques cancelling each other out as the clubshaft plane shallows out (while still 'On Plane') with a build up in the magnitude of those equal and opposite torques up to P6? Then during PA#3 release, the right hand torque is relaxed allowing the 'ready-made built up' left hand supinatory torque to suddenly take over to apply the necessary 'squaring clubface' impetus by impact? I can only conclude that SMK is surmising that there is a build of potential torsional energy (like a torsional spring- see below explanation) in the left arm that can quickly be turned to KE later in the downswing. ---------------------- Energy StorageTorsion springs store energy by twisting about their axes. The energy stored in the torsion spring, as with any spring, is potential energy. This potential energy differs from kinetic energy because is has the potential to do work, but is not doing work at the time. Kinetic energy is simply energy that is doing work. It is stored by increasing the tension of the spring, which just means making it tighter. The tightness of the spring is directly proportional to the amount of energy stored in the spring. To release the energy, tension must be let off the spring, at which time it quickly reverts to its original position. This means that the spring unwinds to the position in which is has the least potential energy and in which there is the least possible tension on the spring. The kinetic energy is released by the pressure the spring exerts on the object to which it is attached. --------------------- I suspect one can see/feel this 'effect' in action if you generated a lot of twisting supinatory effort on your left forearm (with a clenched fist) but was preventing that supination by grabbing the left fist with your right hand . Now increase both the left forearm twisting force and the right hand 'restraining twist ' and you can feel the increased torsional strain in your left forearm . Then just relax your right hand grip and you will see a rapid supinatory rotation of the left forearm. If you attempted to rotate your left forearm by the same amount (as quickly as possible) just using the muscles of your left forearm (ie. no right hand involved) , the rate of supination seems much smaller. I'm finding the above explanation ,if that is what SMK is implying (and I'm probably wrong), very difficult to comprehend in a real golfers swing because it creates so much tension in the forearms and wrists that I cannot imagine it will allow an efficient release of PA#2. With regards SMK's correlation findings between GRF under left foot while clubshaft vertical , I think that could be too simplistic without understanding other variables that might be involved. There could be another biomechanical factor like the creation of the straighter hand path from P4-P5.5 that might also necessitate a larger GRF force in the left foot to elevate the left shoulder socket and secondarily cause a more acute 'change' in the hand path direction to increase clubhead speed so that both hands/clubhead are in the optimal position at impact for the golfers desired angle of attack. Imho, there does seem to be too many variables in the golf swing to 100% confirm cause and effect on the 'kinetic' side of biomechanical research. DG, I don't know why you have introduced this video in this "re-centering" thread because your questions relate to a totally different issue, which has been fully covered in previous threads. Because we have discussed these issues in depth previously, I will only make brief comments. You wrote-: " -- found what he said at 3:08 quite surprising where he mentions at P6 a golfer is 'not strong enough' to perform 60 degrees of forearm supination in .04 secs." I reject SMK"s "belief" that it requires a lot of muscular torque to release PA#3. Kevin Ryan's modified double pendulum model shows that it is possible for the clubface to square without adding any muscular torque - via the RYKE effect. If the left forearm is very relaxed, then it should require very little torque to release PA#3. Increased forearm muscle tension will radically increase the difficulty of releasing PA#3 without a lot of additional muscular torque. Having the right arm/hand applying a "restraining" torque (negative torque) is very harmful and the right forearm should be applying a positive torque to synergistically assist in the release of PA#3. I think that SMK is totally wrong to claim that Adam Scott's clubshaft is on the same plane as the force transmitted via the hands onto the club handle as it is moving down the hand arc path.
Jeff.
|
|
|
Post by dubiousgolfer on Apr 20, 2020 18:58:43 GMT -5
Dr Mann
I thought the Chris Como 're-centering slide' section of the video was relevant from a 'kinetics' perspective because it shows that while the golfer is re-centering (whatever method he uses) he must try to keep his COP ahead of his COM to generate angular momentum in his body after P4.
Yes apologies, we did discuss these other issues before so not worth resurrecting on this thread, although I'm surprised you still believe in the validity of the Ryke effect.
DG
|
|
|
Post by utahgolfer on Apr 20, 2020 22:02:13 GMT -5
Jeff, I appreciate the reference lines drawn on the back side of JS, but I think you should also show him at p1-9 with a vertical reference line drawn at p1 from the ground up between his bum cheeks and up over his head, and do the same for p2-9 with the reference line staying constant. That way we can see how he shifts his swing center across his entire swing and not just from p3 to p4.2.
UG
|
|
|
Post by dubiousgolfer on Apr 20, 2020 23:03:13 GMT -5
Hi UG
JS's pelvic trace is shown on this Gears video. Check out the little white dot movement on the pelvic trace (squiggly white line) but you'll need to enlarge it to full screen to get a better view.
DG
|
|
|
Post by imperfectgolfer on Apr 20, 2020 23:12:59 GMT -5
Dr Mann
I thought the Chris Como 're-centering slide' section of the video was relevant from a 'kinetics' perspective because it shows that while the golfer is re-centering (whatever method he uses) he must try to keep his COP ahead of his COM to generate angular momentum in his body after P4.
Yes apologies, we did discuss these other issues before so not worth resurrecting on this thread, although I'm surprised you still believe in the validity of the Ryke effect. DG I am not sympathetic to the "idea" (derived from Dr. Kwon) that angular momentum of the torso is solely derived from vertical GRM's created in the frontal plane. I strongly believe that a major source of the power to rotate the pelvis and upper torso counterclockwise during the downswing is derived from the muscular contraction of pelvic girdle muscles to rotate the pelvis and core abdominal muscles to rotate the upper torso.
If you do not believe in the validity of the RYKE effect, try and simply swing the club from P4 to P7.5+ without making any conscious attempt to utilize any forearm muscles to rotate the clubshaft counterclockwise around its longitudinal axis during the late downswing. Allow your left forearm to be very relaxed during the sequential release of PA#4 => PA#2. Are you not able to square the clubface by impact - even in the absence of any deliberate forearm muscular torque being applied prior to the release of PA#3?
Do you believe that Phil Mickelson is using significant forearm muscular torque to release PA#3 in his driver swing action - as shown below?
Note that PM's clubface is still open at P6.7 (image 2) and that it closes by impact - considering the fact that the MOI is very low when the clubshaft has nearly caught up to his lead arm by P6.7.
Jeff.
|
|
|
Post by imperfectgolfer on Apr 21, 2020 9:52:58 GMT -5
Hi UG JS's pelvic trace is shown on this Gears video. Check out the little white dot movement on the pelvic trace (squiggly white line) but you'll need to enlarge it to full screen to get a better view. DG DG, What am I supposed to learn from watching that white dot's movement? Interestingly, I decided to produce capture images of the GEARS overhead images to see if it could identify a pelvis/upper torso re-centering phenomenon in Jamie's late backswing that is not detectable using swing video capture images. Here are the capture images. Image 1 is at P3.5, image 2 is at P3.8, image 3 is at P4 and image 4 is at P4.2. I have drawn a blue line alongside the left side of his left buttocks area (hip joint area) and a red line in front of his upper torso at the level of the upper swing center at the P3.5 position. Note that there is no evidence of any re-centering phenomenon (leftwards shift) of either the pelvis or upper torso between P3.5 and P4. A small leftwards shift of the pelvis and upper torso is seen at P4.2 when Jamie is rotating his pelvis and upper torso counterclockwise. Jeff.
|
|
|
Post by dubiousgolfer on Apr 21, 2020 11:03:59 GMT -5
Dr Mann
If you look at 0:31 on that video , the white dot (which I assume is the loci of the centre of the pelvis) has not shifted left by any significant amount before the top of the backswing (so no re-centering move of pelvis before P4).
DG
PS. You said "I am not sympathetic to the "idea" (derived from Dr. Kwon) that angular momentum of the torso is solely derived from vertical GRM's created in the frontal plane. I strongly believe that a major source of the power to rotate the pelvis and upper torso counterclockwise during the downswing is derived from the muscular contraction of pelvic girdle muscles to rotate the pelvis and core abdominal muscles to rotate the upper torso."
I agree with you Dr Mann . I've read an article that says "The primary mechanism to actively regulate angular momentum is muscle force generation, which accelerates the body segments and generates ground reaction forces that alter angular momentum about the body’s center-of-mass to restore and maintain dynamic balance."
So the COP being front of the COM is not a generator of angular momentum but more of an identifier to show where average net vertical GRF pressure forces (and its moments of force about the COM) are acting to restore and maintain dynamic balance.
|
|
|
Post by imperfectgolfer on Apr 22, 2020 9:42:31 GMT -5
DG,
You wrote-: "I've read an article that says "The primary mechanism to actively regulate angular momentum is muscle force generation, which accelerates the body segments and generates ground reaction forces that alter angular momentum about the body’s center-of-mass to restore and maintain dynamic balance."
So the COP being front of the COM is not a generator of angular momentum but more of an identifier to show where average net vertical GRF pressure forces (and its moments of force about the COM) are acting to restore and maintain dynamic balance."
It makes no sense to me to state that the GRF's produced as a result of muscular action are only used to alter angular momentum and maintain dynamic balance or to state that the "COP being in front of the COM" is only an identifier of where the GRFs are working to maintain balance". Where is the "evidence" to support that "belief"? I think that it is as irrational as Dr. Kwon stating that angular momentum in the frontal plane is produced by vertical GRM's and that muscular action is only used to alter angular momentum among different body parts and to maintain balance. These two opinions are polar opposite opinions and I think that they do not help us to explain "reality" which is much more complex. Although I am personally more sympathetic to biomechanical explanations than explanations based on physics when it comes to explaining the golf swing - because a golfer is biomechanical machine and not a physical (inanimate) machine (like an Iron Byron machine); I think that it is irrational to then arbitrarily assign a purpose to the pattern of GRF-generation as only being used to maintain balance. I think that angular momentum of the torso is generated partly due to GRFs and partly due to muscular actions. For example, I believe that the counterclockwise rotation of the pelvis happening between P4 and P5 is partly due to contraction of the right-sided lateral pelvic rotator muscles and partly due to a horizontal GRF generated by pressing down into the ground under the left foot in a direction that is away from the ball-target line, and that different pro golfers use these "forces" in different (unknown) proportions.
Jeff.
|
|
|
Post by imperfectgolfer on Apr 22, 2020 12:20:10 GMT -5
Here is birds-eye view swing video of three famous pro golfers - Jack Nicklaus, Arnold Palmer and Gary Player - in their prime. I analysed that video to see if those 3 golfers used a distinct re-centering motion of either their pelvis or upper torso during their late backswing - before they started to rotate their pelvis counterclockwise.
Here are capture images.
Jack Nicklaus
When JN was a teenager, he used a rightwards pelvic loading pattern and an upper torso loading pattern that is intermediate between being rightwards-centralised or frankly rightwards.
In this later stage of his career, he is using a leftwards-centralised pelvic loading pattern and an upper torso loading pattern that is intermediate between being rightwards-centralised and vertical centralised.
Image 1 is at P3.75, image 2 is at P4, and image 3 is at P4.1.
I have drawn red lines alongside the outer border of his left buttocks and a blue line at the approximate position of his upper swing center (sternal notch area) when he was at P3.75.
Note that JN starts his pelvic rotation just before/at P4 while his shoulders are still rotating counterclockwise. I can see no definite lateral sway motion of either his pelvis or upper torso in a targetwards direction between P3.75 => P4. His upper swing center has moved slightly targetwards between P3.75 and P4, but I think that it is due to continued rotation of the upper torso, and not due to an upper torso re-centering sway motion. At P4.1, his pelvis has shifted left-laterally while his pelvis is rotating counterclockwise, but note that his upper swing center does not move much.
Gary Player
Image 1 is at P3.8, image 2 is at P4 and image 3 is at P4.1.
Note that he uses a leftwards-centralised pelvic loading pattern and a vertical-centralised upper torso loading pattern.
I have drawn red lines alongside the outer border of his left buttocks and a blue line at the approximate position of his upper swing center (sternal notch area) when he was at P3.8.
Note that there is no targetwards (re-centering) sway motion of his pelvis or upper torso happening between P3.8 and P4.
Note that he starts his pelvic hip-squaring motion at P4, and that he has a very small amount of targetwards shift of his pelvis happening at the same time.
Arnold Palmer
Note that he uses a leftwards-centralised pelvic loading pattern and a vertical-centralised upper torso loading pattern.
Image 1 is at P3.75, image 2 is at P3.9, image 3 is at P4 and image 4 is at P4.05.
I have drawn red lines alongside the outer border of his left buttocks and a blue line at the approximate position of his upper swing center (sternal notch area) when he was at P3.75.
Note that his pelvis does not shift targetwards between P3.75 and P3.9 although his upper swing center has moved targetwards due to the continued rotation of his upper torso.
Note that he starts to shift his pelvis targetwards just before P4 as he starts his squat move and counterclockwise pelvic rotation. Note that his hands move targetwards-and-upwards between P3.9 => P4 but his upper torso has stopped rotating clockwise. One could label this very small pelvic shift a re-centering move, but there is no re-centering move of his upper torso between P3.75 => P4 that cannot be explained by noting the continued clockwise rotation of his upper torso.
Jeff.
|
|
|
Post by imperfectgolfer on Apr 23, 2020 13:11:24 GMT -5
Here is another AMG-video on the re-centering move. Watch the video starting at the 10:15 minute time point showing the torso motion of two pro golfers as reproduced by the GEARS system. Here are capture images of the two pro golfers. Address
I have drawn a red line along the length of their lumbar spine. Note that their lumbar spine is vertical at address, rather than having a small degree of rightwards-tilt. P2 position I have drawn red lines along their lumbar and thoracic spines.
Note that the golfer on the right acquires a distinctly leftwards tilt of his thoracic spine.
P3 position. I have drawn red lines along their lumbar and thoracic spines. Note that both golfers acquire a marked tilt of both their lumbar and thoracic spines to the left - which presumably represents the "re-centering move" that the AMG instructors recommend. Most interestingly, both of those pro golfers do not seem to rotate their pelvis clockwise between P1 and P3. That's bizarre and not my idea of a biomechanically sound backswing action. Look at Gary Player, Arnold Palmer, and Jack Nicklaus in this video. Here are capture images of those 3 pro golfers showing how they look at P3 - where I have drawn a red line over their lumbar spine. Gary Player
Arnold Palmer Jack Nicklaus Note that all 3 of those pro golfers have lot of clockwise pelvic rotation that orientates the lumbar spine to the right.
I think that it's biomechanically sub-optimum to have the lumbar spine tilted to the left during the backswing action. What do you think?
Here is a slow motion swing video of Cameron Champ. Watch the video between the 1:00-1:15 minute time point to view the motion of his lumbar/thoracic spine between P1 => P4. Here are capture images. Image 1 is at P1, image 2 is at P2, image 3 is at P3 and image 4 is at P3.5. I have drawn red lines along his lumbar and thoracic spine (when visible). Note that his lumbar spine is always tilted to the right and note that his upper torso does not lean leftwards. I don't know who those two pro golfers are in the AMG-video, but I do not like their pattern of lumbar/thoracic spine motion during their backswing action - compared to the pro golfers that I have featured. As a side-issue, here are capture images of those two pro golfers at their P5.5 position. Look at how far their right elbow is positioned away from the right side of their torso at P5.5! I wonder whether they cannot efficiently perform an "active right arm adduction maneuver combined with a pitch elbow motion of the right elbow" because their upper torso is so tilted to the left at the start of their downswing.
Jeff.
|
|
|
Post by utahgolfer on Apr 25, 2020 1:38:38 GMT -5
Jeff, you are correct as I've seen over and over again. There is a nuance here, though, that is important.
I also agree that the gears system is limited in its utility and the pros which AMG illustrate seem unique and not exactly common.
The nuance is that a slight move off the ball to p3.5, and a slight forward motion back to center around p4 is certainly acceptable. This can easily be done with a rightward leaning spine. Center doesn't mean it has to be vertical. Center can be rightwards, too. It can be where ever the address position starts from. And, the movement can be very small and hardly noticeable.
The idea is to keep the swing dynamic and avoid a p4 position with too much momentum moving away from the target, or a p4 position that is too static with too much stop and go.
It is not much different than a pre-swing waggle or forward press, that gets the swing started and adds some minimal dynamic motion.
To move slightly off the ball is also dynamic and sets the backswing pivot. Similarly, to move slightly back or targetward is dynamic and begins to set the downswing pivot. And, after this slight targetward motion, the pelvis/hips can immediately rotate to begin the kinematic sequence. There is no need for any continued targetward slide of the body.
Consequently, there is no required reverse pivot, no required centralized pivot (unless the player starts with this), and it can certainly be done with a rightwards leaning spine.
It can be simple and straightforward and subtle.
The AMG instructors may try to make this into a bigger deal than it really is. I'm not sure. I just know this slight dynamic motion may help some players improve their swing transition motion. I also believe that many players can swing just fine without this slight additional motion.
This slight motion certainly does not violate any set in stone essential swing mechanics, imho.
UG
|
|
|
Post by utahgolfer on Jun 3, 2020 23:36:46 GMT -5
Here is a bird's eye view of JB Holmes swing starting at 0:37 s. There is a lateral rearward shift of his body/head from p1 to p3.9, a lateral targetward shift of his body/head back to where it was at address from p3.9 to p4, and this is maintained until about p5.5 where it again moves rearward several inches until after impact. Then, the body/head shifts targetward until it is over the lead foot to finish the swing.
And, each lateral movement of the body/head has a purpose: the first lateral rearward shift helps to promote backswing depth and body rotation; the second lateral targetward shift helps to provide a centered foundation from which begin and power the downswing; the third rearward lateral shift promotes right lateral bend so the player doesn't run out of right arm and leads to an elevated left shoulder that helps to decelerate the left arm into impact; and the fourth lateral targetward shift of the body/head promotes a way to release the momentum of the swing and finish the swing.
JB clearly follows a four step movement of his body/head from p1 to p10.
UG
|
|
|
Post by dubiousgolfer on Jun 4, 2020 7:48:27 GMT -5
Hi Dr Mann/UG
Maybe this JB idiosyncratic move is related to his ability to create clubhead speed by impact.
1. The lateral shift to his right is to prepare him to use a greater targetwards motion of his left shoulder socket to then generate a larger vertical MOF component on the clubs COM to release PA#4 2. The thoracic forward bend of JB will help his arms/club move on a more steeper backswing plane to facilitate point 1 and the creation of extra clubhead speed from P4-P5 (assisted by right arm adduction/pitch elbow move).
DG
|
|
|
Post by dubiousgolfer on Sept 3, 2020 6:41:51 GMT -5
Unsure whether we've seen this AMG video before , but quite interesting to visually see how the pelvis moves for pro golfers (09:40 - 10:38).
DG
PS. Doesn't this suggest that a root cause for early extension is in the backswing and allowing the centre of the pelvis to move towards the ball-target line? So how does one biomechanically stop the centre of the pelvis moving towards the ball-target line as the backswing progresses from address?
Doesn't that mean having to move the whole pelvis away from the ball-target line as it also rotates and pressure loads the right hip? And won't that also mean using more right hip flexion which will cause the head to drop as the golfer reaches P4?
I suspect the extent of hip flexion would depend on the golfers pelvic-torso (hula hula ) separation flexibility because I can't see Rory McIlroy's head dropping in the backswing.
|
|
|
Post by imperfectgolfer on Sept 3, 2020 9:30:25 GMT -5
Excellent video with beautiful visual graphics.
I agree with AMG that one should have more knee flex at address so that the pelvis is better centered (from back-to-front) at P1. It is also useful to think of slightly increasing one's degree of hip joint flex during the backswing and maintaining anterior pelvic tilt. If one "stands up" and acquires more posterior pelvic tilt during the backswing, then it will be more difficult to perform the downswing's rotary pelvic motion like those pro golfers (which necessitates a lot of hula hula flexibility).
Jeff.
|
|