Recent content by Chas Tennis

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    Junior Twist Serve

    Too bad if you have to log on to view a video. Links have recently changed including now video links. I wonder why? That should really reduce the number of views for Vimeo in comparison embedding that shows a thumbnail for the video. I point out differences or what should be examined farther...
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    Junior Twist Serve

    In your first video, view from behind, stop on impact and compare the angle of the racket shaft to the horizontal. Stop on impact. For single frame hold down the SHIFT KEY and use the ARROW KEYS. The video may skip frames? I hope that viewers don't have to log into Vimeo. This is the first...
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    Serve speed based more on strength or technique?

    You are exactly right about the KC, leg thrust and ESR. I think that is a clear illustration of how the KC fails. A service motion uses several sub-motions during the serve to force ESR and that stretches ISR muscles. Lets say that we are interested in leg thrust to jump and how that might...
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    Serve speed based more on strength or technique?

    Do you have a link to a reference that explains how the Kinetic Chain's segments are using elastic energy? In biomechanics and kinesiology the stretch shorten cycle is considered and not hidden.
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    is this serve in?

    I have seen nasty agruments in the above arrangement where the server is sure that the ball is good. The ad side of the court I believe is the worst. Notice in that frame, that the ball blocks the server's view of the space between the ball and line. Also, the height of the ball is not seen...
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    is this serve in?

    I placed markers on the ball trajectory before and after the bounce. On the frame after the ball is seen close to the line, the ball does not appear in one frame. I can't tell the height or location of the ball where it appears just to the left side of the line or when it disappears. This...
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    is this serve in?

    I assume that is the center line of the service box. ? 1) You can't tell with this quality of video and slow frame rate. The frame with the lowest ball shown is not likely to be the actual lowest point that the ball reached, unlikely to be during contact. Look at how far the ball moves...
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    is this serve in?

    I agree with Topspin Shot.
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    Serve speed based more on strength or technique?

    Could you explain how the Kinetic Chain Concept deals with stretched muscles and the Stetch Shorten Cycle? For example, how is the elastic energy stored in the stretched muscles that perform ISR dealt with? [ ISR - internal shoulder rotation, a defined joint motion. Called medial shoulder...
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    Biomechanics References on Tennis Strokes

    This 2018 publication deals with Titin research. Titin relates to tennis strokes through the stretch shorten cycle. On these technical research publications, I usually read the Abstract, Introduction and the Conclusions at the end. This paper has some interesting points - it assigns forces...
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    Don Budge Advised Mac To Approach Up The Middle.

    Thanks, that is a great video based on that segment. Looking forward to the rest of it.
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    Serve speed based more on strength or technique?

    All muscle shortening forces are developed in the sarcomere. 1) Titin This animation represents Titin in the muscle sarcomere, blue. Some forces are produced by elastic Titin, a giant molecule. The Titin forces are called 'Passive Forces' 2) Actin & Myosin (Titin not shown) Better...
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    Don Budge Advised Mac To Approach Up The Middle.

    The OP video is 43 minutes long. Could someone post the time of the OP quote. "Don Budge advised me to approach up the middle. Take away the passing shot angle."
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    Serve speed based more on strength or technique?

    The slow motion at 1:41 looks as if he might have used ISR plus near straight arm shoulder abduction and wrist motions. ISR is always cable of power because the lat is the largest muscle attached to the arm. (To single frame on Youtube use the "," and "." keys.) ISR can produce rapid racket...
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    Serve speed based more on strength or technique?

    Many of the sub-motions of the service motion specifically have to do with the stretch shorten cycles for certain shoulder muscles. When internal shoulder rotation (ISR) was finally realized by tennis researcher in the 1990s, some complete misconceptions were set straight. Some of the main...
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