S
sennoc
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Chas Tennis,
Thank you very much for information about camera. Looks like I'll buy it.
Look at Fujifilm HS10 too, very good camera for tennis purposes (my choice).
Chas Tennis,
Thank you very much for information about camera. Looks like I'll buy it.
I even do not understand the term – ‘energy transfer’ in relation to the human body. I spent a lot of years in the fields where we designed special devices (antennas, cables, wave guides etc.) to transfer electromagnetic energy. Right now it is very big problem to transfer properly electrical energy inside of the very fast computer processors. I think human body doesn’t have special mechanisms, for example, to transfer left ankle energy directly to the right wrist.The whole issue of the kinetic chain and energy transfer in the serve from one link to the other by acceleration - then abrupt deceleration, causing another link to get stretched more in its movement, thereby enhancing its own acceleration is pretty complicated.
Thank you very much for information about camera.Look at Fujifilm HS10 too, very good camera for tennis purposes (my choice).
The ability to measure and calculate millions of numbers will not further the understanding of tennis strokes. Biomechanics alone is not the holy grail of sport understanding, and there are some issues the current methods of biomechanics can't address.
OK. Right now we know that we don’t know anything!?To quote Brian Gordon:
OK. Right now we know that we don’t know anything!?
To quote Brian Gordon:The ability to measure and calculate millions of numbers will not further the understanding of tennis strokes. Biomechanics alone is not the holy grail of sport understanding, and there are some issues the current methods of biomechanics can't address.
Russian proverb: Less knowledge = more healthiness.Did you ever hear of the saying "the more you know, the less you know...?"....
or to quote a Chinese philospher:
"Without stirring abroad, one can know the whole world,
Without looking out the window one can see the way of heaven.
The further one goes, the less one knows". Lao Tzu
High Speed Video Measurement of Racket Spin from Pronation, Non-Serving, 90 d. Bent Elbow.
There has been discussion of rotation produced by pronation and the upper arm rotation powered by the shoulder. This was a revelation to me as I had never thought of shoulder rotation as also contributing to this familiar rotation, obvious now.
Nicely clarifying the distinction between pronation and shoulder rotation:
I wanted to get an idea of the magnitude of the pronation without the shoulder rotation.
Russian proverb - less knowledge more healthiness.
Did you ever hear of the saying "the more you know, the less you know...?"....
or to quote a Chinese philospher:
"Without stirring abroad, one can know the whole world,
Without looking out the window one can see the way of heaven.
The further one goes, the less one knows". Lao Tzu
I envy you. I cannot comprehend your or sennoc idea, "release as efficiently as possible the built up energy”. Behind every kinetic energy is always force. The force produces work and work is energy. When racquet meets the ball, the energy releases automatically. We just have to take care about racquet face orientation and direction of the racquet speed. Tiw we should “actively powering the racquet towards the ball” Unfortunately I’m engineer and my brain doesn’t allow me to forget about quantitative analysis. I’m cursed man. It’s really very sad.Or, to put it simply: Ignorance is bliss!
I am still grappling with the world of possibilities and new insight that sennoc has opened up. Maybe they were always there, and maybe some coaches who have given wonderful tips/cues instinctively knew how it all worked - but man, I am looking at the whole thing differently now!
Basically, there seem to be (at least) two ways of hitting the ball. In one way, there is more emphasis on actively powering the racquet towards the ball, as most of us tend to do. In the other, the emphasis is to release as efficiently as possible the built up energy. Forget the math and any quantitative analysis, and look at it qualitatively - these are totally different ways of thinking about the same problem, and will impact coaching techniques, IMO. Or maybe this is all well known and I am just waking up... but I have started looking at every stroke in a new light since yesterday!
I envy you. I cannot comprehend your or sennoc idea, "release as efficiently as possible the built up energy”. Behind every kinetic energy is always force. The force produces work and work is energy. When racquet meets the ball, the energy releases automatically. We just have to take care about racquet face orientation and direction of the racquet speed. Tiw we should “actively powering the racquet towards the ball” Unfortunately I’m engineer and my brain doesn’t allow me to forget about quantitative analysis. I’m cursed man. It’s really very sad.
Here we go...
http://www.vimeo.com/20768407
(I hope Will won't kill me)
The movie is waiting in a queue, please wait an hour or so (I'm to tired, it's really late here).
Please download the movie and compare both strokes frame by frame.
Can you please post your own video about pronation measurement? If it’s good I buy this camera (Casio FH100).
Here we go...
http://www.vimeo.com/20768407
(I hope Will won't kill me)
The movie is waiting in a queue, please wait an hour or so (I'm to tired, it's really late here).
Please download the movie and compare both strokes frame by frame.
There are huge similiarities between both strokes, if you know where to look at.
And there are huge differences in technique between both strokes, if you know where to look at.
In the article http://www.facebook.com/notes/tennissmith/2-biomechanics-workshop-notes-by-robert-wojcik/145086245548662 step 12 Robert Wojcik stated, “Swing is 1.7 times faster if you immobilize non-dominant side”. What does it mean?Of course they are. But that's obvious for everyone. And it's not obvious for everyone that there are strong similarities. This is the power of knowledge: to discover the same things between different phenomena. This is how science evolves.
Chico9166, left hand as important part of every stroke is nothing unusual. But look at Federer's left hand. He bends it, so he reduces radius of rotation and his shoulders are colinear during stroke. Great, but I do different thing - I'm loading my left hand by energy transfer along it and then, when its energy is higher, I bend it. The result is different, because forces are different. Try to copy my motion and Federer's, without your racquet. You will immediately see the difference.
Chas Tennis,Here is the video for measuring pronation magnitude. Casio EX FH100, 240 fps, 1/800 sec exposure time, ISO 3200. Quicktime has convenient frame-by-frame control by using the arrow keys.
107 MB long so you may want to watch it there. I just got the VIMEO account. I did not see how to do stop action, frame-by-frame on Vimeo.
http://vimeo.com/20779304
Video could be improved with more lighting, maybe white tape on the racket frame, etc.
In any case, sennoc, modesty is not one of your strong points...:lol:There are huge similiarities between both strokes, if you know where to look at.
As you can see on my movie, Federer is using his left hand at forehands in less technical way than me (yuppi, I'm better than GOAT! ).
...
It's also hard to find steady shots with Federer at full speed (in most cases replays are slower). So, I have to check my huge base of Federer's matches (over 100 DVDs), choose his shots, then try to replay the situation on the court, what is not quite easy (it's easier to hit a good stroke if you do not think about that). But I'll try to do that, I want to make some conclusions.
I'll made some better videos in the future. Unfortunately, now I have limited angles where I can record my game. It's also hard to find steady shots with Federer at full speed (in most cases replays are slower). So, I have to check my huge base of Federer's matches (over 100 DVDs), choose his shots, then try to replay the situation on the court, what is not quite easy (it's easier to hit a good stroke if you do not think about that). But I'll try to do that, I want to make some conclusions.
".
So take a service to compare. It is much easier to find and it was the initial issue.
But more important it will prove my point that you know a lot about key caracteristics but it will not give you the inner technique.
OK, I'll do the movie. Unfortunately, I can't make better videos of my serves (need 2-3 months to compensate 5 months of winter - and more serve practice than one recreational set per week), so I will use that accidental serve from one of my previous videos.
What's inner technique?
So you have to wait till June. Maybe May at good weather. I promise I'll do the movie, I'm personally interested.
Also, in my opinion you do not exactly understand the connection between the power of knowledge and good technique in amateur tennis. Usually, amateur technique is horrible. It's so full of errors that if you suddenly discover a law or rule, you can rapidly improve. That's why knowledge works good here.
The problem is that every change is artificial at the beginning. You have to work many hours (usually a few hundred at least) to learn how to use new element as a "natural" one. This is something you probably understand as inner technique. But this is just a simple process of many, many repeats.
That's quite obvious and natural that pure knowledge doesn't quarantee really good technique. During repeats, you have to control your results - by recording your strokes as example. By watching your body in the window. By tracking your shadow on the court. You move your new scheme of the stroke into subconsciousness and it becomes more and more "natural".
My forehand is my only "natural" stroke now, serves are very artificial. But they won't be artificial. In a year, maybe two. The same with other strokes.
There are huge similiarities between both strokes, if you know where to look at.
As you can see on my movie, Federer is using his left hand at forehands in less technical way than me (yuppi, I'm better than GOAT! ). At the beginning of swing, his hand is straight and high. My left hand is bend and closer to me, what helps to rotate shoulders around hips (due to angular momentum conservation law). Also, my hand moves in horizontal plane. As a result, I do not see my left hand during stroke and my visual system is not disturbed. I can concetrate on the ball only.
You can also see that Federer does not use energy transfer along his left hand. My left hand extends - it "stores" kinetic energy of the body - and then rapidly bends, what means that energy is transfered back to the body (once again, due to angular momentum conservation law). So, my left hand works as another source of energy at shoulders rotation, while Federer's left hand just does not disturb motion of his shoulders (this is a small but important difference). I'm much older, but I can hit quite similar forehand in terms of dynamics, as you can see on the movie. I think that's quite amazing. I'm an amateur. This year I spent 30 hours on the court, while he is playing a few hours per day, he has the best coaches, free access to courts and infrastructure etc.
So, my swing begins with left hand which works as a source of energy. Now you check the role of left hand during serves, and you will be surprised. It's exactly the same. On sufficiently deep level of understanding, both strokes are identical at this point. That's very, very important, because if you understand the role of left hand at forehands (what seems to be easier), you "magically" improve your serves.
If you had to hit your forehand on the run against Rafa and Djoker, stop on a dime after hitting it, and retreat as fast as possible to your backhand corner to hit an inside out forehand...
... would you engineer your forehand to be like it is now...
... or would you engineer it with your left hand out for balance during your rapid movement like Fed does?
Second question (even though I think I know the answer):
Against the players you are playing, do you think your forehand is better engineered for movement and hitting than the type of forehand Fed hits?
Sennoc,
…………………………….
Your serve technique doing more harm than good? http://www.youtube.com/watch?v=GgdX...y&list=PLD4C2A7ED17FABE64&index=31&playnext=8
Preventing Rotator Cuff Injury http://www.youtube.com/watch?v=lTRvxaBMh8s&feature=related
http://www.tennisresources.com/index.cfm?Rotator cuff injury ATT=&area=video_detail&basicsearch=1&media_name=&rv=1&vidid=3712
Not quite sure what you mean by trying to rotate the racket. With arm pronation, the racket rotates. Hitting on the left side of the ball is correct, since good servers hit up and inside out.7) Racket Spin. On a serve video examined in post #106, the racket spins with enough of a rate so that the strings have a considerably different velocity from the right side to the left side of the strings. Because of the spin the racket could be pictured with varying velocity vectors all over its string face. The vectors would vary in magnitude and direction (non-parallel). The effects of racket spin velocity variation and ball impact location have probably been studied and some references would be interesting. As for me, I’m going to try and rotate the racket rapidly and to hit the ball a bit on the left side.
There is an edit button at the end of your posts....Can the posts be edited after they are posted somehow? I can't find out how to do that.
Seems reasonable that the pros would hit high on the strings. I have not looked at videos to estimate that effect. I don't know the velocity difference between the top and bottom of the frame but with wrist flex it is probably large. Any references or studies of the pro's?