Tennis Researchers of the world...

[EricMatuszewski]

Tennis Researchers of the world,

Stills taken from the stroke archive suggest that Rafters re-occuring rotator cuff tear was likely due to a flaw in his technique. Namely over abduction on approach to contact.

Prevously, much of the coaching world has simply chalked it up to the fact the he hit alot of kick serves.

I've always found this to be a poorly supported assumption since I've seen many players hit kick serves frequently without tearing anything.

I'd like to present these Jpegs for discussion in the forum.

One is of Marat Safin whom hits as many kick serves as anyone on tour with probably as much spin but whom has shown no sign of rotator cuff damage,

The other is of Pat Rafter whom we all know had re-occuring problems with his rotator cuff.

What I'd like you to do for yourself is a simple experiment..

1) print the two jpegs out.

2) draw small circles over the points of the shoulders of the players as well as the right elbows.

3) Draw a straight line using a straight edge connecting the shoulders.

You will see that Safins elbow is still below the line whereas Rafters elbow is above it.

Although it's not perfect, this experiment lends evidence to the assertion that Rafter abducted more than Safin does.

Over abduction is well known to be a cause of impingement and consequentially rotator cuff damage.

My point here is that the kick serve can be hit safetly when you know how to coach it correctly, and there is no reason to villify this valuable shot.

Villify poor technique, not the shot in general.

Please contribute your comments..even if you see evidence to the contrary as this is an important subject that needs to be talked about.

For added discussion I've enclosed a jpeg of Roddick. What are his chances of a healthy shoulder, when you do the experiment?

Sincerely,
Eric

The Safin Jpeg in the lower right has been added to better match the Rafter and Roddick frames. The elbow angle matches better.

[gzhpcu]

Thanks, very interesting. Vic Braden is a coach famous for not wanting to teach a kick serve unless a pupil signs a agreement not to hold him responsible for injuries. This is also why on his serve video he says to toss the ball way to the right so that over abduction does not occur.

John with his "left launch" analysis of the Sampras serve, showed how Sampras avoided this. As you mention, the shoulder - elbow angle is important.

I think Roddick looks OK.

[EricMatuszewski]

Here is the part the video seems to have omitted..

Using a "cartweel" action of the trunk, where one shoulder goes over the other shoulder can eliminate the need to excessively abduct while simultaneously allowing for a topspin component.

All pros in the archive do the cartweel action somewhat "some more than others"

Dementieva uses it the least, which has a negative effect on her topspin component. She has a notoriously inconsistent serve for tour standards. Whereas Safin seems to be one of the most "tilted" of the top men. As well as one with one of the best ace to double fault ratios.
Compare the "tilt" of the trunks at the same moment below.

I'm pretty sure Dementieva's serve has been singled out by most coaches as the worst of the top women.

Anyway, unless you are satisfied with slice only (minimum net clearance and no heaviness) I wouldn't recommend tossing the ball way to the right.

I really think this subject needs more attention than it's been given.

[gzhpcu]

Bruce Eliott brings up cartwheeling on the service motion in his "Power Serve" article, saying all good servers do it, but as you say, otherwise not too much emphasis seems to have been placed on it, especially the benefit of avoiding rotor cuff injuries. Maybe John could have someone write up more on it in the biomechanics section...

[johnyandell]

Eric,

Can you explain exactly what you mean by "abduction" and relate it to the jpegs? Think that will really help. If you send me the URL I can actually insert the movies.

Your point about technique varying on the kick serve is very interesting. It can't be that all the pros are doing it wrong and are destined for shoulder surgery. Why don't you also take a look at Goran--another guy with a torn up shoulder and see what you see there. Again you can send me a URL.

John

[gzhpcu]

Vic Braden has been promoting tossing the ball to the right, so as to avoid having rotor cuff injuries. But in his serve video, he doesn't show cartwheeling. He shows the body upright (shoulders with little slant) and then the upper arm heavily angled to the shoulders, pointing upwards (almost 90 degrees), which places stress on the joint. He then says to place the ball to the right, so that the upper arm is not pointing up, but to the side at an angle.

However, cartwheeling gets around this problem as well. Sampras not only cartwheels, but has a body lean to the left on his serve. Eric is right: it is a question of teaching the correct technique.

[EricMatuszewski]

Here are Jpegs of simple abduction.

In lay terms it is simply the lifting the arm to the side.

I've included 3jpegs

from top.

Abducted into the (danger zone), Abducted to 90 degrees and not abducted (adducted)

Advice in World Class Tennis (Roetert), has suggested that 100degrees is the safety line.

[EricMatuszewski]

The Goran clips were too far away to make any worthwile comments (I'd really be just guessing from those).

However, Richard Krajicek withdrew from his semi-final match at the Aus Open in 1992 with a shoulder injury.

he was definitelly more towards the danger zone as far as abduction goes (according to these jpegs). However, Rafter still outdoes him though. Which is probably why Richard didn't get a tear but Rafter did.

Realize that genetics (the shape of the acromion of your scapula) also plays a part in how far you can safetly abduct while internally rotating without causing a problem. So it is possible that some are more lucky than others.

However I would think it wise to err on the side of caution here and simply train players to keep that elbow on the "safety line" exibited by Safin in the above post.

Also, players tend to abduct to the same degree on both serves (first and second) thus, I believe that the "kick" serve is unjustly singled out.

Spinal hyperextension also seems to be equal for any given player on first and second serves, but I don't want to digress right now from the question of upper extremity safety.

Here are the Krajichek stills, bet you can't guess which one is a second or which is a first serve:

[EricMatuszewski]

Phil,

If Braden was teaching people to kick serve the way your describing (with extreme abduction) it's no wonder he needed people to sign waivers!

Braden is a smart guy who's done alot to take the sport in a more scientific direction. I respect him alot for this. So, I'm really suprised by your story, as I would think that he would have been one of the first guys to see this.

Unless you "cartwheel" you have to abduct extreemely to have your arm pointing up at contact. It's important that coaches can demonstrate this correctly as people learn from what you do, much more than from what you say.

And if you can't demo it because of physical limitations, you can always show video to your students like Sampras's coach did for him of Laver when pete was a little kid.

Also realize that, if you can't demo it correctly, it's probably best not to demo it at all, as kids absorb things visually very easily.

[gzhpcu]

This clip of Safin really shows him cartwheeling:

Safin

[stroke]

Eric,

This is a very interesting thread. It does seem clear that Safin may be close to a technically perfect model for "cartwheeling" with his service motion. It is clear to me his shoulders are closer to being completely vertical than Rafter or Roddick. He is probably at about an 80 degree angle. Another thing I did notice in the still shots of the 3 players, Safin is a little closer to contact, or a little farther out of his service drop. His hitting forearm is being extended, where as Rafter's and Roddick's are still at a 90 degree angle(to the court) or more. I don't know where this makes a difference at all toward your hypothesis concerning shoulder safety.

[EricMatuszewski]

Stroke,

quote (Safin is a little closer to contact, or a little farther out of his service drop. His hitting forearm is being extended, where as Rafter's and Roddick's are still at a 90 degree angle(to the court) or more) unquote.

Good observation!

The safin frame in the first post is one frame ahead of the other two in regards to forearm extension. I've just updated the first post to include the frame before this one, where his elbow is closer to 90 deg.

As for Safin's cartweel being more vertical, i agree with you guys that it's one of the most vertical I've seen. I think it does protect his shoulder. However, the spine must be strong and flexable to be able to handle this.
I recommend stretching "Upward facing Dog" and strength excercises "Hyperextensions".

I've had this conversation with alot of top researchers in the field. Fortunately this forum allows me to show this idea much more clearly because of the attachment option.

Thanks to John we may be able to help alot of people with this.

Eric

[stroke]

Eric,

Thanks for the updated pics. That undoubtebly makes it clear that Safin does indeed have a noticeably more vertical shoulder plain position on his service motion. I agree with what you said that it contributes to Safin's extrodinary consistentcy with his serve. I was just watching him play yesterday(on the Tennis Channel) at the Madrid Masters tournament going on this week. He is having a great week and his serve is a real weapon, but as we all know, he has really no physical deficiency in his game. The commentators pointed out what a simple, beautiful service motion he has.

[stroke]

One more thing I wanted to say, Phil, I think you are spot on with your take on Vic and the kick serve. I also think Vic missed the whole "cartwheeling" thing on his serve video. In fact, his role model for his teachings, Roscoe Tanner, does this cartwheeling on Vic's video on the serve. In Vic's video, he has a computer generated stick figure of Roscoe's serve, and it clearly shows Roscoe's shoulder over shoulder rotation. Vic just does not mention it. As we all know, he does emphasize his distaste for the "kick" serve and potential shoulder problems. It looks like Safin, with his effortless motion, and perfect cartwheeling, is in not danger of a shoulder iinjury. He can hit his serve all day long.

[EricMatuszewski]

I'm updating the original jpegs once again. I'd like to thank the good folks at Apple Menlo Park for their generous help with Photoshop. Especially Nate Zyontz.

The updated jpegs include a red "Danger line". You can also use it to compare relative angle in relation to the court.