November 23rd, 2012, 10:34 PM
Jamie Sadlowski's hip rotation into impact
To get an accurate idea of a player's hip rotation using video, you need to use at least two camera angles. That way you'll get a reasonable equivalent of a 3D perspective.
Here is Jamie from about about 0.05th of a second before impact, with both a rear and a front three-quarters view; each frame is 7/300ths (0.023th) of a second apart.
As you can see, the distance traveled at the outermost belt loop (in red) is pretty much the same between each frame, indicating a relatively constant angular velocity into impact. The innermost belt loops (the blue and the green) are close to the axis of rotation and should not be considered for this analysis. Naturally, those are what The One-Eyed Manzella looked at. Is that what his scientists would do???
November 23rd, 2012, 10:53 PM
That's some piss-poor scientific terminology there Jeffy... I doubt you'd let anyone else get away with it.
Originally Posted by Jeff Martin
Besides... JS's belt loops moved a greater distance in the frames prior to these last three. What does that mean to you?
November 23rd, 2012, 11:00 PM
Originally Posted by Cloran
Clearly, you know nothing about me or how science actually works.
November 23rd, 2012, 11:08 PM
Originally Posted by Cloran
The blue and the green? They are close to the center of rotation and should be ignored.
BTW, I thought your unprovoked, antagonistic behavior towards Dariusz on the Manzella forum today was very offensive. I really don't want people like you posting here. Adios.
November 23rd, 2012, 11:31 PM
"Voice of reason"?? Nope. Douche bag...
For some reason, I thought you were reasonable and decided to cut you some slack when you came by and busted my balls the past couple of days. But when I saw you taunt and provoke Dariusz today on Manzella's forum for absolutely no good reason, I decided to ban you. Assholes like you should be shunned everywhere.
November 24th, 2012, 12:09 AM
Jeff Mann lays waste to Manzella's latest video...
For those of you that can't access the Newton Golf Institute...
November 24th, 2012, 12:35 AM
Uh, MY world is crashing down???
Over the past two days, Manzella has posted four MATT analyses that ALL falsify Finney's cherished kinetic sequence theory. I'm pretty much loving that!!!
November 24th, 2012, 01:00 AM
I never said that...
November 24th, 2012, 01:01 AM
Well, someone over there finally gets one right...
Yep, you are correct, sir.
November 24th, 2012, 02:40 AM
OK, just for fun, let's take Manzella's analysis at face value...
According to Manzella's most recent Vimeo video, Sadlowski's hips start to decelerate 8 frames before impact, which, at 300fps, is just 0.03 of a second (analyzed properly by using at least two views, I don't see any decel before impact, but we're having fun here, and, yes, that's three hundredths of a second before impact).
However, the typical TPI graph has the hips beginning to decelerate one-tenth of a second before impact, more than 3X sooner. So, which one do we follow? Sadlowski, who doesn't begin to decelerate (according to Manzella) until three hundredths of a second before impact, or TPI, that advocates a decel that begins a tenth of a second before impact? That shouldn't be a hard question to answer...
And, if Sadlowski is your model, how far off can you be if you try to have your hip rotation peak at impact? Just three hundredths of a second, if you believe Manzella.
November 24th, 2012, 12:45 PM
A nice overhead view of "Jamie Sadlowski"
The linked video is said to be from Motion Reality, the company that designed the TaylorMade MATT system, so presumably it is a humanoid representation based on reflective markers. It appears that the light green line represents the hips; I can't really tell what the other lines represent.
From the top to impact takes about 36 frames by my count. Assuming 0.2 seconds for the downswing, each frame represents about 0.0056 seconds, or a rate of about 180 frames per second. In the video below shot at 300fps, Jamie takes almost exactly 60 frames from the top to impact, so 0.2 seconds for the downswing sounds like a good assumption.
Unfortunately, we can't read the green text in the upper left corner which appears to be the angle of the hips relative to the x-axis. But we can estimate what is going on.
At the top the hips are about 42 degrees closed. To get to where the hips are about square to the x-axis (1 degree open) takes about 16 frames. Since the hips traveled about 43 degrees, that is a rate of about 484 degrees per second. By impact, 20 frames later, Jaime's hips are about 51 degrees open. Since they traveled 50 degrees, that's a rate of about 450 degrees per second, a decline of 7%. Overall Jamie's rate of hip rotation is about 465 degrees per second from the top to impact.
However, looking closely at the video, we can see that the hip rotation starts to stall one frame (about 6 one-thousandths of a second) before impact, rotating just 0.5 degree in the last frame, a rate of about 90 degrees per second. However, in the prior two frames, the hips rotate almost 5 degrees, for a rate of about 450 degrees per second. I can live with that kind of deceleration.
November 24th, 2012, 01:16 PM
See Bman was right.....lol
November 24th, 2012, 01:46 PM
Some charts from Tapio...
I assume these are the player's hips as measured with 4DSwing:
As he told us a year ago, some players he has measured accelerate the hips to and through impact. And they are long.
November 27th, 2012, 07:11 PM
Finally had the time to frame through the entire Sadlowski overhead view...
Not only is the boot-legged video Manzella posted too blurry to read the displayed numerical data, the y-axis has been shrunk relative to the x-axis, distorting all angle measurements. To add insult to injury, Manzella's Vimeo channel doesn't permit downloads, so I had to record it off the screen AGAIN so I could go through it on a video editor. For anyone else that wants to frame through and measure hip angles, I uploaded my recording to YouTube where anyone who'd like to can download it.
To give you an idea of the y-axis distortion in Manzella's boot-legged video, the angle drawn in the screen capture below should be 45 degrees if the x-axis and y-axis were scaled properly (i.e., equally). As you can see, the angle is understated by about 8.5 degrees! That means Jamie's hips are closer to 50 degrees shut at the top of the backswing and 60 degrees open at impact.
Accomplishing 110 degrees of rotation in the space of 0.2 seconds requires an average rate of rotation of 550 degrees per second!!! That's insane. As you can see in the chart below of TPI data, the average peak rate of rotation for the tour pros they measured is just 434 degrees per second.
As you'd expect, something recorded off a video screen at least a couple times is going to be jumpy in spots and perhaps lose some frames here and there. But, this video captures the entire downswing and the story it tells is pretty simple: Sadlowski's hip rotation during the downswing is at near constant velocity, as my V1 belt-loop exercise above suggested. In fact, Jamie's hip rotation from top to impact has almost a perfect linear fit correlation (0.9990!), with drop offs in speed of rotation at just the beginning and end of the sequence.
Below I have graphed the data I measured off of the video. The red line is Jamie's hip rotation in degrees, with negative values representing closed hips and positive being open. As I mentioned above, these angles are quite understated because of the distortion to the x-axis. As you can see, even though the slope of of the hip rotation throughout the downswing is nearly constant, the data pulled off the video by hand was pretty noisy and caused the frame-to-frame rate of rotation calculation (the blue line) to be pretty jumpy. I smoothed the ROR data (shown in green) to better reflect reality (you don't really think Jamie's hips accelerate and decelerate like a yo-yo during 0.2 seconds??).
So, what does this tell us? The first thing that is obvious is Jamie's hip rotational velocity does not peak when the hips are square (the vertical black line) and then rapidly drop off by a third or a half like the TPI/kinetic sequence model: there is, in fact, a second velocity peak (reflecting a second phase of acceleration) and velocity is maintained until the very last frames before impact, when his hips are nearly 60 degrees open and the upper body/arms/club moment of inertia is at its maximum.
Second, we know that to maintain this velocity Jamie must be exerting increasing amounts of pelvic torque in the downswing. As the club and arms extend in the downswing, the upper body moment of inertia increases, putting a higher load on the body's torque generators (rotational acceleration = torque divided by moment of inertia; if MOI goes up, torque must also go up or velocity will drop). So, from a biomechanical perspective, he is increasing his applied torque throughout the downswing, reflected in the second period of acceleration. That strongly suggests that his biomechanical intent is to accelerate the hips during the entire downswing.
A far as I'm concerned, this data, as well as the Hogan analysis I did the other day and the 4DSwing analyses shared by Tapio, blows up claims that deceleration is essential to all good golf swings. Deceleration may be the ultimate result in most or nearly all cases, but, IMO, it should be caused by increasing moment of inertia, not decreasing torque.
BTW, this is a 4DSwing analysis of a young European tour player with four wins. His hip rate of rotation is in blue and peaks at impact.
November 28th, 2012, 09:39 AM
Just want to take a moment and congratulate you and Kelvin for putting to rest with incontrovertible data the pervasive "kinetic chain snapping" golf swing myth. Thomas Huxley said it best:
The great tragedy in science: the slaying of a beautiful hypothesis by an ugly fact.
One of the reasons the one eyed Manzella banned me so many years ago is because I scoffed at that notion (which defies common sense) and he can't tolerate dissent. I can't tell you how pleased I am to see the better researchers of the golf swing such as yourself and Kelvin arriving at the same conclusion I did and are able to back it up with even more scientific data. That said, the myth will undoubtedly persist, like so many others have in the past, for a very long time come.