# The Tennis Serve - What's True?

#### optic yellow

##### Legend
If the use of terms winds up with ambiguity, then - for technical discussions of pitching or serving - changes are due.
Agreed. Muddled technical terms are one of the biggest impediments to learning.

The baseball pitch gets hand speed from IRS when the elbow is bent. ISR with the bent elbow is obvious and can not be confused with pronation. That probably accounts for why baseball pitching could not hide and muddle ISR. ?

But late in the pitch approaching release, when the elbow is near straight, then it is difficult to distinguish ISR from Pronation.

Yes this is how the kinetic chain releases. First ISR turns the whole upper extremity, then extending the elbow casts the upper half of the upper extremity out, then pronation turns the tip of the upper extremity beyond that. It is the combination of all these forces (plus ones more proximal) working correctly on top of each other that achieves optimum power output.

The serve can develop racket head speed with a near straight elbow because of the racket. The elbow is straightening when IRS starts, see high speed videos for timing and variety relative to ISR

The racquet is just an extension of the hand so whatever applies to accelerating the hand applies to accelerating the head of the racquet.

#### Chas Tennis

##### G.O.A.T.
Agreed. Muddled technical terms are one of the biggest impediments to learning.

Yes this is how the kinetic chain releases. First ISR turns the whole upper extremity, then extending the elbow casts the upper half of the upper extremity out, then pronation turns the tip of the upper extremity beyond that. It is the combination of all these forces (plus ones more proximal) working correctly on top of each other that achieves optimum power output.

The racquet is just an extension of the hand so whatever applies to accelerating the hand applies to accelerating the head of the racquet.

I divide the serve ISR into simple and complicated. For high speed videos, I can estimate some simple things. For IRS, the rotation axis of ISR is simple and very important for racket head speed. It's through the upper arm bone, humerus. Also, the angle between the forearm and racket shaft determine the radius out from the IRS rotation axis when the elbow angle is near straight.

The thumbnail frame (shown) of this video shows the simple view of how ISR develops its contribution to racket head speed with a near straight elbow. The radius out is the distance between the IRS rotation axis (orange arrow) and the impact spot on the racket face.
To single frame on Youtube, stop video and use the period & comma keys.

When the elbow has a considerable bend, things are too complicated for high speed video in 2 dimensions and the racket head faces a direction that depends on both the instanteous elbow angle and the instanteous angle of ISR.

The baseball pitch is simple when the elbow angle largely determines the radius out from the ISR axis. It gets very complicated when the elbow is near straight and the hand somehow determines the radius out - too complicated. I don't understand the radius out when the elbow is near straight or how much pronation & ISR vs time are occurring for the pitch.

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#### a12345

##### Professional
Pronation is more to do with the direction of the serve.

Heres a video of Mouratoglou teaching Rune, whos currently ranked 28 in the world, how to pronate in order to serve out wide right from the left side of the court.

So you might get videos of pronation and no pronation depending on the type of serve being hit and on which side of the court the serve is on.

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#### TennisCJC

##### Legend
Pronation is more to do with the direction of the serve.

Heres a video of Mouratoglou teaching Rune, whos currently ranked 28 in the world, how to pronate in order to serve out wide right from the left side of the court.

So you might get videos of pronation and no pronation depending on the type of serve being hit and on which side of the court the serve is on.

I think Patrick M is incorrect. Both the slice serve to the right side of the box and the flat serve to the left side of the box have pronation or ISR (to me they are the same thing). For a slice serve, the pronation occurs later during and after contact which allows the racket head to attack the ball on edge and to move on a more R to L swing path. For a flat serve, the pronation occurs earlier to open the strings up to the ball before contact and there is less R to L angle in the swing path. I believe all serves have pronation/ISR including slice, flat, kick and top/slice when a good grip and technique is used.

As far as using the term pronation or ISR, I think there is merit in understanding that the shoulder joint is driving the pronation of the forearm. But, traditionally, the term pronation has been used for decades in tennis. I can not pronate my forearm without ISR movement at the shoulder joint personally and think most people are the same. Pronation and ISR go together in my view but understanding it as a shoulder movement instead of an isolated forearm movement may be helpful to some as a teaching aid.

#### Chas Tennis

##### G.O.A.T.
Pronation is more to do with the direction of the serve.

Heres a video of Mouratoglou teaching Rune, whos currently ranked 28 in the world, how to pronate in order to serve out wide right from the left side of the court.

So you might get videos of pronation and no pronation depending on the type of serve being hit and on which side of the court the serve is on.
Bruce Elliott said, about 20 years ago, that pronation may be adjusted to control the side-to-side orientation of the racket face. In the meantime, the racket face is accelerated to high speed largely using ISR and some other joint motions.

Suppose that ISR muscles accelerated the racket head to high speed and - before impact - the ISR muscles ceased providing any more forces. Is it true that the 100 MPH racket head and rotating straight arm might continue on at high speed - from inertia according to Newton's law - and that inertia might cause forearm pronation to appear? Of course it can, because inertia is true as described by Newton in the 1600s...... But if in 2022, we can only use a few words to describe tennis strokes, instead of high speed videos, a little complexity will throw us for a loop. Pronation-ISR-Pronation-ISR-.............ISR-pronation....

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#### a12345

##### Professional
I dont think pronation adds anything much to the power because when you think about it pronation essentially moves independently of all the other muscles and body movements before it.

If I pronate from a standing position, and then I pronate after going through the full serve motion, i think the speed of the pronation will be roughly the same in both scenarios because the maximum speed you can turn your wrist is not really related to the other muscle movements.

If I lie down on my back and pronate I can probably pronate at the same speed as the other 2 scenarios. So the power in the serve must come from elsewhere.

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#### JohnYandell

##### Hall of Fame
There is no pronation on the serve. The ignorance on that point is probably immortal.

#### ballmachineguy

##### Hall of Fame
I wonder if people that don’t understand the chemical formulas involved in combustion reactions enjoy driving less.

#### Chas Tennis

##### G.O.A.T.
I hope that this 2008 video will soon be replaced with another that accurately describes pronation and internal shoulder rotation during the tennis serve.

#### optic yellow

##### Legend
I hope that this 2008 video will soon be replaced with another that accurately describes pronation and internal shoulder rotation during the tennis serve.
I've always wondered, is this the same FuzzyYellowBalls that posts here?

#### zill

##### Legend
I hope that this 2008 video will soon be replaced with another that accurately describes pronation and internal shoulder rotation during the tennis serve.

Nothing wrong with the contents here. It emphasis pronation. ISR exists but he didn't talk about it in this vid.

#### Chas Tennis

##### G.O.A.T.
Nothing wrong with the contents here. It emphasis pronation. ISR exists but he didn't talk about it in this vid.

Do you think that the average reader
1) would understand that ISR supplies most of the racket head speed for the serve?
OR
2) would not have a thought of ISR?

"Nothing wrong with the contents here."
Also, there are other things wrong with the content.

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#### zill

##### Legend
"Nothing wrong with the contents here."
Also, there are other things wrong with the content.

Like what else would you say is wrong here?

#### optic yellow

##### Legend
Nothing wrong with the contents here. It emphasis pronation. ISR exists but he didn't talk about it in this vid.
His point is that you want to emphasize ISR because ISR is the single most important source of racquet head acceleration in a serve.

#### nyta2

##### Hall of Fame
I hope that this 2008 video will soon be replaced with another that accurately describes pronation and internal shoulder rotation during the tennis serve.
when is your video coming out?

#### FiddlerDog

##### Hall of Fame
I've always wondered, is this the same FuzzyYellowBalls that posts here?

No, this was the guy

#### optic yellow

##### Legend
No, this was the guy
ty

#### socallefty

##### G.O.A.T.
What words do active coaches teaching students every day use to get a student to swing properly and get maximum power on the serve? No coach typically uses terms like EST, ISR etc. as far as I know in real life as those are not commonly understood terms unless you are teaching medical students. Even though ESR and ISR are accurate descriptions of the actual shoulder rotation used in a high speed serve, what terms or words did coaches use to teach the student who has a high caliber serve?

How do you talk to a student to get them to swing the correct way to generate maximum pace without giving them an anatomy lesson about shoulder rotation? And do you teach them different arm motions if they want to serve a flat serve wide or DTM like Patrick Mouratoglou does in the video above where he is coaching Holger Rune?

#### JohnYandell

##### Hall of Fame
You just show them the correct physical positions. Have them model them and create internal mental images. Video them and work to get approximations. You are right they don't need the biomechanical terminology.

#### Chas Tennis

##### G.O.A.T.
What words do active coaches teaching students every day use to get a student to swing properly and get maximum power on the serve? No coach typically uses terms like EST, ISR etc. as far as I know in real life as those are not commonly understood terms unless you are teaching medical students. Even though ESR and ISR are accurate descriptions of the actual shoulder rotation used in a high speed serve, what terms or words did coaches use to teach the student who has a high caliber serve?

How do you talk to a student to get them to swing the correct way to generate maximum pace without giving them an anatomy lesson about shoulder rotation? And do you teach them different arm motions if they want to serve a flat serve wide or DTM like Patrick Mouratoglou does in the video above where he is coaching Holger Rune?

I like this discussion. Bruce Elliott has been teaching coaches for many years.

#### Digital Atheist

##### Hall of Fame
How do you talk to a student to get them to swing the correct way to generate maximum pace without giving them an anatomy lesson about shoulder rotation? And do you teach them different arm motions if they want to serve a flat serve wide or DTM like Patrick Mouratoglou does in the video above where he is coaching Holger Rune?
The shoulder rotation thing is interesting. Having recently posted in the Video Serve Analysis thread, where there was a conversation about shoulder rotation (vertical versus horizontal axis) along with body rotation - specifically over rotation - this is something I'm trying to understand more. Imo it is obviously quite a common problem among amateurs, and something I can actually feel myself doing from time to time. I've been working on not tossing into the court as much since that is a definite trigger for me; other than trying to stay a little more sideways early in the racquet drop stage, I haven't focused on anything else. That's because, once we've seen a live demonstration of what we want to achieve, I firmly believe we have to find ways of tricking the body with cues or thoughts that the brain already understands, and so they can't be bio-mechanical in nature.

I posted images of Serena Williams in another thread about camera angles and judging low elbows at trophy (added again down below).Then seeing another image of her posted by @ballmachineguy, I went out yesterday and hit a few from a similar angle (not quite exact, but very close).

Full size image can be downloaded here. [You will have to zoom if continuing to view inside the browser for better clarity]

@Curious, does that not look like shoulder over shoulder to you?

I think frame 2 is called maximum ESR and frames 4 through 7 are ISR (although I always thought it was a combination of pronation and ISR, and that's why Chas looked for shadows on the elbow and upper arm, which obviously aren't present here). I shouldn't have worn the hoody, but it was windy and cold.

Roddick for comparison versus frames 5 and 6 (frame 6 is just past contact for me but the video was 60fps and is the closest match)

Serena versus frame 2:

As a reminder of what camera angles can do, Serena's elbow (which isn't low).

I used to be worried about that, but I now think I'm well within the 20° range of acceptability that Brian Gordon prescribes (rear views of my serve from other videos are contributing factors to that belief).

Edit: Now I'm more concerned about that disgusting thing I'm doing with my little finger, and wonder how I can change that to the middle digit! Seriously though, what's up with that???

Do you think that the average reader
1) would understand that ISR supplies most of the racket head speed for the serve?
OR
2) would not have a thought of ISR?
No to both. But they don't need to do they? Coaches and bio-mechanical scientists can study that stuff using high speed video and find out precisely what is going on. Then they can find ways to help make those things happen in a live environment by attempting to identify drills that work over time (initially there will be trial and error). Which is what I believe Brian Gordon does, as you state above.

There is no pronation on the serve. The ignorance on that point is probably immortal.
Interesting point, and I've never heard you state it that directly before (not saying you haven't, just that I haven't seen it)! Based on your Karlovic statement above, does that mean in my montage I am using ISR to reach frame 7?

Final question for the gurus - do I still need to worry about over rotation, and if so, any advice on drills to help?

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#### Curious

##### G.O.A.T.
@Curious, does that not look like shoulder over shoulder to you?
100%.
Looking great.

#### Curious

##### G.O.A.T.
There is no pronation on the serve. The ignorance on that point is probably immortal.
I’m assuming you’re serious.
There’s no way you can hit a continental grip serve without pronation. ISR wouldn’t be enough to get the string bed square to the ball. With a semi western fh grip though you don’t need pronation.

#### optic yellow

##### Legend
Pronation is more about controlling racquet face and ISR is more about providing the motive force as I understand it.

#### Digital Atheist

##### Hall of Fame
I like this discussion. Bruce Elliott has been teaching coaches for many years.
I've downloaded and watched the serve section of that video quite a few times. Very good stuff. Interesting comments about the back hip @11:10.

#### Digital Atheist

##### Hall of Fame
I’m assuming you’re serious.
There’s no way you can hit a continental grip serve without pronation. ISR wouldn’t be enough to get the string bed square to the ball. With a semi western fh grip though you don’t need pronation.
I read somewhere on here that these numbers may not be completely accurate based on new research, since they are a little old. However:

The articles are:
1. Contributions of Upper Limb Segment Rotations During the Power Serve in Tennis, by Bruce C. Elliott, Robert N. Marshall, and Guillermo J. Noffal. Published in the Journal of Applied Biomechanics, 1995.
2. Long Axis Rotation: The missing link in proximal to distal segmental sequencing, by Marshall & Elliott. Published in The Journal of Sports Science, 2000.

So no wonder it is hard to determine what's true!

#### Curious

##### G.O.A.T.
I read somewhere on here that these numbers may not be completely accurate based on new research, since they are a little old. However:

The articles are:
1. Contributions of Upper Limb Segment Rotations During the Power Serve in Tennis, by Bruce C. Elliott, Robert N. Marshall, and Guillermo J. Noffal. Published in the Journal of Applied Biomechanics, 1995.
2. Long Axis Rotation: The missing link in proximal to distal segmental sequencing, by Marshall & Elliott. Published in The Journal of Sports Science, 2000.

So no wonder it is hard to determine what's true!
Pronation contributes 5% but hand flexion 30%??

#### AnyPUG

##### Hall of Fame
I’m assuming you’re serious.
There’s no way you can hit a continental grip serve without pronation. ISR wouldn’t be enough to get the string bed square to the ball. With a semi western fh grip though you don’t need pronation.

If ISR is correctly employed, pronation is absent or extremely insignificant. Accidental or intentional pronation will produce low quality serve.
Think about it, why would you need pronation when have ISR? It's like, if you are flying, what will you do with your bicycle? Of course, you can carry it as a check-in luggage (but as carry-on item will be extremely inconvenient - just like pronation with ISR).

#### user92626

##### G.O.A.T.
If ISR is correctly employed, pronation is absent or extremely insignificant. Accidental or intentional pronation will produce low quality serve.
Think about it, why would you need pronation when have ISR? It's like, if you are flying, what will you do with your bicycle? Of course, you can carry it as a check-in luggage (but as carry-on item will be extremely inconvenient - just like pronation with ISR).
Copy us a youtube clip showing what you're talking about. Correct ISR and no pronation. Youtube should have thousands of clips of pros for you to choose from. Pros should be a good example, right?

#### AnyPUG

##### Hall of Fame
Copy us a youtube clip showing what you're talking about. Correct ISR and no pronation. Youtube should have thousands of clips of pros for you to choose from. Pros should be a good example, right?

Nick knows what he is talking about and he says pronation will ruin your serve if you try -

#### user92626

##### G.O.A.T.
Nick knows what he is talking about and he says pronation will ruin your serve if you try -

Cool. Let my try and change my serve once again

The @Curious disease is strong with me!

#### Chas Tennis

##### G.O.A.T.
The shoulder rotation thing is interesting. Having recently posted in the Video Serve Analysis thread, where there was a conversation about shoulder rotation (vertical versus horizontal axis) along with body rotation - specifically over rotation - this is something I'm trying to understand more. Imo it is obviously quite a common problem among amateurs, and something I can actually feel myself doing from time to time. I've been working on not tossing into the court as much since that is a definite trigger for me; other than trying to stay a little more sideways early in the racquet drop stage, I haven't focused on anything else. That's because, once we've seen a live demonstration of what we want to achieve, I firmly believe we have to find ways of tricking the body with cues or thoughts that the brain already understands, and so they can't be bio-mechanical in nature.

I posted images of Serena Williams in another thread about camera angles and judging low elbows at trophy (added again down below).Then seeing another image of her posted by @ballmachineguy, I went out yesterday and hit a few from a similar angle (not quite exact, but very close).

@Curious, does that not look like shoulder over shoulder to you?

I think frame 2 is called maximum ESR and frames 4 through 7 are ISR (although I always thought it was a combination of pronation and ISR, and that's why Chas looked for shadows on the elbow and upper arm, which obviously aren't present here). I shouldn't have worn the hoody, but it was windy and cold.

Roddick for comparison versus frames 5 and 6 (frame 6 is just past contact for me but the video was 60fps and is the closest match)

Serena versus frame 2:

As a reminder of what camera angles can do, Serena's elbow (which isn't low).

I used to be worried about that, but I now think I'm well within the 20° range of acceptability that Brian Gordon prescribes (rear views of my serve from other videos are contributing factors to that belief).

No to both. But they don't need to do they? Coaches and bio-mechanical scientists can study that stuff using high speed video and find out precisely what is going on. Then they can find ways to help make those things happen in a live environment by attempting to identify drills that work over time (initially there will be trial and error). Which is what I believe Brian Gordon does, as you state above.

Interesting point, and I've never heard you state it that directly before (not saying you haven't, just that I haven't seen it)! Based on your Karlovic statement above, does that mean in my montage I am using ISR to reach frame 7?

Final question for the gurus - do I still need to worry about over rotation, and if so, any advice on drills to help?
Around 1952, Harold Edgerton, a leading researcher in high speed imaging including stroboscopic photography, photographed Gussie Moran's serve using stroboscopic techniques with light flashes of microseconds duration that are repeated.
http://edgerton-digital-collections.org/?s=hee-nc-49001#hee-nc-49001

See numbers on the picture.
#1 Her foot stays on the ground. Prior to 1962 the rules of tennis required that one foot remain on the ground. All serving techniques prior to that time required that one foot remain on the ground. The leg thrust/jump used in the current tennis serve is now much greater and that affects comparisons to serves before the rule change.

#2 The racket is oriented 'edge on' to the ball, a checkpoint for a high level serving technique. An estimated, 50% of active tennis players do not have their rackets oriented edge on and therefore have a lower performance serving technique. Most don't know.

#3 The racket head has rotated both forward and into the page between #2 and #3. The apparent length of the racket has shortened between #2 and #3 because the racket is viewed at an angle in #3. Place a paper on the screen to measure the apparent racket length difference. Between #2 and #3 the arm and racket are accelerated to high rotation rates into the page by the joint motion of internal shoulder rotation (ISR). There is some evidence that ISR stops accelerating before impact. ? At impact one estimate is that 40% of racket head speed is caused by ISR and 60% is caused by the other swinging motions. The significant part played by ISR was not understood for the tennis serve until about 1995, when researchers B. Elliott, R. Marshall and G. Noffal began publishing research results. In the 1970s, I had carefully studied similar strobe photos in Vic Braden's Tennis for the Future, but I had somehow missed noticing the important racket edge orientations produced by internal shoulder rotation. Upper arm rotation at the shoulder (ISR) never crossed my mind until 2011. Most tennis players don't understand what is shown in the strobe picture.

#4 Peak of the toss.

#5 Ball location at impact.

#6 Racket position after impact.The high speed arm rotation and racket head continue forward after impact probably from momentum with little ISR muscle forces.

#7 Ball trajectory with a downward projection angle as for nearly all serves including kick serves.

#8 Compare the hand and racket face orientations in #2 and #8. The thumb is up in both #2 and #8. There has been about 180° of rotation. That 180° rotation probably came from both ISR and pronation.

Leading up to impact, muscle forces cause ISR to accelerate the arm and racket very rapidly. But ISR continues into the follow through at high speed after the muscle forces have stopped.

You can see similar numbered serve positions in pictures and videos of current serves, except now both feet will be in the air.

"2" The racket is about 'edge on' to the ball - a checkpoint that indicates that this might be a high level serve - and the elbow has just become near straight. The elbow is straight.

"3" The racket is swinging plus ISR is occurring. Usually from this side view, the length of the racket will appear shorter because the racket it tilted away from the camera's line of view. The elbow is straight.

"4" Shows part of the toss trajectory.

"5" Shows the location of impact. For slice & flat serves, from the side camera view only, the racket shaft usually appears straight up at around impact (give or take a very few degrees.)

"6" Is after impact.

The quality of a high level serve will depend on the technique of the ISR sub-motion shown between 2 and 5, but IRS depends on the earlier motions that pre-stretch ISR muscles before 2, the start of ISR.

This region lies between frame 5 & 6 of the sequence below. IRS - start to impact - lasts only about 20-30 milliseconds. Sequences are very useful because it is difficult to remember what occurs before or after the frame that we are viewing.

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#### Digital Atheist

##### Hall of Fame
Pronation contributes 5% but hand flexion 30%??
Yes, that's always weirded me out a little too. @optic yellow pointed out why pronation isn't a speed contributor - it is purely for aligment while ISR is the power source. But then I don't even fully understand some of those headings! This might actually be the part that has changed over the years?

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#### Chas Tennis

##### G.O.A.T.
Yes, that's always weirded me out a little too. But then I don't even fully understand some of those headings! This might actually be the part that has changed over the years?
When considering 'contributions' an undefined word in most usage, keep joint motions and muscular forces separated in your thoughts.

For example, ISR for the serve may start with strong muscular forces and cause the upper arm to rotate with much acceleration. But then those IRS forces may decrease and stop before impact. What if those muscular forces cease entirely before impact? ISR continues on by inertia with no muscular forces. It slows and when it slows maybe the lower arm with racket with its inertia cause them to move ahead - that would be a small amount of real pronation. Or maybe the IRS is timed a little differently by each ATP server. Here's where an overhead camera view could show some interesting angles.

Maybe the problem with 3D motion capture system measurements has been solved? Joint motions involve the joints and bones. But 3D motion capture systems attach reflective balls to the skin and that may flop around for rotations like ISR. ??

#### Curious

##### G.O.A.T.
If ISR is correctly employed, pronation is absent or extremely insignificant. Accidental or intentional pronation will produce low quality serve.
Think about it, why would you need pronation when have ISR? It's like, if you are flying, what will you do with your bicycle? Of course, you can carry it as a check-in luggage (but as carry-on item will be extremely inconvenient - just like pronation with ISR).
What J.Yandell said is ‘there’s no pronation on the serve “.
Maybe I took it too literally and he meant it’s negligible compared to ISR. Anyway there’s pronation of course and i would have guessed its contribution to the serve would be much higher than the 5% given in the article. Pronation is the last element of the kinetic chain or the whip and from a standstill it may not be that powerful but when added to an already speeding racket it can add quite a bit of extra pace in my opinion.

#### Digital Atheist

##### Hall of Fame
This region lies between frame 5 & 6 of the sequence below. IRS - start to impact - lasts only about 20-30 milliseconds. Sequences are very useful because it is difficult to remember what occurs before or after the frame that we are viewing.
OK, that makes sense. Yes, I now know you like sequenced montages and they do seem useful. So here are all those frames, with the last one being just after contact (again, only 60fps and this is a reasonably fast part of the motion but very little blur).

I didn't include every frame initially because I was trying to include common checkpoints. So here is the continuation from that point until landing.

I tried experimenting with the high elbow finish (ala Sampras) but that doesn't work for me.

One other thing I've noticed from serve videos posted on here is that, along with incorrect use of the body, many players end up trying to use their legs (because they know the legs are a power source) but are actually falling slightly going into contact so the timing is off. I agree with this completely:

And this:

The throw demo @ 2:15 is an example of why I also disagree with the argument "the serve is not a throwing motion" with respect to the usefulness of throwing drills. Even though I accept a serve is not exactly the same as a throw, some of the mechanics can definitely be developed and enhanced using a throw like that. I have no science to back this opinion up - it is purely anecdotal from my pov, but also from others who have experienced the same thing.

Imo that really is detrimental to learning how to develop correct upper body mechanics (a proper arm swing), and I think it's why Brian Gordon likes the term "probation", which is his version of the half serve advocated by Salzenstein and some others. Possibly also one reason why half serve drills are recommended on here all the time - such an under utilised drill imo.

Rick Macci is a great coach and advocates for an actual jump. I've never seen anyone say "jump" like that before. Scary!

There are several videos out there like that one.

With respect to what is true, here's my next question. Does landing further inside the court necessarily result in better weight transfer and a better serve? The answer based on my own personal experience is no. In fact that is one of my problems - chasing the toss and trying to land well inside the court actually diminishes my power.

That last serve which is - according to them - better, has a landing position not nearly as far into the court (better back leg loading and not leaning in before going at the ball). He has also gone from an "on-edge" style drop (like Serena) to something far more open (quite close to Sampras actually). I hope that didn't hurt too much to read @Curious!

#### Curious

##### G.O.A.T.
I tried experimenting with the high elbow finish (ala Sampras) but that doesn't work for me.
One of those weird things that I obsess about. I don’t like that straight arm finish like yours, mine and Federer’s. I feel there’s a problem with that! Sampras and Djokovic way with elbow bent and pointing up seems more correct.

#### Digital Atheist

##### Hall of Fame
One of those weird things that I obsess about. I don’t like that straight arm finish like yours, mine and Federer’s. I feel there’s a problem with that! Sampras and Djokovic way with elbow bent and pointing up seems more correct.

Do you know how many ATP and WTA servers with absolute bombs you are going to have to break that news to? That evidence alone should tell you it isn't wrong or problematic. You consider yourself an evidence based thinker as I recall, so how do you explain all those pros with the exact same problem? Serena is probably feeling good about her retirement after hearing this revelation!

If I didn't know better I'd say you were trolling, but I know you're not. I consider you to be stubborn, but certainly in no way stupid, and Imo the problem is you're allowing your feelings to dictate (or in this case mislead) focus. So instead of working on things that actually matter, you've become obsessed with certain aspects of the serve (and other strokes it seems) that are personal preference and stylistic. Those are not to be confused with fundamentals - the things common to all good serves. If on the other hand you could just admit you don't like how the straight arm follow-through looks and stopped short of labelling it a problem, then I could accept that position, even though it won't improve your serve.

Ponder on this question for a moment; how long did it take you to come around on the open racquet drop? If you still held the belief that the open drop is a serious flaw, then that puts Mr Federer in a right pickle. Now he has two major serve issues, and he's only one of the best servers of all time. Go figure. Probably lucky he is also in retirement so he can go cry over a beer with maybe the best female server ever!

<still_shook>

#### Curious

##### G.O.A.T.

Do you know how many ATP and WTA servers with absolute bombs you are going to have to break that news to? That evidence alone should tell you it isn't wrong or problematic. You consider yourself an evidence based thinker as I recall, so how do you explain all those pros with the exact same problem? Serena is probably feeling good about her retirement after hearing this revelation!

If I didn't know better I'd say you were trolling, but I know you're not. I consider you to be stubborn, but certainly in no way stupid, and Imo the problem is you're allowing your feelings to dictate (or in this case mislead) focus. So instead of working on things that actually matter, you've become obsessed with certain aspects of the serve (and other strokes it seems) that are personal preference and stylistic. Those are not to be confused with fundamentals - the things common to all good serves. If on the other hand you could just admit you don't like how the straight arm follow-through looks and stopped short of labelling it a problem, then I could accept that position, even though it won't improve your serve.

Ponder on this question for a moment; how long did it take you to come around on the open racquet drop? If you still held the belief that the open drop is a serious flaw, then that puts Mr Federer in a right pickle. Now he has two major serve issues, and he's only one of the best servers of all time. Go figure. Probably lucky he is also in retirement so he can go cry over a beer with maybe the best female server ever!

<still_shook>
I agree but still feel there’s something wrong both with open drop and straight arm finish. It’s just a feeling but I can’t pretend it’s not there.

#### Chas Tennis

##### G.O.A.T.
OK, that makes sense. Yes, I now know you like sequenced montages and they do seem useful. So here are all those frames, with the last one being just after contact (again, only 60fps and this is a reasonably fast part of the motion but very little blur).

I didn't include every frame initially because I was trying to include common checkpoints. So here is the continuation from that point until landing.

I tried experimenting with the high elbow finish (ala Sampras) but that doesn't work for me.

One other thing I've noticed from serve videos posted on here is that, along with incorrect use of the body, many players end up trying to use their legs (because they know the legs are a power source) but are actually falling slightly going into contact so the timing is off. I agree with this completely:

And this:

The throw demo @ 2:15 is an example of why I also disagree with the argument "the serve is not a throwing motion" with respect to the usefulness of throwing drills. Even though I accept a serve is not exactly the same as a throw, some of the mechanics can definitely be developed and enhanced using a throw like that. I have no science to back this opinion up - it is purely anecdotal from my pov, but also from others who have experienced the same thing.

Imo that really is detrimental to learning how to develop correct upper body mechanics (a proper arm swing), and I think it's why Brian Gordon likes the term "probation", which is his version of the half serve advocated by Salzenstein and some others. Possibly also one reason why half serve drills are recommended on here all the time - such an under utilised drill imo.

Rick Macci is a great coach and advocates for an actual jump. I've never seen anyone say "jump" like that before. Scary!

There are several videos out there like that one.

With respect to what is true, here's my next question. Does landing further inside the court necessarily result in better weight transfer and a better serve? The answer based on my own personal experience is no. In fact that is one of my problems - chasing the toss and trying to land well inside the court actually diminishes my power.

That last serve which is - according to them - better, has a landing position not nearly as far into the court (better back leg loading and not leaning in before going at the ball). He has also gone from an "on-edge" style drop (like Serena) to something far more open (quite close to Sampras actually). I hope that didn't hurt too much to read @Curious!

I take your 5 frame sequence and expand the last frames to fill my phone screen. Then I take a piece of paper or index card and make marks to measure the length of your racket in frames 3, 4 and 5.. I get your racket length in frame 4 to be the longest. That is the opposite of what I would expect and what I pointed out in the strobe picture of Gussie Moran. Why is that? I would say that it could be that you have not done enough ISR from frame 3 to 4. Did the racket turn back away from the camera and up? Compare racket length in your picture to the racket length marked "3" in the strobe picture. This racket length was missed for the decades before 1995 research confirmed ISR. I use it to see if ISR might be occurring. To understand what I'm saying readers must look at the racket lengths.

If you video the elbow close up, the shadows at the elbow can indicate ISR directly. To do that the image has to be close up of the elbow, fast shutter for small motion blur and favorable lighting for shadows, direct sunlight at a good time of day. Then what's true can just be seen.

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#### ballmachineguy

##### Hall of Fame
I tried experimenting with the high elbow finish (ala Sampras) but that doesn't work for me.

One other thing I've noticed from serve videos posted on here is that, along with incorrect use of the body, many players end up trying to use their legs (because they know the legs are a power source) but are actually falling slightly going into contact so the timing is off. I agree with this completely:

Rick Macci is a great coach and advocates for an actual jump. I've never seen anyone say "jump" like that before. Scary!

There are several videos out there like that one.
The legs aren’t a big power source for the serve. They create the potential for power by maximizing ESR. Greater ESR provides the possibility of greater ISR. When you jump, the fastest part of the jump is when you leave the ground. It is slower but gaining speed before that point and gravity starts slowing it after that point. Your racquet is forced to its lowest point (ESR) while the jump is at its fastest point. That is why you are trying to get the racquet at max drop when leaving the ground. The racquet achieves its greatest speed from bouncing out of max ESR into ISR.

IMO, you don’t DO a high elbow finish, it does you, kind of. The more you think of diving with power (force) from edge-to-edge through contact, the more likely you will have a straight arm. The more you snap, as quickly as possible from edge-to-edge through contact, the more you will get that elbow bend that looks like a high elbow finish

#### Digital Atheist

##### Hall of Fame
I take your 5 frame sequence and expand the last frames to fill my phone screen. Then I take a piece of paper or index card and make marks to measure the length of your racket in frames 3, 4 and 5.. I get your racket length in frame 4 to be the longest. That is the opposite of what I would expect and what I pointed out in the strobe picture of Gussie Moran. Why is that? I would say that it could be that you have not done enough ISR from frame 3 to 4. Did the racket turn back away from the camera and up? Compare racket length in your picture to the racket length marked "3" in the strobe picture. This racket length was missed for the decades before 1995 research confirmed ISR. I use it to see if ISR might be occurring. To understand what I'm saying readers must look at the racket lengths.
I understand what you are saying, and thanks for that explanation. Quite an interesting approach but I can see how it works. You are probably correct in your reasoning as to why, which isn't really that surprising!

Edit: I took a look at Serena using some decent footage from Essential Tennis (opposite side, but that shouldn't matter if the racquet still has the internal angle shortening the viewing perspective), and on most of those serves, using your index card approach (cool idea) there is negligible difference between the big L and a comparable frame from those above. It is hard to tell of course, but I rotated the exact same red line (hard to see sorry, but you get the picture).

Source:

Not match play, but she isn't just dinking those in, and I went for one where she followed way through on the opposite side of her body so there was a fair amount of effort.

So one other possibility is that between frames 3 and 4 there is more of an angle, and a slightly shorter racquet will appear somewhere in there. Whereas frame 4 is when I actually start to square up more (sooner than your lightbulb images). Most pro serves probably still have that slight angle even later in the motion, which also enables better use of ISR to generate more power. Having said that, Serena is almost exactly at my position and her racquet lengths are identical, so I don't know.

I really like the elbow shadow idea and will give that a whirl.

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#### optic yellow

##### Legend
Pronation contributes 5% but hand flexion 30%??
Forearm pronation is two muscles with poor leverage throughout the range of motion whereas wrist flexion is several muscles with strong leverage.

#### Digital Atheist

##### Hall of Fame
The legs aren’t a big power source for the serve. They create the potential for power by maximizing ESR. Greater ESR provides the possibility of greater ISR. When you jump, the fastest part of the jump is when you leave the ground. It is slower but gaining speed before that point and gravity starts slowing it after that point. Your racquet is forced to its lowest point (ESR) while the jump is at its fastest point. That is why you are trying to get the racquet at max drop when leaving the ground. The racquet achieves its greatest speed from bouncing out of max ESR into ISR.
[..]
Since this thread is about what is and isn't true, while I personally agree with you that the legs aren't a huge power source in and of themselves and that they setup ESR and the ability to come out of that position exactly as you describe, not everyone is on precisely that page. Macci for one, as you saw really likes to focus on the legs even on young students sometimes, suggesting they JUMP on occasion - which I thought was weird - and I have to believe the guy has some clue. On the other hand he's also big on the leg drive timing with correct racquet entry into the drop, which I think most of us agree with - and I'm almost certain you do since I've seen you point out the dreaded racquet leakage to some posters on here.

Now here is Roddick's take.

Versus Taylor Dent.

Salzenstein is another great server who, while still recognising the legs, much prefers to get the upper body and the arm action correct first, and will take the legs out of it when necessary. He is more about back leg loading and coiling (a good shoulder turn away from the court).

Top Tennis Training are quite big on the concept of "power comes from the ground up" and advocate for a significant and active leg drive. Then there's Nick from Intuitive Tennis, who thinks the leg drive is completely passive.

[..]
IMO, you don’t DO a high elbow finish, it does you, kind of. The more you think of diving with power (force) from edge-to-edge through contact, the more likely you will have a straight arm. The more you snap, as quickly as possible from edge-to-edge through contact, the more you will get that elbow bend that looks like a high elbow finish
That's been precisely my experience. I will experiment with some of these things from time to time out of curiosity to see what works and what doesn't. The main motivator being to preserve the body as I age, especially since I'm defective to some extent by birth. I hear what you are saying about the high elbow finish, and I believe super fast ISR prior to contact contributes to that. Roddick, Sampras and Cilic all have very fast ISR and that elbow finish seems to be part of the result (that's what I've read anyway but I don't have the source because it was probably 6 months back). But it's not really a requirement for a great serve since there are 130mph servers on the ATP that don't do that. Neither do Serena or Ash Barty (and I rate her serve).

In the same way a really low toss with a more abbreviated or faster motion is something my body rejects. I need about a 16-18 inch drop to complete a motion that doesn't feel like I'm muscling it. That's why I'm also against the argument that a lower toss is better, and we should all aspire to be hitting at the peak. That will work for some, there is no doubt. But if it were really simply superior why do we not see it more frequently on the Tour? I believe from analysis done about 5 year ago the average WTA toss is higher than on the ATP, and the conclusion was that in general the pro women do toss higher than necessary (MaSha, are you listening???). It might be different now.

Continuing the saga.

To me that is wrong on so many levels (I do agree about Sabs).

Then there is stuff like this, which I just cannot get on board with.

You used to see that parroted all the time on here. It all goes against Brian Gordon's research, who uses the term probation (as does Macci) for placing players in a modified trophy position as their starting point in order to time the leg drive properly. Brian found that the very small speed loss (compared to a perfectly executed continuous motion) was far less significant than the damage created by mistiming the leg drive and the racquet drop. Macci uses the half serve (starting at trophy) as his number one corrective drill. They do say when players master that, it's possible to move on to some form of continuous motion, especially for the really high level juniors they're working with. But it's not necessary and a brief pause or slow down into trophy is just fine. Gordon and Macci also prefer a higher toss, as does Nick from Intuitive Tennis. I think TTT got this one right regarding the pause (imo they usually do).

So it really makes it tricky for amateurs watching good players and coaches alike delivering all sorts of contrasting messages on Youtube. Pardon the dissertation, and I hope I haven't introduced too many branches into one message. Sorry about that @Chas Tennis, but I understand where you are coming from, so it might be interesting to get some expert takes on a few of these things (to pause or not to pause, to toss at the peak, to actively jump).

#### Chas Tennis

##### G.O.A.T.
I understand what you are saying, and thanks for that explanation. Quite an interesting approach but I can see how it works. You are probably correct in your reasoning as to why, which isn't really that surprising!

Edit: I took a look at Serena using some decent footage from Essential Tennis (opposite side, but that shouldn't matter if the racquet still has the internal angle shortening the viewing perspective), and on most of those serves, using your index card approach (cool idea) there is negligible difference between the big L and a comparable frame from those above. It is hard to tell of course, but I rotated the exact same red line (hard to see sorry, but you get the picture).

Source:

Not match play, but she isn't just dinking those in, and I went for one where she followed way through on the opposite side of her body so there was a fair amount of effort.

So one other possibility is that between frames 3 and 4 there is more of an angle, and a slightly shorter racquet will appear somewhere in there. Whereas frame 4 is when I actually start to square up more (sooner than your lightbulb images). Most pro serves probably still have that slight angle even later in the motion, which also enables better use of ISR to generate more power. Having said that, Serena is almost exactly at my position and her racquet lengths are identical, so I don't know.

I really like the elbow shadow idea and will give that a whirl.
On your two Serena pictures, the baseline is at a different angle on each frame. Compare frames from one serve clip with tripod mounted camera, so that the camera is identical and the serve type is identical.

In that picture, Serena's ISR would turn the racket shaft toward the camera from Big L Position. The forearm-to-racket shaft angle is already rapidly changing at the wrist angle. When it starts IRS the forearm-to-racket shaft angle is 90ish degrees, at impact it might be 20 d..? Let's always avoid looking at just one frame and look at several frames from IRS start to impact.

Then pick the shortest racket length recorded between ISR start and impact in a high level serve. Compare that to your racket length.

A better camera angle for showing ISR is from behind, camera looking directly along the ball's trajectory.

Now we are discussing angles that are not well known in detail for ATP players because we only have internet videos that are from various camera angles and usually the type of serve is not known. We don't have control of the measurements and servers. Add to that the recording frame rate is often too low and the servers themselves have angle variations then there is uncertainty in angles for the better high level serves. All could be improved with pointing cameras.

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#### Digital Atheist

##### Hall of Fame
On your two Serena pictures, the baseline is at a different angle on each frame. Compare frames from one serve clip with tripod mounted camera, so that the camera is identical and the serve type is identical.
[..]
I guess you've never noticed that weirdness before but I have. They ARE from the same serve! Come on Chas, give me some credit please. Take another look at the stills from my serve above: the same thing happens. Also the same serve. I don't know how or why, but I've noticed the effect before when providing montages from other posters serves (side views are most noticeable) and the first time it happened I did think I'd grabbed some wrong frames. I can't explain it, but will post a video of cutting from the same serve and you can see it happening live (later).

Mine was taken on a tripod for reference.

Edit: Here you go. I forgot to turn on mouse pointer capture but you get the picture. Two frames grabbed from the last serve in that video (Cincinnati), screenshots taken using Smplayer capture (no manual selections to avoid any misalignment issues). Both screenshots placed into GIMP and then the second is overlaid onto the first and moved sideways. Now, if anyone can explain this phenomena and why it happens (like I said, my frames above do exactly the same thing) then I'd like to hear it?

A better camera angle for showing ISR is from behind, camera looking directly along the ball's trajectory.
Yeah for sure, and I'll go with some tape on the arm as I believe you've suggested in the past, just to see what happens. It's a nice day here atm so I should be able to get something this arvo and report back.

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#### Chas Tennis

##### G.O.A.T.
They ARE from the same serve! Come on Chas, give me some credit please. Take another look at the stills from my serve above: the same thing happens as with Serena. Also the same serve. I don't know how or why that happens, but I've noticed the effect before when providing montages from other posters serves (side views are most noticeable) and the first time it happened I did think I'd grabbed some wrong frames. I can't explain it, but will post a video of cutting from the same serve and you can see it happening live (later).

Mine was taken on a tripod for reference.
The angle of the baseline looks different in each frame? ??

#### Digital Atheist

##### Hall of Fame
The angle of the baseline looks different in each frame? ??
I just posted a video above as an edit of the 2 frames taken from the same Serena serve. It is a live screen recording so you can see for yourself and the mind can warp even more! This happens on side views all the time, like I said. Strange fruit indeed.

So I tried the tape on my arm and used a tripod for camera placement as close as I could comfortably get it. I think light grey 100mph tape was a bad choice and almost worthy of a YT fail video! It shows fine on my arm, but is really difficult to see on the serve with shadows and what not. However, I can just make it out when I blow it up to 200%, so I have drawn red lines over the tape so you can see.

I don't know how useful that is or how much ISR there is supposed to be. I might paint it red next time.

Here is an image of my TP (one frame before I can see my legs start to push as best I can tell). That's an example of why imo side views are horrid for judging elbow positions, since that's close enough to straight through the shoulder line for me. It didn't used to be, but I've continued to obsess over that aspect even after I worked on it and now I can let it go. I guess we all have our obsessions.

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#### Digital Atheist

##### Hall of Fame
The serve is more like a shot put than a throwing motion - Meike Babel is on board with that analogy and she could play a bit. But is it true? Dr. Mark Kovacs - a well renowned sports scientist and excellent tennis player - is one of the pioneers of this concept if I'm not mistaken, so I guess there is some basis.

I just don't see it or feel it when I'm serving, and don't know how it could even be useful. That's just me, and I might be in the minority.

Imo this is the action you want, demonstrated by Patrick M where at 16 seconds and he says "the elbow comes in front as the hand goes down".

I feel like the shot put cue for a lot of rec players could result in going straight up from the trophy position (as Meike demonstrates) skipping that vital component, and they will have NO ESR and a terrible racquet drop, among other things. What is so wrong with learning to throw UP, for height and not distance?

The term Dr Kovacs uses is long axis rotation, where it all happens as part of one larger movement (including the shoulder). Now that I can understand.

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#### Chas Tennis

##### G.O.A.T.
IMO, ISR happens TO the shoulder, it is not performed BY the shoulder.
ISR - Internal Shoulder Rotation
It is performed by the shoulder joint.

When we are lucky enough to have a defined term - useful for discussing tennis strokes - please read the definition.

Joint motions are defined by bone movements at the joint regardless of cause.

Some causes;
1) Active muscle forces - brain sends signal to shorten muscle, shortens muscles and moves joint.
2) Passive muscle forces- stretched muscles shorten to cause joint motions.
3) Moving other body parts - causes inertial forces on joint body parts & changes joint angles.
4) Any other causes of joint motions.
5) Any combination of the above causes.

It lacks detail to sum up 1-5 and call it simply "performed".

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