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Post by imperfectgolfer on Jul 10, 2024 12:12:30 GMT -5
Watch the following BeBetterGolf videos. Video 1: Video 2: The guest (Krill) is a person who has invented an instrumented grip that can measure grip pressure during the golf swing action. He admits that he has no background knowledge regarding golf swing mechanics/biomechanics, but that his accumulated grip pressure data on skilled pro golfers shows i) that the lead hand's grip pressure is greater than the trail hand's grip pressure during the downswing action and ii) that the lead hand's grip pressure increases between P4 => P5 in a pro golfer and that it reaches its peak pressure measurement at P5 and that it then decreases between P5 => P7+. Is this grip measurement result useful? I personally am not surprised by the grip measurement result because it is self-evident to me that it should happen in a skilled amateur/pro golfer who uses a pivot-induced TGM swinging action. Consider Rory McIlroy's downswing action? Image 1 is at P4, image 2 is at P5, image 3 is at P5.5, image 4 is at P6 and image 5 is at P6.5. I have drawn a yellow line down the club handle.
Note that the peripheral clubshaft bends backwards between P4 => P5? Why? The answer is obvious to me - it is because a linear pulling force is being applied by the lead hand with respect to the club handle when it is pulling the club handle down the hand arc path against the resistance of clubhead inertia (which is large at the start of the downswing when the club first starts to reverse direction). It is biomechanically natural/automatic for the human brain to reflexly/automatically instruct the lead hand to grip the club handle tighter/firmer during this early downswing phase between P4 => P5 and it does not require a conscious/deliberate choice. What is the biomechanical source of the lead hand pulling force in Rory's driver golf swing action? It is mainly due to the pivot motion initiated by the pelvis actively shift-rotating during the P4 => P5 time period. For example, if his pelvis is rotated 50 degrees clockwise at P4 and then square at P5, that means that the pelvis has rotated ~50 degrees counterclockwise during the P4 => P5 time period. If there is no additional independent upper torso rotation happening between P4 => P5, then that means that Rory's upper torso will rotate counterclockwise by ~50 degrees between P4 => P5 and that will cause his lead shoulder socket to move targetwards by many inches during that early downswing time period. That motion of the lead shoulder socket will pull the lead humeral head along and it will provide most of the "lead hand pulling force" that is transmitted via the lead arm, which is acting as a passive lever, to the lead hand. The lead shoulder girdle muscles also provide an additional lead hand pulling force if they are actively contracting between P4 => P5 and that is very likely in Rory's driver golf swing action where his hand arc path is steeply downwards between P4 => P5. Note that the peripheral clubshaft remains bent backwards between P5 => P5.5 due to the ongoing presence of the lead hand's pulling force with respect to the club handle. Rory's lead hand speed probably reaches its maximum speed at ~P5.5. However, the amount of lead hand pulling force that needs to be applied between P5 => P5.5 is obviously going to be less because the MOI of the clubhead is significantly reduced by P5 when the clubhead has already reached a significant degree of momentum by P5. Note that the peripheral clubshaft starts to bend forwards between P5.5 => P6.5 and that is due to the forces/torques causing the release of the club (release of PA#2). During that club release phase time period that mainly happens between ~P5.5 => P7, Rory's lead hand speed is slowing down by ~ 25% , so it could be traveling at 20mph at impact when it was traveling at 25mph at P5.5. It therefore makes sense that the lead hand's grip pressure will automatically/naturally decrease during the club release phase that happens between P5.5 => P7. Expressed differently, swing power is generated during the downswing by the sequential release of PA#4 (release of the lead arm) => PA#2 (release of the club) where the release of PA#4 mainly happens between P4 => P5.5 and where the club release phenomenon mainly happens between P5.5 => P7. It therefore makes sense that the lead hand's grip pressure will naturally decrease starting between P5 => P5.5 and continue to decrease between P5.5 => P7+. The human brain will naturally/automatically be sending less lead hand pulling/neurological instructions to the lead hand after P5/P5.5. A second biomechanical factor to consider is that the efficient release of PA#2 between P5.5 => P7 will stretch the lead forearm's muscles/tendons during the club release phase and make it far less likely that the finger flexor muscles are still actively flexing and thereby maximally squeezing the club handle. If the lead hand is still applying a very firm handle-squeezing force after P5.5 - as seen in Brendon Devore's golf swing action - then that means that he is not optimally performing an efficient pivot-induced TGM swinging action. The optimal solution is to improve his golf swing biomechanics that are casually responsible for the efficient sequential release of PA#4 => PA#2. By primarily focusing on the lead hand's grip pressure measurements Brendon will not necessarily be optimizing the forces/torques being applied by the lead hand on the club handle - unless he more efficiently improves the underlying biomechanics/mechanics required to optimize the sequential release of PA#4 => PA#2. Jeff.
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Post by imperfectgolfer on Jul 13, 2024 11:49:15 GMT -5
Further comments. Brendon stated in his BBG video that grip pressure measurements are likely going to be the next "big thing" in technology-based golf instruction following the path that happened with force plate measurements. I cannot understand the rationale for his claim. Why would a golf instructor/golfer want to measure how much a golfer is squeezing the grip during his downswing action? I can understand why one would want to use an instrumented grip (like the Koike instrumented grip) that could possibly measure the forces/torques being applied to the club's grip handle by the hands, but the Koike instrumented grip handle produces unreliable and undecipherable results - see this evaluation by David Tutleman at www.tutelman.com/golf/swing/openloop.phpBrendon tried in his BBG video to maximise his lead hand's grip pressure measurement at P5 and then allow it to gradually decrease between P5 => P7. However, he never succeeded despite multiple swing attempts. How can a golfer even attempt to decrease the lead hand's grip pressure measurement between P5 => P7 without deliberately altering the forces/torques that he is trying to apply to the club handle with his hands? Brendon never stated how he was going to alter the forces/torques being applied to his club handle by his lead hand during his downswing action and how they could possibly have any causal connection with any grip squeezing grip measurement? According to the inventor of the Sensoredge grip pressure measurement handle, Brendon was the first golfer who manifested a large increase in lead hand grip measurement post-impact (to >100%) and that this phenomenon does not happen in pro golfers. He could not provide an explanation for the phenomenon. One possible explanation is that Brendon is gripping the club handle very tightly with his lead hand soon after impact because he is trying to direct the motion of the club post-impact to move in an inside-left direction by using a pulling action of his lead arm/hand. Here is Viktor Hovland's clubhead path post-impact. Image 1 is at P7 and image 2 is at P7.5.
Note how his clubhead path moves inside-left between P7 => P7.4 due to the fact that his lead hand moves inside-left during that time period. Let's presume that VH does not manifest a large increase in lead hand grip pressure during that time period - how is that possible? I believe that it would be possible if the lead hand moved inside-left solely due to his super-efficient counterclockwise rotation of his pelvis/upper torso and where the angular velocity of his lead arm is perfectly matched relative to the angular velocity of his clubshaft during that time period. Because Brendon does not have the same efficient counterclockwise pivot motion as VH between P7 => P7.4, he could be using his lead arm/hand to independently direct his club handle in an inside-left direction. Jeff.
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Post by dubiousgolfer on Jul 13, 2024 15:14:36 GMT -5
I cannot understand how trying to replicate an elite golfers grip pressure traces by timing the squeezing of the fingers and other areas of the hand can influence the kinematics of a golf swing and the intended clubface/ball impact conditions.
DG
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Post by imperfectgolfer on Jul 17, 2024 10:58:04 GMT -5
Here is Brendon's latest BBG video on the topic of lead hand grip squeezing pressure. Brendon is again showing his serious lack of knowledge regarding golf swing biomechanics/mechanics by trying to claim that there is a condition of "singularity" at P5 between two facts - i) that a golfer is maximally squeezing the club handle with his lead hand at P5 and ii) that a golfer is maximizing the vertical GRF under his lead foot at P5. It may be true that some pro golfers may manifest that combination of facts, but many pro golfers may not manifest that pattern and there is also no necessary causal connection between those two facts that makes it rational to claim that a condition of "singularity" exists. Take the fact that certain pro golfers maximize their vertical GRF under their lead foot at P4. Sasho MacKenzie made the ridiculous claim that maximising the vertical GRF under the lead foot at ~P5 was highly correlated with maximizing clubhead speed at impact and he posted the following image to support his unscientific opinion.
SMK actually talked about when the clubshaft is vertical, which is closer to P5.2 (rather than P5) and he claimed that there was a very high correlation coefficient factor of 0.91 in his study of the relationship between the magnitude of the vertical GRF at P5.2 and driver clubhead speed at impact.
Scott Lynn of Swing Catalyst thought that it made no sense and he examined his data base of pro golfers and published his results.
Note that he found a very low correlation coefficient factor of 0.33.
Note that many pro golfers, who had a high clubhead speed of 110 - 120mph at impact, had a low lead foot vertical force measurement of <1.2 at ~P5.2 and some even had a value of <1.0, which means that they were not even pressure-loading their lead foot at P5.2.
If Brendon was being rational and logically looking for causal connections between lead hand grip squeezing pressure and another biomechanical factor, then he should be looking at pelvic motion and lead shoulder socket motion between P4 => P5.
Consider Jamie Sadlowksi's pivot motion between P4 => P5.
Image 1 is at P4, image 2 is at P4.5 and image 3 is at P5.
I have drawn a small green circular marker over his lead shoulder socket at P4, a small yellow circular marker over his lead shoulder socket at P4.5 and a small blue circular marker over his lead shoulder socket at P5 to show how much his lead shoulder socket is moving between P4 => P5 - thereby pulling his lead arm down from being near-vertical at P4 to becoming horizontal at P5. Note how much his lead hand has moved from P4 => P5 and it is obviously applying a large amount of linear pulling force with respect to the club handle between P4 => P5. To assert that his lead hand's grip squeezing pressure is likely going to be maximum at P5 is not surprising and it is self-evident to me that he must surely be squeezing the grip with his lead hand with a lot of squeezing force at P5. However, the magnitude of the squeezing force is not the major causal factor allowing him to generate a lot of lead hand linear pulling force with respect to the club handle by P5 and the major "real life" major biomechanical factors responsible are the fact that he has squared his pelvis by P5 and thereby rotated his lead shoulder socket counterclockwise a lot by P5 while maintaining a large X-factor measurement and the "real life" fact that he has lowered his lead arm a lot by P5. Whether he has/has not maximised his vertical GRF under his lead foot by P5 is irrelevant!
![](https://www.youtube.com/watch?v=gh8R6NHnwto&t=565s) Jeff.
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Post by dubiousgolfer on Jul 19, 2024 5:53:25 GMT -5
Dr Mann
I also interpreted that SMK graph as implying maximising vertical GRF at club vertical but apparently that is incorrect.
At around P5 the club is also being linearly pulled downwards via the arms , and that will actually decrease the vertical GRF for that phase of the downswing. You can try this yourself just standing on a weighing machine with your arms horizontal, and then bring them down quickly to your sides (using just muscular contraction of the shoulder girdle muscles ), keeping the rest of our body still. You will note that the weight measurement will momentarily decrease.
SMK found that a diverse group of golfers (including pros) all attempted to 'try' and maximise their vertical GRF at club vertical (it wasn't their actual maximum vertical GRF at that point). His graph just shows that golfers who were more successful in making their vertical GRF 'as large as possible at club vertical' showed a correlation with increase in clubhead speed.
DG
PS. I'm unsure whether SMK's graph is of any practical use.
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Post by dubiousgolfer on Jul 19, 2024 6:07:43 GMT -5
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Post by imperfectgolfer on Jul 19, 2024 6:48:03 GMT -5
Yes, I am aware of the phenomenon - but its effect is very small and passive and only relevant if there is no nervous system input into the forearm muscles resulting in a zero grip pressure scenario, and it has no relevance when it comes to golf swing biomechanics. Jeff.
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