Warlock

I put quotation marks around that statement just to show it wasn't me but now you accuse me of: Intellectually dishonest territory!!!!! Misrepresenting who says specific things !!!! Goodbye!

Many thanks for this video. I am basically trying to understand the swing geometry of what's going on when one performs the 'reverse motorcycle move' purely from an academic standpoint. If the bowed wrist was maintained (say from P6) and the downswing progressed so that the clubface was about 15 inches from the ball, wouldn't the shaft be more angulated to the inside of the ball/target line and therefore the clubface more open approaching impact (as in picture D that I previously posted)? I am assuming that there will still be some angle between the lead forearm and club shaft (ie. some radial deviation in the lead wrist) while retaining that bowed wrist position. The statement I posted was from Jon Sinclair, but I must admit I had trouble getting my head around his sentence "I cannot think of a player off the top of my head that does not have less supination at impact than when they started." I'm assuming he means that most players he's measured have less lead forearm supination at impact (ie. more pronated) than at address. PS. Hooray! I've just received an email explanation from Dave Tutelman which I now understand, so no need for any more answers to my questions.

Would this statement cover it better? "The wrist are very complexed. You have to look at both to really determine how the club is being manipulated. First of all, a position in and of itself neither opens or closes the club face. So these players having flexed lead wrist does not mean they have closed the club. The grip has a lot to do with what is happening as well. As a very general rule a player with a lot of flexion in their wrist at the top will actually start closing the club face later than one with a lot of extension. I am talking about world class players here. After club transition flexed players will tend to move toward extension a bit before going hard back to flexion. I cannot think of a player off the top of my head that does not have less supination at impact than when they started. This is a tricky measurement though. AMM does not do the shoulder girdles so that can alter it some. Moving toward flexion closes the club face at the top but then acts and opens it at impact. Pronation/Supination takes the in and out of plane until you get more ulnar deviation then lead supination/ trail pronation closes it. I would need to do a complete study but I would doubt highly that there is less or more forearm movement in a flexed wrist over a extended one. If you are talking about higher or lower ROC I would also say that is a myth. It is what people want to believe. It fits nicely with a narrative."

So is bowing the lead wrist a better way to get forward shaft lean rather than a means of early clubface closure relative to club path?

Difficult to explain in words but I tried to draw some pictures below.

I'm assuming that the 'motorcycle move' closes the clubface relative to the swing path in the early downswing so that you don't have to rotate the forearms as much in the late downswing to square the clubface by impact? I've always wondered how they can prove whether that actually happens or not. For example, if I got into an impact fix position with a flat left wrist and then just purely bowed it, won't the shaft move more inside relative to the ball-target line? Wouldn't the clubface be actually more open to the ball-target line? Is the motorcycle move just pure flexion of the lead wrist or is it flexion combined with a bit of supination?

The 1st article was published 5th Jan 2012 The 2nd article has 11/06/2019 on each slide.

Found another interesting article by Dr Sasho MacKenzie , so maybe that 22% increase in clubhead speed is due to linear work applied to the club and not forearm rotation. In the original article that I mentioned in my opening post he said: "The clubhead speed for Sim3 (44.1 m/s) was 22% higher than that generated during Sim1 (36.2 m/s), which indicates as to how much active rotation of the forearm from a muscular torque can contribute to clubhead speed" Here is another article I found where he conducted regression testing (which I'm not too familiar with to be honest): Forces Applied During the Swing (rccssc.ca) It says the following: Linear Work predicts 90 % of the variability in CHS by itself Angular Work adds extra 9% (does predict 44% if entered alone first) I'm assuming that this recent article is more up to date on what can increase clubhead speed.

So, if I've interpreted this correctly: 1. SIM1 - The 'In Plane MOF' unhinged the wrist and angularly accelerated the clubhead earlier in the downswing than SIM3. This is why the clubhead speed could be nearly the same as SIM3 (hinge intact ) at the 0.2 sec mark. This 'In Plane MOF' will continue accelerating the clubhead until impact. 2. SIM3 - The 'In Plane MOF ' that starts to unhinge the wrist at 0.2sec is greater than SIM1 and will accelerate the clubhead to an even greater speed than SIM1 by impact. That this forms most of that 22% increase in clubhead speed plus maybe a little extra speed caused by the active musculature rotation of the forearms. How am I doing?

You mean velocity= radius x angular velocity? An uncocked wrist will also increase the MOI of the 'lead arm/club' unit, therefore its angular velocity will decrease even as the radius increases. This is getting more complicated

Yes, that seems to make sense. Here are the MOI graphs of SIM3 and SIM1 So am I correct in assuming that in SIM3, because the MOI of the 'lead arm/club' unit is smaller about the rotational axis of the torso for a longer period, the 'lead arm/club' unit could therefore be angularly accelerated more by the torso torque generator until the 0.2sec mark (when the lead wrist starts to uncock)? That this increased angular acceleration could account for most of that 22% increase in clubhead speed? Actually, on reflection the above doesn't make sense because the clubhead speed on the bottom graph is about the same for SIM1 and SIM3 at the 0.2 sec mark.

This is what is says in that research article I attached. -------------------------------- "The clubhead speed for Sim3 (44.1 m/s) was 22% higher than that generated during Sim1 (36.2 m/s), which indicates as to how much active rotation of the forearm from a muscular torque can contribute to clubhead speed" "Sim1 started with the forearm angle set to -10 degrees (Figure 3a), which placed the center of mass of the club 7.3 cm below the golfer’s swing plane (Figure 3b)." "For both Sim1 and Sim2, the forearm torque generator was set to zero for the entire downswing. In other words, the golfer model was not capable of actively supinating the forearm to square the clubface for impact" "Simulation 3 (Sim3) was considered the reference condition, as the downswing swing was initiated with the shaft perfectly within the golfer’s swing plane and the optimization was conducted with all the torque generators available to supply energy to the system" ------------------------------- Doesn't this mean that SIM1 was still able to square the clubface without any active musculature rotation of the forearms? The forearms must have been rotated by the angular momentum of the club created by that passive torque effect.

Not disputing that the primary function is to square the clubface but if there was a way of also increasing clubhead speed by 22% wouldn't that be an added bonus? Although I suspect it would require impeccable timing to do both.

So are you saying that the club squaring mechanism is probably as per Dr Sasho MacKenzie's explanation below with little forearm musculature effort required? His research for optimising clubhead speed with his model generators both squared the clubface at impact but with a 22% increase in clubhead speed. Doesn't that mean a real golfer could theoretically also do the same?

If you look at the M_Arm graph it starts building torque above zero around P5 (left arm horizontal). I can imagine that the MOI of the club about the longitudinal axis of the lead arm is very high at that point so any small lead forearm/arm torque might not have much effect on moving the club off plane (ie. toppling the club). Although the MOI might be rapidly getting less as the angle between club and lead arm starts getting larger. The increase in clubhead speed due to forearm rotational torque must be happening much later in the downswing when the MOI has decreased. But won't that still cause the clubhead to move off the 'functional swing plane' ?

From purely an academic standpoint, I've never been able to figure out if the rotation of the forearms (mainly the lead forearm) can be used to significantly increase clubhead speed in a real golfer's swing. I've looked at Dave Tutelman's website (link below) and there seems little mention of M_Arm (ie. torque rotation of the arm/forearm) and it's relation to clubhead speed generation. Dr Sasho MacKenzie's model (with torque generators for body segments) was optimised for clubhead speed and he produced these set of graphs below. Modeling the Golf Swing The area under the M_Arm graph is 'torque impulse' which I assume will mean a change in the angular momentum of the club because the arm torque generator is directly linked to the club via the wrist joint. Does anyone with a bit of scientific background (hopefully better than mine, as I did physics a long time ago and have forgotten lots) know whether this could cause a significant increase in clubhead speed by impact? I also read this other article by Dr Sasho MacKenzie (I've attached the .pdf ) titled 'Club position relative to the golfer’s swing plane meaningfully affects swing dynamics'. It seems to be the same model being used for various simulated swings but within the text he says the following: ---------------------------------------------------------- "The clubhead speed at impact for Sim3 (44.1 m/s) was 24% higher than that generated during Sim4 (35.5 m/s; Table II). The optimization algorithm found the muscle coordination pattern that resulted in the highest clubhead speed at impact while also ensuring the clubface was square to the target line. The clubhead speed for Sim3 (44.1 m/s) was 22% higher than that generated during Sim1 (36.2 m/s), which indicates as to how much active rotation of the forearm from a muscular torque can contribute to clubhead speed" ----------------------------------------------------------- A 22% increase in clubhead speed due to active musculature rotation of the forearm seems a huge amount. Is it actually feasible for a real human golfer to create that much of an increase in clubhead speed? Sasho MacKenzie2012Clubpositionrelativetothegolfersswingplanemeaningfullyaffectsswingdynamics (1).pdf

Is this video about applying positive alpha torque into impact phony science? Many golfers could be tempted to buy the book ''Science of the Golf Swing' which seems very expensive? I looked at Dave Tutelman's analysis of this claim (link below) which makes me think it could be wrong but not 100% sure because Dr Steven Nesbit seems a well-regarded scientist. Nesbit or Kwon or MacKenzie? My favorite swing modeling pioneers, Young-Hoo Kwon, Sasho MacKenzie, and Steven Nesbit, seem to come out on different sides of an important...

I don't think John Erickson's ABS technique is about creating any extra clubhead speed through impact (ie. by accelerating the clubhead through the 0.5 msec impact period). Some of his students say they are willing to forego a decrease in clubhead speed by using a heavier clubhead while accelerating and maintaining shaft flex through impact. They are claiming that their technique will cause less dispersion of the ball for off-centre strikes which is superior to 'Swinging' (see video below). Although he does say that if you're a golfer who strikes the ball in clubface centre all day, then 'Swinging' can be very effective.

I think you make a fair point although many of his 'students' are very defensive about any science that may question some of his claims. In response to any doubters that he can create lagging shaft flex through impact, he recently posted the youtube video below. I wish he's actually made a full swing and then run it in slow motion because it can be quite easy to create lagging shaft flex with a short backswing and 'whippy shaft/heavy clubhead'.

This is his proof that he's creating lagging flex through impact without striking a ball. But if you look at his video below, you'll see what seems to be a remarkably similar frame image, but after striking a ball.

Unless I'm mistaken, this 'hitting' technique (whatever that really means) he is promoting seems to be a torso pivot driven swing of the arms/club through impact (while just passively uncocking the lead wrist). Arms being connected to the torso where body rotation squares the clubface. I can't imagine that this type of swing could create much clubhead speed unless the golfer has a very quick torso rotation. He claims this technique will keep the clubface squarer to clubhead path because he's not using any significant lead forearm rotation and that he is maintaining lagging shaft flex through impact. By doing the latter, he is also claiming less ball dispersion for off centre clubface strikes through impact.

Sorry to bump an old thread, but Dr Phil Cheetham and some other famous names seem to be actively investing in this AI technology. I'm still unsure how it all works using 2D video to convert into 3D. Is it a best estimate of kinematic data measurements? I've been viewing some of the you-tube videos and I think that Sportsbox are using Dr Phil Cheetham's 3D data that he has on tour players. Could it be that they compare the golfer body segment measurements to a 'closest match' of a tour player and somehow plot the differences in body segment positions (over time) to determine the golfer's kinematic data? Then create a best estimate of other kinematic data (not shown in 2D) by using the 3D information of the tour pro?

I've just found another HackMotion graph for DJ driver swing on one of Scott Cowx more recent you tube videos and it looks slightly different. I think the top one must be out of phase because that increased flexion happens before impact whereas in the one below it happens after impact.

His radial deviation at P4 seems to look greater than 5 degrees in this sky sports video (or is this due to parallax)? Does GEARS also measure the same figure? "Specifically what? The green line? It could be extending because the handle goes while the clubhead slows as it hits the ball. Or it's just the last little roll that adds a little flexion." Not sure I understand what you meant above. What confused me is the flexion-extension graph showing increased flexion happening just before impact. Look at graph below where it shows increased flexion from -10 to -21 degrees. How can his lead wrist flex more when the pull force on his hands can be very high approaching impact? I just wanted to know whether GEARS superior working frequency (is it 450 Hz?) corroborates similar wrist measurements as shown in HackMotion (which I think only operates at 100 Hz).

I was looking at HackMotion graphs of DJ on their website and wondering whether GEARS matches (approximately) the figures as per below? Radial deviation of only 4 degrees at the top of the backswing seems a bit on the low side even though its more difficult to do this when your wrist is bowed. The increased bowing of the wrist just before impact also looks a bit strange and wondering how he is able to physically do that?