serve, off center hits problem

gull_man

Rookie
I often don't serve the ball in the sweet spot for the flat serve. also, the second serve doesn't feel like it's hit with a solid kick brushing connection . any tips on how to correct this problem? maybe i should just watch it and aim center, and it will happen automatically without thinking? or something else? seemed better though when i made the windup faster - perahps the racket synchronizes better when it's more free flowing.
 

Chas Tennis

G.O.A.T.
Most of the serve ball impacts that I see in high speed videos are in the half of the racket's face that is away from the handle and toward the top edge of the racket. This is probably because the racket strings have a higher speed the farther away from the handle that the ball is impacted.

Isn't the sweet spot toward the racket face center or a bit closer to the handle?
http://www.physics.usyd.edu.au/~cross/tennis.html

This thread has some pictures of ball impacts, mostly for spin serves -
http://tt.tennis-warehouse.com/showthread.php?t=489960

Most of the thumbnails show ball impact on the racket face. Mostly the type of serve is uncertain.
https://vimeo.com/user6237669/videos

Impact toward top edge of racket face and away from the handle.
471252542_960.jpg

https://vimeo.com/91748883

Google search: pictures tennis serve ball impact
https://www.google.com/search?q=pic...8A9KVyAT7wICQDQ&ved=0CCgQsAQ&biw=1113&bih=670

You need to take some high speed videos to see your serving motion and where your ball impact is on the face of the racket.

In bright sunlight and using the wide angle zoom setting this low cost basic high speed video camera, at $150, is capable of showing your serve with small motion blur.
http://tt.tennis-warehouse.com/showthread.php?t=484212
 
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gull_man

Rookie
thanks for these articles. i will study them. but is there any advice to make this "correct contact" occur all the time? i know when i hit it well enough - the ball feels good on the racket face and moves faster.
 

Chas Tennis

G.O.A.T.
Most players are doing a less effective versions of an internal shoulder rotation (ISR) serve that they developed themselves. Some players may be hitting 80 MPH serves using various other types of arm swinging motions. ? All pro players with high level serves are using an ISR serve and many have very effective and safe ISR serves. They were most likely coached for years to develop their ISR serves. See my Vimeo videos of pro and recreation players serving and look for the amount and speed of ISR.
https://vimeo.com/user6237669/videos

My weak ISR. Watch the tape on my upper arm.
https://vimeo.com/21512296

Strong pro ISR. Watch the shadows of the arm bones at the elbow when they rotate. ISR is over in 1/4 second, easy to miss.
https://vimeo.com/27528701

The frame rate of high speed video is needed to see what you are doing. I tend to leave parts out and the video can show those right away once you know the right video check points.

Once you have a way to get feed back from high speed video - and understand the stroke that you are after - I believe that you have to practice and program "muscle memory" (which really might not involve muscles at all but sequences of nerve signals...?). I believe that learning strokes is difficult and involves trial and error. The motions for the serve require muscles to be pre-stretched, let's say 300 milliseconds before impact, then those muscles are used for the final racket acceleration, 30 milliseconds, before ball impact. I believe that timing has to be learned by trial and error. The body's sense used to learn this timing is probably by 'feel'. How does a better ball strike feel? Different nerve timing patterns feel different. The nerve timing for an effective sequence of stretch shortening cycles is found.

If you try to make good ball contact but leave out the pre-stretch of the muscles 300 milliseconds before impact, and then practice this poor technique for a few thousand serves, you would learn the wrong timing for the stretch shortening cycles used in the serve.

Practicing serve once you have a clear idea of what you want to do with video checkpoints for the ISR serve I guess takes thousands of practice serves. Of course, a well qualified instructor can speed up learning what to do a lot.

I don't know how many balls should be hit in a serving practice secession. For me, the first 100 practice serves often don't usually feel as good as the second 100 balls. Much above 200 and I worry about doing too much for my body. I have not been practicing.

See the Ellenbecker video on shoulder safety for the serve.
I believe that serving with ISR is never forced and could cause injury if practiced incorrectly. Here are some known issues. With forceful and rapid ISR the small external shoulder rotator cuff muscles have to be conditioned to keep the ball of the humerus in place and to stop the arm rotation in the follow through. See recommended shoulder conditioning exercises. Easy, light exercises.

There are also the important safety issues related to technique such as the shoulder high orientation for the serve to minimize impingement risk. Just one very bad motion can cause injury.

1) Jim McLennan short video on the rotator cuff, impingement and serving
http://www.youtube.com/watch?v=lTRvxaBMh8s

2) Todd Ellenbecker video on shoulder anatomy, impingement, and serving. At about minute 8 he describes the same issue as McLennan but in more detail.
http://www.tennisresources.com/index.cfm?area=video_detail&vidid=3712&ATT=&reso=lo

If you are concerned because you are having pain, how can you determine that the technique that you use is OK? You have to study and know the proper technique and verify that you are doing it with high speed video or find a well qualified instructor. Keep in mind that the more rapid motions during the serve cannot be seen by eye or even 60 fps video so an instructor who uses HSV is a plus.
 
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gull_man

Rookie
i should digest all this and i plan to as soon as i get a chance. but i seemed to have had a break through today. i tried doing the windup faster - i've been slowing it down for learning purposes - and presto, it happened! i seem to hit the ball in the correct sweet spot (upper sweet spot) now. it feels good and moves faster. even without a knee bend it's more powerful. seems to me the windup must be continuous and relaxed and free flowing and the proper connection is made. if anyone has any more tips let me know. thanks
 
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