View Full Version : Ultimate discussion of pronation

03-08-2004, 06:21 PM
About 4 yrs ago, I never really understood why I would be able to see pro's inner side of string (the side that just hit the ball) right after they hit the serve.

I simply thought that they snap their wrist so much it happens. True to certain extent. But I could mainly see THAT side of string because of their standing in angle. (Think of your stance, you don't stand facing straigt to the other side)

Then I heard the term "pronation", started wondering what it really meant, if it was really different from wrist snap, and if I was "pronating".

It took me a really long time to figure it out (thanks to my slow brain).

First, let's define pronation. It's a very simple action of your hand (palm) turning inside out. Notice, you CANNOT pronate your hand without pronating your forearm. So there really is no such thing as "wrist pronation" or "forearm pronation". There is "wrist and forearm pronation" When you are in backscratch position, buttcap is pointing towards sky. As you swing UP for the ball, your racket face will start to open up. This opening is due to pronation. You can still pronate even though you don't go up for the ball AS MUCH, but won't be a great serve.

Second, Pronation in different serves.

The rate of open is prett early for the flat serve. You cannot possibly hit flat serve with closed racket face. I know flat serve has SOME spin. But the whole purpose of flat serve is to hit it "with less spin", and "more penetrating".

On slice serve, pronation happens much late. If you think logically, you want to hit the ball at 1,2 o'clock. So your racket face has to be a bit more closed than flat serve. Usually the pronation on slice serve happens after contact. BUT some people DO hit without pronation on slice serve. They simply carve around the ball. I have done it, I have seen people doing it. I am not sure which is more effective.

Kick serve. Pronation happens in different direction. Your swing path is pretty much sideways, and there really is not much forward swing to it. You cannot possibly hit a good kick serve if you don't swing up. Swing path is such that, when viewed from behind the server, the tip of the racket will draw an arch. I think pronation happens earliest in kick serve. Follow through of kick serve can be deceiving.

Agassi doesn't look like he pronates on kick serve, if you look at his follow through. And you see Sampras, he obviously pronates.
I think it's just different way of follow throughing.

Some people say that hitting at 1:00 on the ball will give you kick. I agree, I have done it, and I know a guy who does it as well. I don't know how much improvement you can make with that motion. But some of my best kick serve came from pronating.

Pronating and wrist snap.
These are two separate motion, at least in my opinion. People hitting slice/kick serve without pronation are still using their wrist, intentionally or unintentionally. Some people would argue that "carving around action" on slice serve is still a wrist snap. Some people will argue that wrist doesn't SNAP from reading tennisone article a long time ago. But I am sure you have seen pics of pro's snapped wrist after serve.

But when you are pronating, i think you serve becomes "heavier"
There are mutilple actions leading upto "wrist snap". I think main factor is hip strectch. Entire body is like a bent pole. And if you have something loose attached on the top, it's going to "SNAP forward/downward" after you let the bent pole go. B Bill can probably explain this much better.

So my conclusion is that you can still hit serve without pronation NOT on flat serve. And pronation is seperate motion from wrist snap. I think it's sometimes too difficult to pay too much attention to too little things. Instead of forcing pronation, concetrate on hitting the ball squre with loose arm and grip while you keep your head up. If you keep your grip loose, and have a decent motion, then wrist snap will happen naturally.

I once asked Taylor Dent (atptour.com), about wrist snap and pronation. His reply was that he doesn't like to get into too much technical. And he thinks that loose arm and timing are the most important part.

03-09-2004, 04:47 AM
Not to make this any more complecated, here are my random thoughts and observations on this subject:

-You CAN serve flat serves without forearm pronation. I used to do that basically using throwing motion and I was clocked at 118 mph before injured my shoulder

-You CAN serve slice, topspin, and kick serves without forearm pronation. You see many local players do it. I can still do it if I want to. Your observation of Agassi's serve is a correct one. He doesn't seem to pronate his forearm. Old footage of Chris Evert shows that she doesn't either. However, most outstanding servers do pronate nowadays.

-Many good players practice different degrees of pronation without knowing. I work with a Barcelona trained player who used to be ranked in 200s in the world on a regular basis. He thinks I am crazy when I ask him about pronation and refuses to even discuss on this subject any further with me. He can crack 120mph serves on a regular basis without any apparent pronation. Yet, when I video taped him and analysed his service motion on slow motion, he does pronate on both flat and kick serves but not so actively. He says he does close the racket head and turn his forearm so he can finish on his left side without hitting himself. I think, like Taylor Dent, he knows what the right motion feels like and doesn't get too technical. He does say to serve with just lose arm and hit it. Well, actually, that is what he does and he can put some serious heat every time without much fuss. It is kinda funny because I can throw a tennis ball twice as far as he can, but he got his serving motion down like nobody's business from years of practice. The important thing is that he does not actively try to force the forearm pronation and finish on the right side like Graf or Becker. What I am trying to convey here is that there are different degrees of pronation and you may not have to consciously try to pronate to achieve a good serving motion. There are players like Agassi who doesn't seem to pronate much at all and there are players like Graf who actually pronate so much and so actively she finishes on the right side even on a flat serve. Many other players fall somewhere in between these too extremes.

-I have tried to look for books that discuss on this subject but I have not found any. All books that I have looked at had old 70s and 80s techniques. Some books that were originally written in Germany had some new techniques but not much on serves that utilize the forearm pronation nor the new topspin forehand technique (the Ferrero forehand). This is really strange because Boris Becker, Steffi Graf, and Pete Sampras started using this seemingly new technique 15+ years ago.

03-09-2004, 05:11 AM
i think discussion of pronation in serve should be limited to the moment of ball impact (or the very short duration between right before and right after the impact), coz otherwise the meaning gets too broad and a little bit out of focus. what i'm still wondering is whether guys saying they pronate on kick serves really see their back of the hand right at the moment of ball impact. i suspect you see (if you try) half palm half side of the hand (sign of an ongoing supination) on a normal kick serve impact while you see 80% side 20% back of the hand (sign of an ongoing pronation) on a flat serve impact. if not, we are talking about different things under the same titles... and i may be wrong

Bungalo Bill
03-09-2004, 08:10 AM
I have always said, that this is something that should happen naturally. YOu should not force pronation as this could lead to a shortened career in tennis. Here is a study on this very issue:
Beware of Pronation!

The information you are about to read is currently the subject of an interesting debate among some of the world's leading tennis biomechanists and physiologists, including some not cited in this article. Individual interpretation of this information is still ongoing, and the USHSTCA does not present this article as a final answer to the question However, Dr. Groppel's concerns about the cause of shoulder injuries in junior players should be seriously considered.

One of the greatest breakthroughs in tennis teaching in the last 20 years was the discovery of pronation, the outward turn of the forearm, wrist and palm at the end of the service motion that happened so quickly, most observers could not see it.

For many years, tennis teachers told their students to "snap your wrist", which was misconstrued to mean the snapping down and inward of the hand instead of the upward and outward turn. Today, many teachers now say, "high-five" the ball.

The discovery and teaching of pronation and the power it contributes to the serve because of its place at the end of the kinetic chain has not been all positive, however, according to noted biomechanist, Dr. Jack Groppel.

Dr. Groppel believes that an over-emphasis on pronation by teachers and coaches who are accenting this part of the kinetic chain out of proportion to its importance is leading to a dramatic number of shoulder and arm problems, and a scientific study may bear his theory out.

Dr. Bruce Elliot of the University of Western Australia is highly-regarded worldwide for his work on tennis biomechanics and has been a pioneer in the effort to determine what each link in the kinetic chain contributes to overall power.

According to Dr. Elliot and his associates on upper limb segments only, forearm pronation contributed only 5.2% of overall speed on a serve! In essence, there is little or no wrist movement on the serve, forearm pronation causes the hand to turn outward, which means all the hand can do is flex at the finish of the serve.

This article continues with surprising information on how little pronation actually contributes to racquet head speed, where most power on the serve actually comes from, and why emphasizing pronation may lead to injury.

Also, here is a link that shows how the racquet should be back to have correct pronation in the serve. I am using the following as an illustration because I couldnt find anything else that showed it.


03-09-2004, 10:56 AM
Thanks for the article, mr. Bungalo

While it is an interesting article, it doesn't seem to conclusively say or provide any substantiated evidence that pronating is bad for shoulder or arm health and responsible for all the increased occurances of injuries.

The reason for the interest on this subject, at least to me, there is much confusion about this especially at club tennis level where many players are getting many conflicting advices from club pros as to:

1. how one should grip the racket
2. how one should meet the ball
3. how one should follow through

Of course, there will be some variances depending on an individual, but I would like to what is the right way to execute this new (now 20-year-old) technique. Is this the way to serve in the 21st century or is this like using traditional stroke vs. topspin w. western grip where it is a matter of a personal preference?

Well, to me at least, I find that 5.2% figure confusing and misleading, and I personally doubt that Sampras would have been as effective in serving if he did not have an very pronounced pronation on his serves. Please tell me if I am wrong, but from my experience, pronating provides the following benefits:

1. Better disguise (you can vary spin and placement with the same toss)
2. Biomechanically more sound vs. old wrist snap technique (you get to use bigger and stronger muscles and put less stress on weak mucscles and joints) and therefore is safer for shoulder
3. Better spin and consistency (depending on your toss, you can put topsin even on flat serves and because you don't flex with your wrist/hand at the moment of impact, it is more consistent some what like putting in golf)

Bungalo Bill
03-09-2004, 11:16 AM
I dont think your wrong at all. I think you will have a point no matter what you say. I agree with you too!

However, I am concerned with injuries. I have never had a problem with my serve (unless of course I am out of shape) and I have never concentrated on pronation on my serve. I am of the camp that this happens naturally (and it does) and not everyone is blessed with the genes of Sampras.

I think what you listed (especially #2) the article and link was supporting.

The 5.2% means that it doesnt add significant power to justify the risk for injury. So you dont need to force pronation. Just make contact on the ball where your suppose to toi generate your spin.

However, with that said, I agree with you as well! Just understand the dynamics of doing this that there is opposing views to this and there is documentation that supports the potential of injury taking place that can have an impact on your enjoyment of this game.

03-09-2004, 11:31 AM
Mr. Bungalo,

I agree with you that if one focuses too much on the forearm pronation and not allow the flexibility and strength to develop in using this new technique, it may lead to shoulder injuries.

I am not out to prove anybody's theory wrong, but I would just like to get some good answers on this, because all my previous coaches thought I was high on something whenever I asked them about that Sampras' "Tourna Grip" picture and why it looks so much different than what we have been taught.

03-09-2004, 12:45 PM
I really don't see how you would serve flat without pronation. It's just logically impossible. To hit flat serve, you HAVE TO meet the ball square. If you have continental, and hit flat serve, there is no way you will meet the ball square unless you pronate.

I have literally seen EVERY serve of EVERY pro on tennisone.com, going by frame by frame. I have not seen ony guy without pronation and going down the middle on the deuce (which most likely to be flat).

Pronation is such a natural action. People can serve flat with continental and still not know about it. It just happens so naturally and at such a instant moment, you won't even be able to observe it.

I don't think you can have good serve, trying to FORCE pronation. The degree of pronation would happen naturally. I don't think Boris or Graf TRIED to pronate excessively. It probably was a result of loose arm and what they are trying to do to the ball.

IF you see some of kick serves hit by Sampras on tennisone.com, you can probably see his back of hand if you were standing behind him.

I have always doubt researches done on wrist action on serve. Andy Roddick once said he couldn't hit spin serves because his wrist was sore, and couldn't use wrist on the serve. I can probably still dig out that interview. Goran also said about Sampras hits serve with a lot of wrist action...

I think another overlooked aspect of serve is backscratch position. I think as long as you go into back scratch position early enough, you are going to hit in reasonable good motion.

Bungalo Bill
03-09-2004, 12:57 PM

When it comes to pictures, pictures can be very decieving whether something is being forced or is happening naturally. No question, Sampras has tremendous racquet head speed and with a relaxed arm it can appear he is forcing it. Much like the arm of a pitcher that looks as if his arm is going to come off when he pitches on certain photos.

I think you have a great point Thunnus. I dont know if you will find your answer on this one, as research is still coming in on this. My belief is that if anything is forced it has to have consequences. I never sided with the wristiness of Agassi and caught a lot of flack because of it. I was "old school" teaching fixed wrist, etc! LOL

But films dont lie, and now we are seeing high speed film (although still to slow) that captures more of a pro's movement.

I think you would agree that tennis is a fluid sport. The more fluid you are in your movement and relaxed the better.

Again, I think you are right on in questioning this aspect of the game. When coaches do not do proper research, many of them jump to conclusions and use what they can see with their eyes as the result of a good stroke. They do not do enough research and ask questions such as yourself.

03-09-2004, 02:43 PM

It is easy to hit flat serves without pronation. I think the difference is that you snap your wrist instead of forearm AFTER you hit the ball which would result in your right thumb pointing at 9 o'clock instead of 6 as you follow through. This is the same as the throwing motion. Read the article above on this and put two and two together. The idea of forearm pronation is a new one and for many years people didn't do it naturally. I was a pitcher when I was young and I was told by my coach and many books at that time that I should serve like throwing a ball or racket.

Also, if you watch Graf serve very carefully on slow motion, you will see that she her arm almost stops on her right side after making the contact with her forearm fully extended and pronated with her thumb pointing at 6 o'clock. She then drops her racket to get it out of the way. If you watch the Aussie Open final 1988 vs. Chris Evert, you will see this as Cliff Drysdale compares her serve motion with Evert's side by side. My naive guess is that Germans were one of first ones to pick up on the benefit of pronation and trained their youngsters. I have no facts to support it, it is just my gut feeling since they seem more scientific on this sort of stuff.

As for active pronation, I agree that smooth fruid motion provides the best power and consistency in tennis. But for now, because I have done my serve without it for so long, I must consciously do it until it becomes a second nature for me. Also, I find that I need to pronate more for spin serves. Because I like to toss to 12 o'clock vs. 1 o'clock anyway, my first serve has a bit of topspin naturally which made my first serve percent to go from 40-50% to 60-70%.

Again, I am a curious type of guy and I imagine this issue of pronation is very similar to the last stage of the golf swing where there are lots of debates as to whether you should provide additional whip through the impact with your forearm and this causes two forearms to get crossed. Of course, some argue that this should happen naturally. After devoting an entire summer studying this and hitting tens of thousands of balls, I figured out that it was both. Everything slowed down and I could feel precisely how much I could delay that whip and whip it through just right in a fluid motion. My guess is that pronating in serve is somewhat like that. It is an additional accerelation that you provide on the last kenetic chain but you do it at just right moment and so fluidly, it feels like it was a part of natural swing.