Post by imperfectgolfer on Jul 27, 2020 11:49:47 GMT -5
Consider this Hack Motion seminar video featuring James Leitz.
James, like Jon Sinclair, is a proponent of the "idea" that the lead wrist rapidly-massively extends through impact in a pro golfer's full golf swing action.
James states in the video that he first became aware that the lead wrist extends through impact in 2006 when he was introduced to Phil Cheetham's AMM-3D system.
Here is a typical pro golfer's AMM-3D graph - copied from the JL video.
James, like Jon Sinclair, is a proponent of the "idea" that the lead wrist rapidly-massively extends through impact in a pro golfer's full golf swing action.
James states in the video that he first became aware that the lead wrist extends through impact in 2006 when he was introduced to Phil Cheetham's AMM-3D system.
Here is a typical pro golfer's AMM-3D graph - copied from the JL video.
Note that the lead wrist is extended at P4, and it then moves towards flexion during the downswing and it's flexion-value peaks just before impact. Then it reverses direction and moves in the direction of "lead wrist extending" through impact into the followthrough. Note that there is a blip-plateau in the lead wrist flexion-extension graph immediately post-impact (probably between P7 => P7.2) which they (JL and JS) claim is due to ball collision. So, they choose to ignore that blip-plateau phenomenon in their analysis and then produce this type of "smoothed-out" graph as being representative of a tour pro golfer.
The black graph represents the mean value and the blue-green graphs represent one standard deviation.
At impact, the mean lead wrist flexion value is roughly 0 degrees, and in the mid-followthrough (undefined position) it is 23 degrees extended.
So, what does James conclude?
Here is a capture image from his video.
Note that he states that the lead wrist is moving towards extension at >700 degrees/second and he states that it is another speed component. In the video, JL actually referred to the phenomenon of "lead wrist extending" at impact as being the 5th power accumulator!!!!
Let's consider the "idea" that the lead wrist moving in the direction of extending is a swing power source that can increase ball speed.
Consider two pro golfers swinging their driver at a clubhead speed of 120mph at impact. Imagine that the first pro golfer maintains a FLW through the impact interval while the second pro golfer's lead wrist moves towards "lead wrist extending" through the impact interval at 700 degrees/second. How much lead wrist extending will happen during impact, which lasts 1/4000th of a second, in the second golfer? According to my calculations, it works out to 0.17 degrees. Do you think that moving the lead wrist in the direction of "lead wrist extending" by 0.17 degrees (just before impact or during impact) will significantly increase clubhead speed? I personally think that it irrational to believe that the phenomenon of "lead wrist extending" through impact should be regarded as a speed component, and I think that it's particularly audacious to think of it as being the 5th power accumulator!
Now, let's consider the immediate impact zone between P7 and P7.2+ where the clubhead moves ~2 feet along the clubhead arc during that time period. How much more will be the lead wrist be extended at P7.2 if the lead wrist is extending at 700 degrees/second?
The average tour pro swings the driver at 113 mph and lets say clubhead speed is reduced by 20% at impact, that would mean a speed of about 90 mph = 132 ft per second post impact.
132ft is equivalent to 1 second.
If the club travels approx 2 ft post impact between P7 and P7.2, the time taken would be approx (1/132) x 2 = 0.0152 secs (I'm assuming a straight path post impact as an approximation).
132ft is equivalent to 1 second.
If the club travels approx 2 ft post impact between P7 and P7.2, the time taken would be approx (1/132) x 2 = 0.0152 secs (I'm assuming a straight path post impact as an approximation).
If the lead wrist is extending at 700 degrees/second, then in 0.0152 seconds, it will extend ~10.6 degrees. That figure ignores the fact that ball collision could possibly (although I think unlikely) slow down the speed of the "lead wrist extending" phenomenon happening immediately post-impact (even though the peripheral clubshaft will routinely bend backwards as a result of ball collision).
Now, if the lead wrist is actually extending ~10 degrees between P7 and P7.2, that actually represents a small amount and it does not represent "massive" lead wrist extending (a term favored by Jon Sinclair).
Most importantly, that 10 degrees represents the mean value, which would include DHers and non-DHers. I strongly suspect that DHers are extending their lead wrist <5 degrees between P7 and P7.2, and both Jon Sinclair and James Leitz are seemingly unwilling to accept that assertion! However, most tellingly, they both refuse to provide me with measurements of the amount of "lead wrist extending" happening in a DHer between P7 and P7.2.
Here is small collection of capture images of pro golfers who are DHers - hwww.perfectgolfswingreview.net/DHers.html
My definition of a DH-hand release action is based on the relationship between the lead forearm and the clubshaft between P7 => P7.2 and the clubshaft must not bypass the lead forearm (from an angular rotational perspective) between P7 and P7.2. Most of those featured pro golfers actually keep the clubshaft from bypassing their lead forearm all the way to P7.4+.
I don't have 3D graphs of all those DHers, but here are a few 3D graphs showing that the wrist is not extending significantly through impact to P7.2+.
Jon Rahm's AMM-3D graph
Note that Jon Rahm's lead wrist flexion-extension graph shows a plateau between the red and blue arrows, and there is no evidence of significant "lead wrist extending" happening between P7 and P7.2.
Here is Dustin Johnson's lead wrist flexion-extension graph (as measured with a HackMotion device) - showing only the peri-impact time period.
The green graph represents DJ's lead wrist flexion-extension graph. (flexion is below the zero line in this graph)
The lead wrist is flexed at P4 and then moves towards "extending" in the later downswing. At impact, it is still slightly flexed. Note that it then moves towards increased flexion immediately post-impact between P7 => P7.2+ before it starts to rapidly extend in the later followthrough. JS and JL may assert that the increased lead wrist flexion happening temporarily between P7 and P7.2 is due to ball collision, but then it should be seen routinely in all the HackMotion graphs of pro golfers and it does not routinely happen (which even James Leitz concedes is true).
If I played "devil's advocate" and accepted the opinion that Dustin Johnson's lead wrist is not moving rapidly in the direction of "lead wrist extending" between P7 and P7.2 because ball collision is causing a temporary plateau phenomenon during that time period (as seen in that graph above) then it would actually help me to explain why Dustin Johnson can easily perform a DH-hand release action through the immediate impact zone between P7 and P7.2. What would then become more difficult to explain is why so many pro golfers manifest a non-DH hand release action through impact, where there is a large amount of "lead wrist extending" happening between P7 and P7.2, considering the "fact" that ball collision should be temporarily preventing the "lead wrist extending" phenomenon from happening during that time period (according to Jon Sinclair).
If James Leitz and Jon Sinclair were truly interested in understanding/explaining the biomechanics underlying a DH-hand release action, then they should publish the 3D graphs of all the pro golfers who use a DH-hand release action between P7 => P7.2+.
Jeff.