Poll: The Wrist Snap; autonomic or deliberate

[pvaudio]

^ These are the most important words in this thread. This is a real role of pronation at serves - it is not a source of additional power nor rotation (perfectly opposite to forehands, what leads to misconceptions). It's role is just turning racquet's head, nothing more.

This is a consequence of specific orientation of the plane of racquet's head. In the early phase of stroke, axis of forearm and racquet's head are in the same plane, so you have to turn racquet's head to hit the ball with strings.

The most horrible misconception at serves is that pronation at serves is a source of additional energy. That's totally not true. But it is true that without pronation you are unable to increase energy at impact.

Is it a contradiction?

No, just physics and biomechanics. It's easier to increase speed of racquet's head if you hold the racquet as a hammer - and that's what proffesional players do. But if you accelerate in this way, you have to turn your racquet's head just before stroke. This is where pronation comes on the stage.

So, once again: pronation at serves is not a source of additional energy, but it is a method which guarantees the higher efficiency of other muscles.

No, I'm afraid that this is not true. The pronation through the arm swing results in a large increase in racquet head acceleration. I can stand on the baseline with my racquet up, toss the ball and just snap the ball down into the box at a higher pace than most people at my level even serve with their full motion. Why? Because it's the one stroke I needed to have down solid since I used to be very large and couldn't handle long points due to endurance.

So no, I'm afraid that you're wrong for your own reasons. It's a problem of angular momentum: flexion of the pronator muscles results in a rapid acceleration of anything attached to the hand. The flexion of the pronator muscles causes the torque that carries the racquet head through the serve. That's why it is possible for players to just stand there and hit arm only serves faster than most and it's because they have figured out the mechanics of the wrist snap to their fullest potential. You can't arm a serve faster than you can snap a serve in. No matter how hard you try, it just isn't possible.

 

[pvaudio]

Oh and before you say something along the lines of "my science trumps your experience", I am studying engineering and as a consequence have had my fair share of physics from basic mechanics of sliding blocks up incline planes to special relativity and quantum mechanics. That plus having had my fair share of anatomy and physiology courses along with one specifically targeted at sports kinesiology, I would say that I am fairly educated on everything that you are saying.

 

[Counter]

Terminology...

I thought pronation and wrist snap are two different things

Exactly, that's what I thought. Then again, I know what pronation is, but I'm not so sure what people mean by a "wrist snap". Presumably, that term refers to flexion of the hand (perhaps combined with a degree of deviation).
Anyway, to equate the "wrist snap" with "pronation" seems just plain wrong, for all I know (which admittedly is not too much), and this may be the cause of some of the apparent confusion in this and similar threads.

 

[GuyClinch]

^^^It might be wrong but athletes like James Blake don't distinguish between pronation and wrist snap (flexion). Its used interchangeably. Some coaches - do distinguish but not all. When they ask you to "snap" the ball down into the court they want you to pronate more. Rather then get caught up in this semantic argument - which sidetracks too many threads the point is the pronation adds signficant power to the serve. Does flexion add power as well? It might but its not significant IMHO.

Anyway just because you don't have to really think about it once you get the motion down doesn't mean the muscles don't fire. If you numbed down those muscles you would have a hard time serving at all.. Or if you replaced your upper arm with a device that could attach to a tennis racquet and something that would allow passive rotation around the elbow would you serve as well? I really doubt it..

 

[gzhpcu]

Seems to me that what we want is to maximize racket speed. More racket speed means more mass x acceleration, means more ball speed. The forearm pronation just prior to impact causes the racket to move in an arc of about 180 degrees, from being on edge pointing inward and backwards to the racket pointing forward and the face outward and then the racket going down after impact. If you didn't have this range of motion, the racket would be moving less fast.

 

[tricky]

Note that we're ignoring the movement of the upper arm and shoulder, which provides the majority of the power and accelerates a lot during the last 1/3 of the service movement. The upper arm rotates around its axis. From a tilted position, this helps to facilitate a "pronation phase" of the serve.

As for forearm pronation, by itself, does not contribute that much to racquet speed. But forearm pronation and radial deviation together, with the tilt from the torso, gives you passive wrist movement. And that passive wrist movement is where that 15-30% of racquet power comes from.

Because forearm pronation pre-empts both the passive wrist flexion and the active radial deviation, pronating or rotating around the forearm does lead to wrist flexion. And this goes to the clock visualization and whether you intend to hit balls flat, extra topspin, slice, etc. All that affects the racquet speed as well.

If I understand him correctly he has found that there is definitely some active use or contraction of the muscles in the forward wrist motion. So the wrist movement is not all passive, and may even qualify as some form of "snap."

Yeah, this bit surprised me. I've read Brian's articles, which I believe were published after Yandell's article, and at that point his position was that wrist flexion was a passive/motion dependent effect.

Now, having said that, some of the analysis does validate that the wrist muscle do actively contract, but they may be the wrist extensors. The wrist extensors aid in abduction, which translates to radial deviation. I think it's possible for active pronation and active wrist flexion to occur at the same time, but I suspect that they severely inhibit each other. Whereas, active pronation and active radial deviation work together. This is a natural part of groundstrokes as well as serves.

 

[sennoc]

The pronation through the arm swing results in a large increase in racquet head acceleration.

How, physically? I do not believe in fairy tales, so explain it to me, how is it possible to significantly increase energy from pronation at almost straight hand. Don't talk about great trainers, famous players, your education, just use knowledge and logic and explain it to me.

I can stand on the baseline with my racquet up, toss the ball and just snap the ball down into the box at a higher pace than most people at my level even serve with their full motion.

I'm not interested in what you "can" nor what you think you do. These days most players do not know what they do. Top ATP players know so much about physics that without a good trainer they are unable to improve. Roddick "can" hit the fastest serves in the world. Ask him for explanation how does he hit his famous serves. I can't wait to read his scientific arguments...

Oh and before you say something along the lines of "my science trumps your experience", I am studying engineering and as a consequence have had my fair share of physics from basic mechanics of sliding blocks up incline planes to special relativity and quantum mechanics. That plus having had my fair share of anatomy and physiology courses along with one specifically targeted at sports kinesiology, I would say that I am fairly educated on everything that you are saying.

Wow, so great!

If GuyClinch is unable to do that, maybe you will be able to answer my very simple quetions from previous posts? Or should I just believe in your education?

 

[gzhpcu]

I think Will explains the effect of pronation on racket speed quite well here:

http://www.fuzzyyellowballs.com/video-tennis-lessons/serve/serve-fundamentals/pronating-on-your-serve/

 

[theZig]

It's not a deliberate snap of the wrist, but deliberate actions which lead to the snap. my two cents

 

[sennoc]

Will does really great job, I often use his slo-mo movies too, they are amazing source of knowledge. Unfortunately, at this point Will makes mistake.

 

[GuyClinch]

If GuyClinch is unable to do that, maybe you will be able to answer my very simple quetions from previous posts? Or should I just believe in your education?

No one understands your questions dude. Is English your second language? If you want to know why your lower to upper arm angle on a good serve isn't a straight line - its because that doesn't maximize pronation. The serve doctor explains this..

Its not 90 degrees either (which I think you suggested) because you would lose too much leverage from the length of your arm. So people kind of split the difference. You can easily see this on Pete Sampras serves but all the pro servers do this. I imagine with the right equations you could calculate the PERFECT arm angles such that force is maximized. But in practice I am sure most servers work this out for themselves. (And this would probably vary exactly depending on motion and build of the server).

Anyway IF your theory about pronation not being a "power source" was correct a "pancake" serve would be much much more effective. Most pancake servers (which just use one lever) can hit around 90mph (the very best ones). But by switching to the continental grip and taping into the power that can be afforded with the second lever people can hit those huge 120mph + serves. Yeah some of that is lower wind resistance (from the L shaped start) but I don't think its THAT significant.

Like i said even stubborn people like you who deny the fact that these muscles actively fire - would find greatly diminished serves if those muscles were injured or shut down..

Anyway none of this is my idea - its all been established by various pros and research. You just ignore the words of top coaches AND pros. But hey if you want to be stubborn you can claim victory. Your just so closed minded you don't want to consider any other point of view..

As I said way earlier - people do actively fire those muscles. That's why commands like "pronate more" or 'snap that ball onto the court more" can actually WORK for players.. It's why pro coaches will teach the serve backwards - from the pronation.. And then add in the other power sources.. Shoulder..then chest and leg drive etc.

Pete

 

[drakulie]

This is a real role of pronation at serves - it is not a source of additional power nor rotation (perfectly opposite to forehands, what leads to misconceptions). It's role is just turning racquet's head, nothing more.

wrong. Prontaion is what guarantees additional power.

Here is a breakdown of the Sampras Serve. As you could see, during the pronation phase, his racquet head speed increases from roughly 50 mph to 113 mph.

http://www.tennisserver.com/set/set_03_11.html

 

[sennoc]

wrong. Prontaion is what guarantees additional power.

Here is a breakdown of the Sampras Serve. As you could see, during the pronation phase, his racquet head speed increases from roughly 50 mph to 113 mph.

I'm a little bored talking about nothing with GuyClinch, so let's analyze your image. It is really interesting. More for me than you, I'm afraid

As you said, we see that there is a huge increase in speed of racquet's head: 50 to 112 mph. Wow, Sampras was good (was he sufficiently good for you, GuyClinch?).

You say that's because of pronation.

I say your interpretation of data is wrong, because you see not what really exists, but what you want to see.

Numbers are nothing, are just numbers. What's important is physical meaning of numbers. Let's compare phases of Sampras serve with your numbers.

Check this image, first frame:

It is clearly visible that there is no pronation at all - at this moment Sampras just starts to pronate.

Compare this with your image. First frame on my image is close to point 103 on yours - and this is the moment when Sampras starts to pronate.

So, we have 50 mph at the beginning, then 103 mph, then Sampras starts to pronate and then you have 112 mph at contact. Sampras' speed in pronation phase has increased by 9 mph.

Does it mean that +9 mph is by pronation? Probably not, because forearm is not the only part of kinematic chain at work at this moment. So, it is safe to say that pronation adds less than 9 mph to his 112 mph serve - significantly less than 10%.

Seeing is not the same as understanding, man. You have to be very careful at interpretation of data.

 

[drakulie]

So, we have 50 mph at the beginning, then 103 mph, then Sampras starts to pronate and then you have 112 mph at contact. Sampras' speed in pronation phase has increased by 9 mph.

Wrong. Sampras begins the act of "pronation" on the very first photo in the sequence you provided. He is finally in a "prone" position at impact (113 mph) second photo. Therefore, by "pronating" he has gone from 50 to 113 mph racquet head speed. In the 3rd, 4th, 5th, and 6th photos, he is passed a "prone" position, and the ball has already been struck, so anything he does at this point is insignificant to ball speed and or energy.

In the following video, Roddick begins to pronate at the 4 second mark. He is in the "prone" position and has fully pronated by the time he makes impact with the ball (9 seconds).

In the sceond sequence, he is in a prone position at the 16 second mark. Therefore, has already "pronated", which results with all that energy being delivered to the ball.

In the third sequence, he begins the act of pronation around the 41 second mark.

http://www.youtube.com/watch?v=SZbxKuLEP_o

 

[pvaudio]

I'm a little bored talking about nothing with GuyClinch, so let's analyze your image. It is really interesting. More for me than you, I'm afraid

As you said, we see that there is a huge increase in speed of racquet's head: 50 to 112 mph. Wow, Sampras was good (was he sufficiently good for you, GuyClinch?).

You say that's because of pronation.

I say your interpretation of data is wrong, because you see not what really exists, but what you want to see.

Numbers are nothing, are just numbers. What's important is physical meaning of numbers. Let's compare phases of Sampras serve with your numbers.

Check this image, first frame:

It is clearly visible that there is no pronation at all - at this moment Sampras just starts to pronate.

Compare this with your image. First frame on my image is close to point 103 on yours - and this is the moment when Sampras starts to pronate.

So, we have 50 mph at the beginning, then 103 mph, then Sampras starts to pronate and then you have 112 mph at contact. Sampras' speed in pronation phase has increased by 9 mph.

Does it mean that +9 mph is by pronation? Probably not, because forearm is not the only part of kinematic chain at work at this moment. So, it is safe to say that pronation adds less than 9 mph to his 112 mph serve - significantly less than 10%.

Seeing is not the same as understanding, man. You have to be very careful at interpretation of data.

My God man, you haven't the faintest idea as to what you're talking about. I suggest that you take a class in kinesiology before continuing to talking about this since you clearly don't understand biomechanics.

 

[sennoc]

My God man, you haven't the faintest idea as to what you're talking about. I suggest that you take a class in kinesiology before continuing to talking about this since you clearly don't understand biomechanics.

Empty words. Show me my mistakes. What's wrong with this analysis - except the fact you don't agree with it?

Oh, I forgot. You are well educated. So, some quotes for you:

"Pronation of forearm does not give power but realigns the racquet face"
(Biomechanical principles for the serve in tennis, ITF Coaches Education Programme)

"The purpose of this study was to measure the contributions of the motions of body segments and joints to racquet head speed during the tennis serve. (...) Forearm pronation made a brief negative contribution."
(Contributions of joint rotations to racquet speed in the tennis serve, Journal of Sports Sciences)

This method showed that in the tennis serve the greates contribution to final speed of racqet head was upper arm internal rotation (29%), followed by wrist flexion (25%), upper arm horizontal adduction (23%), forearm pronation (14%) and forward movement of the shoulder (5).
(Science and Racket Sports IV, about Springings et al. 1994)

Approximate Contributions to Impact Racquet Velocity (%):
Shoulder: 10
Horizontal Flexion: 15
Internal Rotation : 40
Forearm Extension: 0
Pronation: 5
Hand Flexion (palm): 30
Radial/ulnar flexion: 0

(Bruce Elliott et al.,1995)

Approximate contributions to impact racquet velocity (%), Power serve
Shoulder: 10
Upper arm
- Horizontal flexion: 15
- Internal rotation: 40
Forearm
- Extension: Negligible
- Pronation: 5
Hand
- Flexion (palm/ulnar): 30
- Flexion (palmar/radial): –

(Biomechanics and tennis, B. Elliot, Br. J. Sports Med. 2006)

Maybe you should go back to the school?

 

[sennoc]

Wrong. Sampras begins the act of "pronation" on the very first photo in the sequence you provided. He is finally in a "prone" position at impact (113 mph) second photo. Therefore, by "pronating" he has gone from 50 to 113 mph racquet head speed.

Read my previous post again, you haven't understood it.

 

[tricky]

"Pronation of forearm does not give power but realigns the racquet face"

This is worth noting. Because pronation manages how the racquet face opens up, it significantly influences the swing path. When you swing with different clock hands, that is where you're controlling/managing forearm pronation.

- Flexion (palm/ulnar): 30

Ah, yeah, this is also a partial reason why I'm not a big fan of isolated pronation drills. Most of them are taught where the pronation and flexion are coming from the radial/thumb side of the hand. Put that should be coming from the pinkie/ulnar side. Different muscles are used.

 

[thebuffman]

This method showed that in the tennis serve the greates contribution to final speed of racqet head was upper arm internal rotation (29%), followed by wrist flexion (25%), upper arm horizontal adduction (23%), forearm pronation (14%) and forward movement of the shoulder (5).
(Science and Racket Sports IV, about Springings et al. 1994)

whoa! sennoc that is some powerful stuff. i appreciate you introducing such a disciplined and non-accusatory argument to the thread. i am attempting to open my mind to what you are saying albeit difficult. the first thing anyone has to get through is cognitive dissonance when someone introduces a concept diametrically opposed. the typical response is defensive and then it goes to defamation, "you are just dumb and so is your point". i encourage you to continue offering an argument devoid of irrelevant emotion.

Cognitive dissonance is an uncomfortable feeling caused by holding two contradictory ideas simultaneously. The theory of cognitive dissonance proposes that people have a motivational drive to reduce dissonance by changing their attitudes, beliefs, and behaviors, or by justifying or rationalizing them.[2] It is one of the most influential and extensively studied theories in social psychology.
Dissonance occurs when a person perceives a logical inconsistency in his beliefs, when one idea implies the opposite of another.... read more

 

[thebuffman]

Ah, yeah, this is also a partial reason why I'm not a big fan of isolated pronation drills. Most of them are taught where the pronation and flexion are coming from the radial/thumb side of the hand. Put that should be coming from the pinkie/ulnar side. Different muscles are used.

dude you just said something here! i have noticed that some of my most solid "feeling" serves some when i allow more flex in the wrist and i feel the pressure against the pinkie/ulnar side of the hand. generally i tell myself, "man that felt solid, but i am not suppose to feel the pressure there...i am suppose to feel it from the thumb". perhaps i have been cheating myself.

 

[sennoc]

i am attempting to open my mind to what you are saying albeit difficult.

Nothing unusual. It took me 3 long years to understand the real role of pronation. You have 2 years and 11 months yet...

 

[thebuffman]

is anyone able to break down step by step what these terms mean?
This method showed that in the tennis serve the greates contribution to final speed of racqet head was upper arm internal rotation (29%), followed by wrist flexion (25%), upper arm horizontal adduction (23%), forearm pronation (14%) and forward movement of the shoulder (5).

like what the heck is internal arm rotation?? is that something you can even control since it is internal (inside of your body)? or is it internal meaning the inside as opposed to the outside part of the arm??? totally confused.

 

[drakulie]

Read my previous post again, you haven't understood it.

No need to. It is obvious from your post, you don't know what "pronation" means.

When the racquet is in the drop down position (aka back scratch), Sampras begins pronating his forearm as soon as he begins to bring the racquet up. As a result, he reaches the final "prone" position at contact. He is "prone" at contact".

We conclude, he is "pronating" from back scratch to contact.

Therefore, his racquet speed at the back scratch position is at 50 mph. At contact it is at 113 mph. He has increased his racquet head speed 83 mph thru the act of pronation.

 

[drakulie]

is anyone able to break down step by step what these terms mean?
This method showed that in the tennis serve the greates contribution to final speed of racqet head was upper arm internal rotation (29%), followed by wrist flexion (25%), upper arm horizontal adduction (23%), forearm pronation (14%) and forward movement of the shoulder (5).

like what the heck is internal arm rotation?? is that something you can even control since it is internal (inside of your body)? or is it internal meaning the inside as opposed to the outside part of the arm??? totally confused.

who the hell knows. It is a very lousy study if it is intended to educate.

 

[GuyClinch]

This method showed that in the tennis serve the greates contribution to final speed of racqet head was upper arm internal rotation (29%), followed by wrist flexion (25%), upper arm horizontal adduction (23%), forearm pronation (14%) and forward movement of the shoulder (5).

LMAO so wrist flexion is a big source of power?

http://www.youtube.com/watch?v=YT714mG17bA

Clearly they studied this guy. For any study to be valid we need to know the experimental method - who was studied. That kind of thing..<g> You know science 101.

 

[sennoc]

LMAO so wrist flexion is a big source of power?

http://www.youtube.com/watch?v=YT714mG17bA

Clearly they studied this guy. For any study to be valid we need to know the experimental method - who was studied. That kind of thing..<g> You know science 101.

I have no time to teach you what to do with scientific data. And, from my point of view, it's totally not important what you think about pronation. I said what I should, from my point of view discussion is finished.

 

[GuyClinch]

I have no time to teach you what to do with scientific data. And, from my point of view, it's totally not important what you think about pronation. I said what I should, from my point of view discussion is finished.

Cool story, Bro.

You lack time that's why you keep posting on this thread. Yeah get back to your busy world of pulling up studies and pretending to be educated.

My guess is what's going on with these studies (not having actually seen the study just the summaries) is that they are analyzing the actual muscle groups.

When a player "pronates" he likely uses more muscles then just the pronators in the forearm. Hence the wrist flexion, internal shoulder rotation and such - all the muscles incorporated in turning the racquet from the L position to the actual contact of the ball. (Or what we people call pronation)..

In short your trying to get off on a technicality because your wrong. If we count this..

http://www.youtube.com/watch?v=EpxF4M_bKZ4

As pronation then it adds alot of power to your serve and you have to actively do it. We can call it like McLennan says "turn of the arm" if that makes you happier.

 

[bhupaes]

Sennoc, although what you say stands everything I know on its head I concede that you may be right.

Brian Gordon has pointed out the contribution of upper arm rotation, and also that foream pronation adjusts itself to compensate for upper arm rotation. I seem to remember him asserting that the forearm may even move in the direction of supination relative to the upper arm in this process of adjustment (sorry if I mangled what Brian said, but this is what I understood from his study). This I think supports your point. I can also believe that the wrist is heavily used, and actively at that, but with flexion in the radial/ulnar sense. This will explain the number of times I've experienced wrist pain at the ulnar end, among other things... ha! But there does seem to be a kinetic link between pronation and ulnar flexion... does the act of trying to pronate aid in better flexing of the wrist in the ulnar direction? Hmm...

Edit: Forgot to add, if the last statement above is true, pronation then becomes a big contribtor to racquet head speed, albeit indirectly!

 

[tricky]

i have noticed that some of my most solid "feeling" serves some when i allow more flex in the wrist and i feel the pressure against the pinkie/ulnar side of the hand

Yes, that's correct. Usually when just going through your service motion, it helps to hold the racquet with your index, 4th, and fingers (i.e. 2-4-5), and then practice the swing. This creates a "pinkie bias" with the forearm, wrist, and hand, so when you go through the "pronation phase" of the serve. This is actually one of the subtle contradictions between the pronation phase and the overall swing motion. Pronation and radial deviation (thus passive wrist flexion) are altogether stronger with a thumb bias. But overall upper arm movement (especially internal shoulder rotation) is stronger with the muscles on the outside of the arm, which correlates with a "pinkie bias." Moreover, you have to use the "same set." Therefore, there is tradeoff between overall arm rotation and "pronation (i.e. pronation phase.) You sometimes see this issue in baseball pitching mechanical discussions, because certain schools (i.e. Dr. Mike Marshall) believes that pitching power should come more from the pronation phase rather than loading up on the shoulder.

This method showed that in the tennis serve the greates contribution to final speed of racqet head was upper arm internal rotation (29%), followed by wrist flexion (25%), upper arm horizontal adduction (23%), forearm pronation (14%) and forward movement of the shoulder (5).

Internal rotation: Overall "overhand throwing" movement of the upper arm

Upper arm horizontal adduction: Upward movement of swing from racquet drop and the "dunking" motion of the swing during the pronation phase.

Wrist flexion: This is when the racquet head starts "slamming down" past the elbow when the racquet has reached its height.

Forearm pronation: When the racquet face is opened up for the ball

Forearm movement of shoulder: Ehh, this is neglible in terms of power and more associated with your overall follow-through. As you follow through, your right shoulder comes out in front. That's about it.

 

[tricky]

But there does seem to be a kinetic link between pronation and ulnar flexion... does the act of trying to pronate aid in better flexing of the wrist in the ulnar direction? Hmm...

Yes. The idea goes that due to the combination of three things:

1) Overall "tilted" motion of the body/arm
2) Active forearm pronation
3) Active deviation of the hand (or hand wiping toward the thumb side)

The wrist flexes forward. Maybe it does this actively, but I'm still skeptical. In any case, all three conditions must be met for the wrist flexion to happen naturally and significantly.

 

[bhupaes]

Yes. The idea goes that due to the combination of three things:

1) Overall "tilted" motion of the body/arm
2) Active forearm pronation
3) Active deviation of the hand (or hand wiping toward the thumb side)

The wrist flexes forward. Maybe it does this actively, but I'm still skeptical. In any case, all three conditions must be met for the wrist flexion to happen naturally and significantly.

Another question, tricky: One of the popular tips is to hold the racquet so that the pinky hangs below the racquet butt (for serves), and grip mainly with the thumb and forefinger. But I see that many pros have their full hands on the racquet, including the pinky. I guess it makes sense to have the pinky on the racquet (close to the edge of the butt of course) in light of the role of pinky-bias? Can additional leverage be gained this way? Thanks again for the great insight into this process!

 

[tricky]

One of the popular tips is to hold the racquet so that the pinky hangs below the racquet butt (for serves), and grip mainly with the thumb and forefinger.

And that one I don't care for too much. You'll get great pronation, but you may notice that you'll feel a lot of your biceps and inner part of forearm in your service motion.

 

[pvaudio]

Empty words. Show me my mistakes. What's wrong with this analysis - except the fact you don't agree with it?

Oh, I forgot. You are well educated. So, some quotes for you:

"Pronation of forearm does not give power but realigns the racquet face"
(Biomechanical principles for the serve in tennis, ITF Coaches Education Programme)

"The purpose of this study was to measure the contributions of the motions of body segments and joints to racquet head speed during the tennis serve. (...) Forearm pronation made a brief negative contribution."
(Contributions of joint rotations to racquet speed in the tennis serve, Journal of Sports Sciences)

This method showed that in the tennis serve the greates contribution to final speed of racqet head was upper arm internal rotation (29%), followed by wrist flexion (25%), upper arm horizontal adduction (23%), forearm pronation (14%) and forward movement of the shoulder (5).
(Science and Racket Sports IV, about Springings et al. 1994)

Approximate Contributions to Impact Racquet Velocity (%):
Shoulder: 10
Horizontal Flexion: 15
Internal Rotation : 40
Forearm Extension: 0
Pronation: 5
Hand Flexion (palm): 30
Radial/ulnar flexion: 0

(Bruce Elliott et al.,1995)

Approximate contributions to impact racquet velocity (%), Power serve
Shoulder: 10
Upper arm
- Horizontal flexion: 15
- Internal rotation: 40
Forearm
- Extension: Negligible
- Pronation: 5
Hand
- Flexion (palm/ulnar): 30
- Flexion (palmar/radial): –

(Biomechanics and tennis, B. Elliot, Br. J. Sports Med. 2006)

Maybe you should go back to the school?

Let me see the actual data, because some of the things in here are just blatant garbage and have no bearing on your argument. Wrist flexion creates no power whatsoever. The "wrist muscles" that you're talking about also include the pronator muscles, which when flexed, pronate the hand. So where exactly are you going with this? You posted something riddled with typographical errors, without posting the actual method, procedure or conclusions, and even after you did that, your own articles are proving you wrong.

 

[pvaudio]

Another question, tricky: One of the popular tips is to hold the racquet so that the pinky hangs below the racquet butt (for serves), and grip mainly with the thumb and forefinger. But I see that many pros have their full hands on the racquet, including the pinky. I guess it makes sense to have the pinky on the racquet (close to the edge of the butt of course) in light of the role of pinky-bias? Can additional leverage be gained this way? Thanks again for the great insight into this process!

Unless you're a very accomplished server, don't do it. You'll end up squeezing the racquet very tightly to compensate thus putting unnecessary wear on your biceps.

edit: Beaten!

 

[tricky]

Let me see the actual data, because some of the things in here are just blatant garbage and have no bearing on your argument.

The actual research behind the findings is great. Clarified a lot of stuff for me. The findings shown above doesn't indicate whether a particular movement is active or passive/motion-dependent. The wrist flexion is considered motion dependent. In other words, the bones involved make that movement, not due to active contraction of the wrist flexors, but due to the other stuff going on.

Oh and interesting that the "Both methods" is making a comeback in Buff's poll. Drink Buff Beer!!

 

[sennoc]

Edit: Forgot to add, if the last statement above is true, pronation then becomes a big contribtor to racquet head speed, albeit indirectly!

Yeah. But it is really important to understand the difference. If you do not understand it, you start to pronate early and your motion is far from being optimal.

Do experiment. Experiment decides

Go on the court, serve a few times using pronation as "a powerful source of energy". Remember, were serves fast, ergonomic?

Then do another set of serves. This time forget everything you've ever heard about pronation. Try to hit the ball holding racquet as a hammer. Try to move racquet's head as a hammer as long as possible and pronate in the very last phase, just before contact, at the last moment. Pronate without huge effort, just rotate your forearm without exertion.

Then think about all those wasted years, come here and I'll give you my account number

 

[moist]

Unless you're a very accomplished server, don't do it. You'll end up squeezing the racquet very tightly to compensate thus putting unnecessary wear on your biceps.

edit: Beaten!

Interesting... I've been rebuilding my serve on the advice of coaches. The main criticism is that I tense up and don't allow myself a full racquet drop. To fix this I've been doing the ultra loose, 2 fingers on the racquet serving drill. The idea being if my grip is loose I need to use the shoulder cartwheel to whip my arm more, and I should be able to feel a full racquet drop better. It's helped a lot, but just like you say my bicep has been hurting. I had attributed it to the high volume of serving practice lately.

 

[BrianGordon]

I was directed to this thread by someone familiar with my work and who seemed to think it was, in small part, relevant in this discussion. Reluctantly due to the tone, I offer input for context, as a researcher, player and coach; and not to spark debate – please take or leave it at its face value.

Because these positions may be deemed “garbage”, I suppose I had better note these statements are based on results published in a peer reviewed scientific journal and/or based on results in a doctoral dissertation (mine) scrutinized ad-nauseum by a committee including two of the top sport biomechanists in the world along with a brutally academic physicist and a fortunately very cool motor control expert – if anyone gives a sh**.

It seems to me good arguments are made by all but that most disagreement relates more to terminology than substance – I could be wrong.

The forearm can be rotated internally (twisted around its longitudinal axis) in primarily two ways when the elbow is nearly straight (like near contact on the serve): (1) by internally rotating (spinning around its longitudinal axis) the upper arm bone (humerus) at the shoulder joint which will rotate (twist) the forearm due to the physical connection between the two at the elbow joint – this is normally referred to as internal rotation of the forearm; (2) by utilizing forearm musculature to cause the radius bone of the forearm to rotate around the ulna (other bone in forearm) independent of the influence of the upper arm – this is true pronation (or supination in the opposite direction).

Wrist joint motion is completely separate from either internal rotation or pronation and includes flexion, extension, radial deviation (towards the thumb side), and ulnar deviation (towards the pinky side). While the joint motions are considered in isolation, some muscles that cross the wrist joint or wrist and elbow joints and can cause both pronation/supination and wrist joint motion to varying degrees – this however is inconsequential to the discussion at hand – so to speak.

With those definitions, I refer interested parties to two threads that may add to, or may complicate this discussion:

On the cause of wrist joint motion and particularly flexion near contact on the “flat” serve (post #22):

http://tt.tennis-warehouse.com/showthread.php?t=256498&page=2

I will add that my current thinking is trending towards the position that desired changes to the relative contribution of wrist flexion to racquet head speed should be done in the context of conscious muscle activation with appropriate physical training and biomechanical manipulation – with subsequent repetition this could result in a shift to a largely sub-cortical (non-conscious) motor “program” – a program that still utilizes muscle constituents to flex the wrist, and a program that is enhanced through further training by development of task specific proprioceptive facilitation (neural enhancement of task specific and associated muscle groups i.e. tricep to wrist flexors).

For those that find the last section to be unintelligible gobble-de-gook I apologize but don’t have time to translate other than – it means that my (and most others) data shows that the late wrist flexion near contact is caused by shortening of muscle/tendon complexes and not motion dependent torques (the empirical part) but that both the conscious and non-conscious advocates may BOTH be correct to a certain extent (the educated guess part) – the degree of the extent is not known at this time.

On the importance of forearm pronation (see definition above) to racquet speed (particularly posts #1 & #8:

http://www.tennisplayer.net/bulletin/showthread.php?t=1520

So... according to my research if by pronation one very loosely means forearm internal rotation due primarily to shoulder internal rotation then it is a huge contributor to racquet speed – if one means true pronation (the forearm RELATIVE to the upper arm), it is a negative (decreases racquet speed) contributor – for high level players on the average - a critical coaching and training distinction in my opinion.

 

[thebuffman]

So... according to my research if by pronation one very loosely means forearm internal rotation due primarily to shoulder internal rotation then it is a huge contributor to racquet speed – if one means true pronation (the forearm RELATIVE to the upper arm), it is a negative (decreases racquet speed) contributor – for high level players on the average.

wow! i am truly blown away. truly. thanks for posting. didn't even know there were different ways to pronate....that you can actually pronate from the shoulder. wow.

 

[bhupaes]

Yeah. But it is really important to understand the difference. If you do not understand it, you start to pronate early and your motion is far from being optimal.

Do experiment. Experiment decides

Go on the court, serve a few times using pronation as "a powerful source of energy". Remember, were serves fast, ergonomic?

Then do another set of serves. This time forget everything you've ever heard about pronation. Try to hit the ball holding racquet as a hammer. Try to move racquet's head as a hammer as long as possible and pronate in the very last phase, just before contact, at the last moment. Pronate without huge effort, just rotate your forearm without exertion.

Then think about all those wasted years, come here and I'll give you my account number

Regardless of my intellectual understanding, I can still thump my serve into the backfence, so I'm sure my physical understanding has been on the right track all along... But I commend you for your insight into the serve mechanics.

So... according to my research if by pronation one very loosely means forearm internal rotation due primarily to shoulder internal rotation then it is a huge contributor to racquet speed – if one means true pronation (the forearm RELATIVE to the upper arm), it is a negative (decreases racquet speed) contributor – for high level players on the average - a critical coaching and training distinction in my opinion.

Thanks for the clarification, Brian. Even my muddled brain can now, if not fully understand, at least appreciate the complexities involved in the serve mechanics!

 

[Bungalo Bill]

Want to poll the general public here on the wrist snap or what we deem "pronation". I have become a huge fan of Pat "The Serve Doctor" Dougherty and his teachings. In his teachings he explains the pronation process to be a natural or autonomic reaction to the elbow abruptly stopping during forward acceleration. I completely subscribe to this doctrine.

I was watching The Tennis Channel the other day and their section on Tips and Drills came on. The instructor expounded on pronation, its importance and the power generated from it. He says that, "increasing your service game is as easy as a snap". In it he is referring to the *snap* of the wrist. He goes on to demonstrate by standing at the service line, holding the serving arm straight up in the air, isolating the wrist in the motion and snapping down on the ball into the adjacent service box. He continued to demonstrate by moving further from the service box hitting serves while maintaining isolation of the wrist (or only using the wrist in the motion...no wind up or arm movement) in the technique and snapping the wrist down on the tossed ball. When he gets the baseline he advocates going ahead and adding a gentle windup to the wrist *snap*.

So I am sitting there pondering these entirely different schools of thought about serve pronation. One methodology advocates not even concentrating on the motion of pronation trusting that pronation will occur as an end result of bringing the flexing body & elbow to an abrupt stop hence whipping the forearm forward and downward toward a point of impact at (not through) the ball. The alternate methodology concentrates primarily on the wrist snap and constructs the service motion around it.

I like Dougherty's method. It is how I serve and it works. I rsrely ever think about the wrist. I simply concentrate on complete relaxation throughout the serve motion. I try to really relax my hititng shoulder and arm.

The serve is mainly motion and you maintaining complete relaxation in your body throughout the motion.

 

[gzhpcu]

Thanks Brian for taking the time to post in this thread. I am always very interested in anything you have to say, as I consider you one of the most knowledgeable in the field of tennis biomechanics.

 

[SystemicAnomaly]

wow! i am truly blown away. truly. thanks for posting. didn't even know there were different ways to pronate....that you can actually pronate from the shoulder. wow.

Well, sort of. Pronation (and supination) are rotations of either the forearm and of the foot, not really used for rotations of the shoulder. Medial (internal) rotation of the shoulder (or upper arm) is a lot like pronation of the forearm. Lateral (external) rotation of the shoulder is akin to supination of the forearm.

Rotation of the hand (and wrist) can be a result of forearm rotation and shoulder rotation. Try the following. Put your elbows at your side bent at 90 degrees and stick your forearms out (forward). You should be able to rotate your hand about 180 degrees by rotating the forearm. Now, extend your arm fully forward (elbows are no longer bent). You should now be able to rotate your hand an additional 90 degrees or more. This additional hand rotation is due to rotations of the shoulder (primarily internal rotation).

Other primary articulations of the shoulders include: flexion, extension, abduction, and adduction. secondary articulations include: circumduction, transverse flexion, transverse extension, transverse abduction, transverse adduction, scapular retraction, scapular protraction, scapular elevation, and scapular depression.

http://www.exrx.net/Articulations/Shoulder.html

http://en.wikipedia.org/wiki/Shoulder#Movements_of_the_shoulder
.

 

[Lsmkenpo]

In my entire tennis career I never consciously thought "I have to snap my wrist" "I have to pronate my forearm" on serve.

Simply relaxing, and using a proper service motion with the racquet coming on edge towards the ball the pronation happens automatically, otherwise you will not make clean contact with the ball. I serve 120 and I never think about snapping my wrist or pronating, all of it came from having a proper motion and staying relaxed.

I see a lot of players with flawed motions forcing the wrist snap or pronation to compensate, often their contact point is the real problem. If there are flaws in your motion fix them before you worry about pronating or snapping your wrist, you may find that it just happens naturally with a relaxed proper service motion and contact point.

 

[charliefedererer]

I was directed to this thread by someone familiar with my work and who seemed to think it was, in small part, relevant in this discussion. Reluctantly due to the tone, I offer input for context, as a researcher, player and coach; and not to spark debate – please take or leave it at its face value.

Because these positions may be deemed “garbage”, I suppose I had better note these statements are based on results published in a peer reviewed scientific journal and/or based on results in a doctoral dissertation (mine) scrutinized ad-nauseum by a committee including two of the top sport biomechanists in the world along with a brutally academic physicist and a fortunately very cool motor control expert – if anyone gives a sh**.

It seems to me good arguments are made by all but that most disagreement relates more to terminology than substance – I could be wrong.

The forearm can be rotated internally (twisted around its longitudinal axis) in primarily two ways when the elbow is nearly straight (like near contact on the serve): (1) by internally rotating (spinning around its longitudinal axis) the upper arm bone (humerus) at the shoulder joint which will rotate (twist) the forearm due to the physical connection between the two at the elbow joint – this is normally referred to as internal rotation of the forearm; (2) by utilizing forearm musculature to cause the radius bone of the forearm to rotate around the ulna (other bone in forearm) independent of the influence of the upper arm – this is true pronation (or supination in the opposite direction).

Wrist joint motion is completely separate from either internal rotation or pronation and includes flexion, extension, radial deviation (towards the thumb side), and ulnar deviation (towards the pinky side). While the joint motions are considered in isolation, some muscles that cross the wrist joint or wrist and elbow joints and can cause both pronation/supination and wrist joint motion to varying degrees – this however is inconsequential to the discussion at hand – so to speak.

With those definitions, I refer interested parties to two threads that may add to, or may complicate this discussion:

On the cause of wrist joint motion and particularly flexion near contact on the “flat” serve (post #22):

http://tt.tennis-warehouse.com/showthread.php?t=256498&page=2

I will add that my current thinking is trending towards the position that desired changes to the relative contribution of wrist flexion to racquet head speed should be done in the context of conscious muscle activation with appropriate physical training and biomechanical manipulation – with subsequent repetition this could result in a shift to a largely sub-cortical (non-conscious) motor “program” – a program that still utilizes muscle constituents to flex the wrist, and a program that is enhanced through further training by development of task specific proprioceptive facilitation (neural enhancement of task specific and associated muscle groups i.e. tricep to wrist flexors).

For those that find the last section to be unintelligible gobble-de-gook I apologize but don’t have time to translate other than – it means that my (and most others) data shows that the late wrist flexion near contact is caused by shortening of muscle/tendon complexes and not motion dependent torques (the empirical part) but that both the conscious and non-conscious advocates may BOTH be correct to a certain extent (the educated guess part) – the degree of the extent is not known at this time.

On the importance of forearm pronation (see definition above) to racquet speed (particularly posts #1 & #8:

http://www.tennisplayer.net/bulletin/showthread.php?t=1520

So... according to my research if by pronation one very loosely means forearm internal rotation due primarily to shoulder internal rotation then it is a huge contributor to racquet speed – if one means true pronation (the forearm RELATIVE to the upper arm), it is a negative (decreases racquet speed) contributor – for high level players on the average - a critical coaching and training distinction in my opinion.

Thanks so much for weighing in.

Tricky actually made your initial point that pronation is largely caused by internal rotation of the upper arm at the shoulder way back in response #56 in this thread, but thanks for putting the exclamation point to it. It is apparent that too many of the posters considered pronation only to be the forearm rotation of the radius about the ulna, and therefore missed the large contribution pronation has on the serve speed.

 

[charliefedererer]

Wrong. Sampras begins the act of "pronation" on the very first photo in the sequence you provided. He is finally in a "prone" position at impact (113 mph) second photo. Therefore, by "pronating" he has gone from 50 to 113 mph racquet head speed. In the 3rd, 4th, 5th, and 6th photos, he is passed a "prone" position, and the ball has already been struck, so anything he does at this point is insignificant to ball speed and or energy.

In the following video, Roddick begins to pronate at the 4 second mark. He is in the "prone" position and has fully pronated by the time he makes impact with the ball (9 seconds).

In the sceond sequence, he is in a prone position at the 16 second mark. Therefore, has already "pronated", which results with all that energy being delivered to the ball.

In the third sequence, he begins the act of pronation around the 41 second mark.

http://www.youtube.com/watch?v=SZbxKuLEP_o

Thanks for pointing out how early the pronation process begins. In fact I am sure you would agree that it starts out even earlier than the first photo that sennoc posted, as Sampras supinated his foream at the lowest point in his racquet drop, so that pronation actually starts as soon as he begins to swing his racquet upward.

But thanks to all the contributors on this thread. The discussion is one of the most enjoyable I have seen on TT. The dialogue points out far more than a simple explanation of pronation ever could have.

 

[sennoc]

Thanks for pointing out how early the pronation process begins. In fact I am sure you would agree that it starts out even earlier than the first photo that sennoc posted, as Sampras supinated his foream at the lowest point in his racquet drop, so that pronation actually starts as soon as he begins to swing his racquet upward.

Pronation, as an action of muscles, is totally not important as long as it does not have any impact on the racquet's head. So, if you do not look biomechanically but physicially (as do I) you see that there is no pronation at all on the first frame of "my" sequence of images of Sampras' serve.

I'm also quite sure that Sampras starts pronation of his forearm as late as possible.

 

[pvaudio]

We're still debating this? THe motion of how to serve properly using prnation as applied to tennis needs to be taught. Done deal. Once taught, it becomes autonomic. Done.

The biomechanical arguments are ridiculous because all it is is people using semantics so that they have their own way. Does literally pronating the wrist cause an increase in racquet head speed? No. Does the entire motion which INCLUDES pronation and is thus called such when referring to tennis cause an increase in racquet head speed? Yes. Done.

 

[tricky]

After meditating over this issue (i.e. reading in the bathroom), I think Brian Gordon is right about wrist flexion being active.

For wrist flexion to be active consciously, all it needs is for hand (i.e. palm muscles right under the fingers) to stretch during the backswing. Now, if you hold the handle like a hammer (a la Pat), this will likely happen.

 

[Bungalo Bill]

We're still debating this? THe motion of how to serve properly using prnation as applied to tennis needs to be taught. Done deal. Once taught, it becomes autonomic. Done.

The biomechanical arguments are ridiculous because all it is is people using semantics so that they have their own way. Does literally pronating the wrist cause an increase in racquet head speed? No. Does the entire motion which INCLUDES pronation and is thus called such when referring to tennis cause an increase in racquet head speed? Yes. Done.

I agree. Done.

I dont even teach pronation. That is something I setup the arm to do without the student even knowing it. I do not want the student to focus on one part of the body. I want them to get the motion down. Done.

Pronation happens indirectly just by teaching someone to serve the ball.

Done.