Why can't I get lateral spin on my (tentative) kick serve ? (With video)

Chas Tennis said:

Many threads involve discussions between posters using undefined terms.
1) If you know your use of the term is defined, please provide a Google link to that meaning if asked.
2) If not defined, please explain each time that your use the term, your individual usage.

The main problem in using conservational terms in technical discussions is loose meaning, ambiguous or misleading, etc. But worse is using the same exact terms, such as "pronation" and "actively". These terms have established definitions and wide use in biomechanics and kinesiology, to describe other joint motions or other muscle actions with a completely different meaning known only to the user but not to the readers.

The word "actively" is very often used on the forum in ways that are different than for the Hill Muscle Model's defined use of actively. Ballmachineguy - what do you mean by "actively".

We should have an award each year.

Tower of Babel - Wikipedia

en.wikipedia.org

Many forum threads have many posts where posters are arguing over their individual thoughts about terms. You can find similar threads and discussions from 10 years ago..........

With high speed videos or by using defined terms, issues can be settled on the biomechanics of tennis strokes. .............then move on to more interesting discussions.

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By “actively” I mean using it to control hitting the ball (direction and speed). If you look at a serve (suggest using a pro player) at the lowest racquet drop, it doesn’t even look like a position you could use muscle to either get into or out of. Whether they are used at 5%, 20% or some other value before around 90* angle, the shoulder muscles are not responsible for taking the racquet from trophy through drop, and starting up to the ball. Anyway, it is only common sense that one wouldn’t want to contract their muscles at full-stretch when the point of stretching them (via drop and leg drive) is to have them catapult back up. How would bending the knees and pushing from the ground even assist the serve if your shoulder was contracting and guiding the racquet through the stroke? The only benefit of the jump would be the mph jumping contributes, maybe 2 mph.

ballmachineguy said:

Yeah, the shoulder obviously has to be used to get the racquet to that point. I was talking post-trophy.

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That point in the photo is already way after trophy. I meant how did the elbow go up there after trophy? Just by gravity and leg drive? ( because you said shoulder and arm muscles should start working from that point on, not before )

Curious said:

That point in the photo is already way after trophy. I meant how did the elbow go up there after trophy? Just by gravity and leg drive? ( because you said shoulder and arm muscles should start working from that point on, not before )

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Sorry! I get it.
Ok, you toss, left arm goes up right shoulder down with right elbow in line with those, so it is lower. When it is time to attack ball, you are rotating the torso. That is what gets the right shoulder up, left shoulder down, and, since the elbow was in line with them, it is now above them.

ballmachineguy said:

Sorry! I get it.
Ok, you toss, left arm goes up right shoulder down with right elbow in line with those, so it is lower. When it is time to attack ball, you are rotating the torso. That is what gets the right shoulder up, left shoulder down, and, since the elbow was in line with them, it is now above them.

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We’re still not on the same page.
Let me ask this way, when exactly do you start your explosive upward swing? At trophy/ a little after trophy/ way after trophy ( say when the racket is already coming to the bottom of drop ) ?

Curious said:

We’re still not on the same page.
Let me ask this way, when exactly do you start your explosive upward swing? At trophy/ a little after trophy/ way after trophy ( say when the racket is already coming to the bottom of drop ) ?

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Wow. We apparently aren’t on the same page yet. Maybe my 4th glass of red wine is contributing. Legal to drink and post?
Anyhow, let’s assume we have achieved trophy position and go from there. Whether one pauses or lets the racquet head swing through the trophy phase (delayed armers) that is the real start of the serve. The knees are already bent, you just allow gravity to drop the racquet, the legs extend pushing the racquet down further than it otherwise could go, and, at the same time, the torso rotates. All of these things throw the racquet up over your head. As acceleration is paramount to any stroke, you then feed your muscles (arm, shoulder) in to finish the stroke.
I will try some serves tomorrow where I use my arm muscles to go from trophy phase to hitting the ball and see how it goes. If it is better than how I described, I will retract everything I’ve said. I don’t see how it would be better forcing it to go places all the other movements are taking it anyway.

ballmachineguy said:

Wow. We apparently aren’t on the same page yet. Maybe my 4th glass of red wine is contributing. Legal to drink and post?
Anyhow, let’s assume we have achieved trophy position and go from there. Whether one pauses or lets the racquet head swing through the trophy phase (delayed armers) that is the real start of the serve. The knees are already bent, you just allow gravity to drop the racquet, the legs extend pushing the racquet down further than it otherwise could go, and, at the same time, the torso rotates. All of these things throw the racquet up over your head. As acceleration is paramount to any stroke, you then feed your muscles (arm, shoulder) in to finish the stroke.
I will try some serves tomorrow where I use my arm muscles to go from trophy phase to hitting the ball and see how it goes. If it is better than how I described, I will retract everything I’ve said. I don’t see how it would be better forcing it to go places all the other movements are taking it anyway.

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Interesting you say that. I also was thinking of serving tomorrow the way you described it as I’m really curious as to how that will feel.

ballmachineguy said:

By “actively” I mean using it to control hitting the ball (direction and speed). If you look at a serve (suggest using a pro player) at the lowest racquet drop, it doesn’t even look like a position you could use muscle to either get into or out of. Whether they are used at 5%, 20% or some other value before around 90* angle, the shoulder muscles are not responsible for taking the racquet from trophy through drop, and starting up to the ball. Anyway, it is only common sense that one wouldn’t want to contract their muscles at full-stretch when the point of stretching them (via drop and leg drive) is to have them catapult back up. How would bending the knees and pushing from the ground even assist the serve if your shoulder was contracting and guiding the racquet through the stroke? The only benefit of the jump would be the mph jumping contributes, maybe 2 mph.

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High speed video observations of tennis strokes of ATP players are a creditable source of serve information.

Research on the serve that occurred between 1995 and the early 2000's provided a biomechanical model, the most creditable source. That model for the serve is being used and improved today. I have posted many times using their model and my better described and illustrated posts are from about 5 years ago.

There are many references. Search: B. Elliott, Marshall, Crespo, Reid, tennis serve, internal shoulder rotation

If you put a limited amount of time searching and reading what is out there you would see what we have been discussing on the forum for the last few years.

My view of the serve and its sub-motions is based, for example, on The Biomechanics of Advanced Tennis, 2003, editors B. Elliot, Reid, Crespo. This reference was accepted and published by the ITF for many years. $275 for many years, now out of print, the used price is not cheap. It provides a logical breakdown of the serve where you can see the sub-motions that are discussed, "leg thrust", "shoulder-over-shoulder" (Cartwheel) , "trunk twist", "somersault" and some others. Most of the sub-motions for the serve, pre stretch muscles especially the muscles that perform internal shoulder rotation.

They used a term "maximum external shoulder rotation" (MER). Stick your upper arm straight out to the side of your shoulder, 90 d. elbow bend, racket & hand up, comfortable grip and angle of forearm to racket shaft. Bend it back and observe the tendency for it to drop from gravity. Not much. Rapidly accelerating the shoulder can cause the inertia of the arm and racket to cause additional external shoulder rotation (ESR). That is one thing the leg thrust does. ESR causes the internal shoulder muscles (ISR) to stretch. Other things are going on. The stretched ISR muscles are used "passively" for ISR, the joint muscle that adds the most to racket head speed. In the Hill Muscles Model 'passive' is used for elastic forces and 'active' is used for the forces that are produced by nerve signals sent to Actin & Myosin in sarcomeres. Take your hand and actively move the wrist toward little finger - toward thumb, it's slow. Now gently shake your hand side-to-side with forearm motion so that your fingers appear blurred. That is passive with maybe some active? When my fingers are shaking and blurry in front of my eyes, I am not actively or consciously sending the same nerve signals as when I do active motions.

For the racket drop, after getting much ESR, the wrist can allow the racket to drop farther. In other problems, I've estimated the time it takes an object to fall from gravity. Gravity has been slower than the motions I observed in videos, so I do not assume that gravity does the job. These comments simplify the real problem. Search: time falling body gravity graph pictures

In a tennis stroke the arm is supported at the shoulder and free at the hand, so the fall time of gravity in the above grap does not apply. You can take a racket and place it in positions seen in serve videos, hold it and quickly relax your wrist muscles. The racket will drop. Take a video and compare that time to what you see during the serve's racket drop. Hold your arm straight out from your shoulder and let it drop. Time that. Try some experiments to see how fast gravity moves the arm and racket.

Digital Atheist said:

...

I'm afraid you haven't been clear there! An award for what specifically?

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The Tower of Babel and its story is about many peoples building a tower together, but they speak many different languages. The Tower of Babel represents the 16 years of forum posts where the terms used by posters might mean this or might mean that to the readers.

We could have annual forum awards, in the shape of that painting tower, for the posters that use undefined terms in the spirit of the Tower of Babel.

Chas Tennis said:

High speed video observations of tennis strokes of ATP players are a creditable source of serve information.

Research on the serve that occurred between 1995 and the early 2000's provided a biomechanical model, the most creditable source. That model for the serve is being used and improved today. I have posted many times using their model and my better described and illustrated posts are from about 5 years ago.

There are many references. Search: B. Elliott, Marshall, Crespo, Reid, tennis serve, internal shoulder rotation

If you put a limited amount of time searching and reading what is out there you would see what we have been discussing on the forum for the last few years.

My view of the serve and its sub motions is based, for example, on The Biomechanics of Advanced Tennis, 2003, editors B. Elliot, Reid, Crespo. This reference was accepted and published by the ITF for many years. $275 for many years, now out of print, the used price is not cheap. It provides a logical breakdown of the serve where you can see the sub-motions that are discussed, "leg thrust", "shoulder-over-shoulder" (Cartwheel) , "trunk twist", "somersault" and some others. Most of the sub-motions for the serve, pre stretch muscles especially the muscles that perform internal shoulder rotation.

They used a term "maximum external shoulder rotation" (MER). Stick your upper arm straight out to the side of your shoulder, racket & hand up, comfortable grip and angle of forearm to racket shaft. Bend it back and observe the tendency for it to drop from gravity. Not much. Rapidly accelerating the shoulder can cause the inertia of the arm and racket to cause additional external shoulder rotation (ESR). That is one thing the leg thrust does. ESR causes the internal shoulder muscles (ISR) to stretch. More goes on. The stretched ISR muscles are used "passively" for ISR, the joint muscle that adds the most to racket head speed. In the Hill Muscles Model 'passive' is used for elastic forces and 'active' is used for the forces that are produced by nerve signals sent to Actin & Myosin in sarcomeres. Take your hand and actively move the wrist toward little finger - toward thumb, it's slow. Now gently shake your hand side-to-side with forearm motion so that your fingers appear blurred. That is passive with maybe some active? When my fingers are shaking and blurry in front of my eyes, I am not actively or consciously sending the same nerve signals as when I do active motions.

For the racket drop, after getting much ESR, the wrist can allow the racket to drop farther. In other problems, I've estimated the time it takes an object to fall from gravity. Gravity has been slower than the motions I observed in videos, so I do not assume that gravity does the job. This simplifies the problem. Search: time falling body gravity graph pictures

You can take a racket and place it in positions seen in serve videos, hold it and quickly relax your wrist muscles. The racket will drop. Take a video and compare that time to what you see during the serve's racket drop. Hold your arm straight out from your shoulder and let it drop. Time that. Try some experiments to see how fast gravity moves the arm and racket.

Click to expand...

I started to get the bedtime sillies reading that entire post. Yes, muscles are used to get the racquet to drop, but they are not in the arm. They are the core muscles. As your left shoulder drops and the right shoulder goes up this causes the racquet to swivel and get pushed down with more force than just gravity. Also, as mentioned before, the leg drive forces it down faster. But, as far as the arm is concerned, it only needs to allow it to drop. Try and get it down there with arm muscles, and your shoulder muscles must contract also, slowing your swing. I will print that and only charge postage for anyone that wants it. Save everybody $275.

Curious said:

Interesting you say that. I also was thinking of serving tomorrow the way you described it as I’m really curious as to how that will feel.

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I tried serving today with guiding my arm through its circuit deliberately. No waiting to drop or start up, and while it wasn’t terrible, I lost some mph.

Chas Tennis said:

The Tower of Babel and its story is about many peoples building a tower together, but they speak many different languages. The Tower of Babel represents the 16 years of forum posts where the terms used by posters might mean this or might mean that to the readers.

We could have annual forum awards, in the shape of that painting tower, for the posters that use undefined terms in the spirit of the Tower of Babel.

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OK fair enough. I am vaguely familiar with the Tower of Babel, but didn't see how it related to awards on a tennis forum. "Active" is a well defined term and I don't see how the previous usage was confusing for you. Likewise, actual use affects definitions in certain contexts, so "pronation" and "full pronation" as they relate to the tennis serve are, in my estimation, quite well understood and used in a consistent manner by most people on this forum. Obviously that is purely anecdotal and I could well be wrong.

ballmachineguy said:

I tried serving today with guiding my arm through its circuit deliberately. No waiting to drop or start up, and while it wasn’t terrible, I lost some mph.

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And I tried what I thought you were talking about.
I tried to delay the start of explosive phase. I had to go through the trophy position more quickly to get the timing right. I don’t think I lost power. The whole serve seems to have sped up but I feel some sort of smoothness although it looks more rushed now. Strange.

Digital Atheist said:

OK fair enough. I am vaguely familiar with the Tower of Babel, but didn't see how it related to awards on a tennis forum. "Active" is a well defined term and I don't see how the previous usage was confusing for you. Likewise, actual use affects definitions in certain contexts, so "pronation" and "full pronation" as they relate to the tennis serve are, in my estimation, quite well understood and used in a consistent manner by most people on this forum. Obviously that is purely anecdotal and I could well be wrong.

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The research on tennis biomechanics has grown beyond how "most people on this forum" think. The ground breaking research on the serve was published 25 years ago. Pronation was shown to be much less and internal shoulder rotation was shown to be much more important.

Tennis jargon for strokes has been shown on many/most occasions to be misleading and inconsistent with high speed videos and research.

Would you recommend that a young person learn some biomechanics and its terms or what "most people on this forum" think?

We are living in the Dark Ages of the new Information Age - where cut and paste of bad information often smothers good information.

Chas Tennis said:

Would you recommend that a young person learn some biomechanics and its terms or what "most people on this forum" think?

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Young persons should learn to move well and hit the ball well. What they do quite well. Do you think Yannik Sinner is deep into biomechanics? Do you think he would play better if he was?

Chas Tennis said:

Would you recommend that a young person learn some biomechanics and its terms or what "most people on this forum" think?

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No, but I also wouldn't recommend anyone trying to improve their tennis game worry about an entire scientific field; the technically correct term or definition for some prescribed joint motion is, for the most part, completely irrelevant to the tennis player. I'm going to assume that wasn't a strawman, since pronation on the tennis serve is simply turning the forearm from approximately the big L when the racquet is on edge so that the "strings square up" at contact. Full pronation or pronation post contact is the continued turning of the forearm so that the strings face outward. If you think that is incorrect or somehow problematic despite the fact this is how I have seen it used repeatedly both here and in various other sources, then we can agree to disagree.

That's not to say there isn't value in applying advanced biomechanics to the analysis of high level tennis strokes, primarily for the purposes of furthering understanding so that it can aid in the teaching process, but it is next to useless for the actual player.

Dragy said:

Young persons should learn to move well and hit the ball well. What they do quite well. Do you think Yannik Sinner is deep into biomechanics? Do you think he would play better if he was?

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You beat me to it.

ballmachineguy said:

I tried serving today with guiding my arm through its circuit deliberately. No waiting to drop or start up, and while it wasn’t terrible, I lost some mph.

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Why not flatter us with a viewing experience?

Dragy said:

Young persons should learn to move well and hit the ball well. What they do quite well. Do you think Yannik Sinner is deep into biomechanics? Do you think he would play better if he was?

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I believe that nearly all pro tennis players have received extensive instruction from knowledgeable instructors. The next generation of techniques - I'd guess - is still being discovered by high performance players. ?

Digital Atheist said:

................................., since pronation on the tennis serve is simply turning the forearm from approximately the big L when the racquet is on edge so that the "strings square up" at contact. .................................

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This is the problem. This communication is not correct and misleads readers.

Dragy, what do you think?

Chas Tennis said:

This is the problem. This communication is not correct and misleads readers.

Dragy, what do you think?

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Mislead readers? Possibly. But on court, followed by demonstration, it might be good enough to give an entrance point for further training and mastering the serve.
I personally hate all the talks about wrist with regard to serves or forehands. But I'm sure most competent coaches can demonstrate what they want student to execute, and set up some drills and exercises to ingrain proper things. Particularly with young players, it appears 10 times more effective than any descriptions, whatever precise and correct they were.

Chas Tennis said:

Would you recommend that a young person learn some biomechanics and its terms or what "most people on this forum" think?

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I’d recommend they’d do neither

Chas Tennis said:

I believe that nearly all pro tennis players have received extensive instruction from knowledgeable instructors.

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And I can almost guarantee those instructors never used precise biomechanical terminology to get their points across or cue the correct movement patterns

Dragy said:

Mislead readers? Possibly. But on court, followed by demonstration, it might be good enough to give an entrance point for further training and mastering the serve.
I personally hate all the talks about wrist with regard to serves or forehands. But I'm sure most competent coaches can demonstrate what they want student to execute, and set up some drills and exercises to ingrain proper things. Particularly with young players, it appears 10 times more effective than any descriptions, whatever precise and correct they were.

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I was talking about communication by written posts on the forum and the use of 'pronation' when internal shoulder rotation is the correct joint motion.

Interested readers can Google: internal shoulder rotation and then they have it from then on.

If your are on a court and the instructor says "pronation" how do your know what is meant or if they understand?

Chas Tennis said:

I was talking about communication by written posts on the forum and the use of 'pronation' when internal shoulder rotation is the correct joint motion.

Interested readers can Google: internal shoulder rotation and then they have it from then on.

If your are on a court and the instructor says "pronation" how do your know what is meant or if they understand?

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Yeah, that seems to be an issue. Most try to talk about improving their tennis, while you keep talking about communication by written posts. Most find their way through and deliver piece of advice. Sometimes it’s via several posts back and forth, sometimes by extra participants joining. The goal is to make the one asking try some things on court which might help him improve - not to publish an ultimately precise biomechanical description.

Dragy said:

...
The goal is to make the one asking try some things on court which might help him improve - not to publish an ultimately precise biomechanical description.

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Where do you get that stated goal from?
Are you really claiming that as a truth all through the forum?
Did you read the OP of this thread saying; "I'd be glad to read technical advices." ? (https://tt.tennis-warehouse.com/ind...ve-kick-serve-with-video.654327/post-13773713)

#fwiw

I gave up on a kick seven years ago

kaninfaan said:

Did you read the OP of this thread saying; "I'd be glad to read technical advices." ?

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I don't think that specifically is the issue here. Technical advice can be useful and @Chas Tennis at one point made an interesting observation about my old serve which I found useful (and he has since discovered there are many pro servers who don't have the classic trophy position like Fed where the strings perfectly face the side before going into the racquet drop).

There are several posters here who do delve into technical aspects and I think they do so quite well. But I believe the problems seem to arise when the words used to deliver that advice (words that are generally well accepted and defined based on dictionary AND usage both here and in the tennis community at large) regularly become questioned.

Now, getting out the protractor and measuring precise angles versus a particular pro, that's probably a bit much IMO.

Maybe we need a sticky with a detailed Chas thread defining various joint motions and other movements used in the game of tennis. He could also include that frame by frame serve image by Toly (??) with a description. Then we can debate the terminologies, hopefully reach a general consensus, and use that as a reference for further discussion and posting? This is a serious suggestion in case anyone thinks I'm trolling.

Chas Tennis said:

If your are on a court and the instructor says "pronation" how do your know what is meant or if they understand?

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That’s the thing. No instructor is going to use that term on court. Likewise, no instructor would use “internal shoulder rotation” on court and expect anyone to understand

Curious said:

And I tried what I thought you were talking about.
I tried to delay the start of explosive phase. I had to go through the trophy position more quickly to get the timing right. I don’t think I lost power. The whole serve seems to have sped up but I feel some sort of smoothness although it looks more rushed now. Strange.

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I guess smooth is good.

Chas Tennis said:

If your are on a court and the instructor says "pronation" how do your know what is meant or if they understand?

Click to expand...

yossarian said:

That’s the thing. No instructor is going to use that term on court. Likewise, no instructor would use “internal shoulder rotation” on court and expect anyone to understand

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Probably not, but for arguments sake let's assume an instructor does use the term pronation (you see it used a fair amount on YouTube by the likes of Salzenstein and Simon & Alex from Top Tennis Training and others with at least *some* pedigree). They would simply demonstrate it to the student while explaining (this is pronation, where the forearm turns and squares the strings up to the ball, then after contact the forearm continues its path and turns out even more). To some extent, a demonstration by the coach is always going to be useful in clarifying, no matter what terms are being used. The coaches job in part is to make sure the student understands. Here's an example of breaking down the serve and teaching the different components (they see, they copy, you help and assist in making sure they are doing the movements correctly):


@Chas Tennis: given your current argument, how would you know for sure they understood anything being explained to them? They'd need a dictionary, a protractor, and an expert in biomechanics before they even stepped on the court. Not practical.

Digital Atheist said:

Probably not, but for arguments sake let's assume an instructor does use the term pronation (you see it used a fair amount on YouTube by the likes of Salzenstein and Simon & Alex from Top Tennis Training and others with at least *some* pedigree). They would simply demonstrate it to the student while explaining (this is pronation, where the forearm turns and squares the strings up to the ball, then after contact the forearm continues its path and turns out even more). To some extent, a demonstration by the coach is always going to be useful in clarifying, no matter what terms are being used. The coaches job in part is to make sure the student understands. Here's an example of breaking down the serve and teaching the different components (they see, they copy, you help and assist in making sure they are doing the movements correctly):

@Chas Tennis: given your current argument, how would you know for sure they understood anything being explained to them? They'd need a dictionary, a protractor, and an expert in biomechanics before they even stepped on the court. Not practical.

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The majority of internet tennis instructional videos avoid mentioning internal shoulder rotation - that is also the problem. By not mentioning internal shoulder rotation it hides the most significant joint motion used for the tennis serve and leaves it to the viewer to somehow figure it out. That's wrong. Do you want an instructor to hide the biomechanics of the serve? Leave out what is true? What is the plus side of that?

NOTE- to get sounds on my videos I have to click on Youtube and view it there. Always also use full screen.

Joint Motions of Pronation vs Internal Shoulder Rotation
Notice the small muscles that are used for pronation.

Here is another serving video were the instructor describes internal shoulder rotation and says it. It's accurate.

Kinesiology is the study of the body's joint motions and the muscles that perform those motions.
Internal Shoulder Rotation (forearm goes along for the ride)

Chas Tennis said:

The majority of internet tennis instructional videos avoid mentioning internal shoulder rotation - that is also the problem. By not mentioning internal shoulder rotation it hides the most significant joint motion used for the tennis serve and leaves it to the viewer to somehow figure it out. That's wrong. Do you want an instructor to hide the biomechanics of the serve? Leave out what is true? What is the plus side of that?

Joint Motions of Pronation vs Internal Shoulder Rotation

Notice the small muscles that are used for pronation.

Here is another serving video were the instructor describes internal shoulder rotation and says it. It's accurate.

Kinesiology is the study of the body's joint motions and the muscles that perform those motions.
Internal Shoulder Rotation (forearm goes along for the ride)

Click to expand...

Did you see my suggestion in this earlier previous post? I think that might be worthwhile considering. Then it can all be hashed out and used as a reference. Also, that way no one can beat you up for any potential "paralysis by analysis", since it would be a thread dedicated purely to the biomechanics of tennis strokes.

Chas Tennis said:

The majority of internet tennis instructional videos avoid mentioning internal shoulder rotation - that is also the problem. By not mentioning internal shoulder rotation it hides the most significant joint motion used for the tennis serve and leaves it to the viewer to somehow figure it out. That's wrong. Do you want an instructor to hide the biomechanics of the serve? Leave out what is true? What is the plus side of that?

Joint Motions of Pronation vs Internal Shoulder Rotation

Notice the small muscles that are used for pronation.

Here is another serving video were the instructor describes internal shoulder rotation and says it. It's accurate.

Kinesiology is the study of the body's joint motions and the muscles that perform those motions.
Internal Shoulder Rotation (forearm goes along for the ride)

Click to expand...

Again, I don’t think you’re understanding the point here.

Take your average tennis player who is taking lessons. An instructor tells them “now listen here. The key to the high level serve is internal shoulder rotation”

Student: Huh?

Instructor: Medial rotation of the humerus within the glenoid fossa

Student: ...huh?

Instructor: Go read up on kinesiology and you’ll understand

Student: yeah I’m not going to do that. Wait, you so mean turn your arm down like this?

Instructor: What is “down?” What is “arm?” No, we must only use technically correct, defined language.

Student: I’m finding a new teacher

yossarian said:

...

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Since Im the one responsible for this thread-drift I'll get @Digital Atheist @Chas Tennis and @Dragy in here as well.

In @yossarian 's example above I think we all agree that the instructor wouldnt talk like that. But a (hopefully) probable version would be:
<--
Take your average tennis player who is taking lessons. An instructor tells them “now listen here. The key to the high level serve is the shoulder”

Student: Huh?

Instructor: - maintaining a stable shoulder while rotating the arm like this (waving in the air)

Student: Aha! I heard some guys who looked really cool talk about pronation? and snapping(?) the wrist?

Instructor: There's a whole lot of bro-science going around where they apropriate a technical term to make themselves sound good.

Student: Yeah, ok. Ive stumbled upon that in the gym as well.

Instructor: Anyhow, concentrate on a stable shoulder for now. Here, try this...
-->
Imho this forum can either be a force for good or increase the confusion. Therefore, using proper terminology instead of bro-science is a good thing.
On teh interwebz people can look things up, unlike Yossarian 's example above.

"The nothing itself nihilates"
- Martin Heidegger (1889-1976)

"Trying is the first step towards failure."
- Homer Simpson

#nomenclature #fwiw #imho #1337

Digital Atheist said:

I don't think that specifically is the issue here. Technical advice can be useful and @Chas Tennis at one point made an interesting observation about my old serve which I found useful (and he has since discovered there are many pro servers who don't have the classic trophy position like Fed where the strings perfectly face the side before going into the racquet drop).

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Whoah. Please, always directly quote when you say what others think. I do not recognize what you say I "discovered".

Digital Atheist said:

There are several posters here who do delve into technical aspects and I think they do so quite well. But I believe the problems seem to arise when the words used to deliver that advice (words that are generally well accepted and defined based on dictionary AND usage both here and in the tennis community at large) regularly become questioned.

Click to expand...

I have issues with forum posters in discussions about stroke biomechanics, especially whenever the same terms, that are defined and widely used in biomechanics, are incorrectly used in posts to describe tennis strokes. 'Pronation' vs internal shoulder rotation during the serve is the flagship of incorrect and misleading usage for all readers. Each day "pronation" is incorrectly used a hundred times more often than "internal shoulder rotation" is used, so the contagion spreads...... You can't Google a definition of pronation and get its tennis usage. Also, I get into many disagreements when posters say something that I confirm disagrees with high speed video observations.

Digital Atheist said:

Now, getting out the protractor and measuring precise angles versus a particular pro, that's probably a bit much IMO.

Maybe we need a sticky with a detailed Chas thread defining various joint motions and other movements used in the game of tennis. He could also include that frame by frame serve image by Toly (??) with a description. Then we can debate the terminologies, hopefully reach a general consensus, and use that as a reference for further discussion and posting? This is a serious suggestion in case anyone thinks I'm trolling.

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I have posted high speed videos with labels for joint angles and posted links to definitions. Anyone that does not understand a term that I use can almost always Google it and get a clear answer in a minute, plus demo videos, and videos on how to measure joint angles. All the academic information can be Googled. But readers can't Google the term if used with a poster's personal meaning.

Analysis of body motions has already been developed for us, starting with the Greeks and Romans. It is based first on bones and joints. Each bone, muscle and joint has a name and has been defined in an unambiguous way for use in scientific literature. If each poster sets their own definition and then uses the same scientific term incorrectly, it muddles communication. Basically, the posts here have become more biomechanical and that is when the terms have to leave behind the familiar conversational terms and meanings and especially junk incorrect meanings while using the defined scientific terms, as for pronation during the tennis serve.

The Figures behind the Birth of Knowledge of Biomechanics - ISB Glasgow

Have you heard of the word “biomechanics”? Probably, you have encountered this term from a sports injury specialist. The science

www.isbglasgow.com

.

Chas Tennis said:

Whoah. Please, always directly quote when you say what others think. I do not recognize what you say I "discovered"

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That's a fair request that just isn't always possible; based on sheer quantity of posts and elapsed time, sometimes it simply isn't worth the effort; however, I will point you to Jack Sock (Iirc he was one of the servers that you referenced, but the problem is I could be wrong since I also don't remember exactly what words were used!). Observe the angle of his racquet as he takes it up and through trophy (and how the strings face the back fence for the most part). But anyway, if you don't remember then no worries, we can both forget I ever said it!

EDIT: Here is one of the references, (I believe there was another and will look for it later):

kaninfaan said:

Since Im the one responsible for this thread-drift I'll get @Digital Atheist @Chas Tennis and @Dragy in here as well.

In @yossarian 's example above I think we all agree that the instructor wouldnt talk like that. But a (hopefully) probable version would be:
<--
Take your average tennis player who is taking lessons. An instructor tells them “now listen here. The key to the high level serve is the shoulder”

Student: Huh?

Instructor: - maintaining a stable shoulder while rotating the arm like this (waving in the air)

Student: Aha! I heard some guys who looked really cool talk about pronation? and snapping(?) the wrist?

Instructor: There's a whole lot of bro-science going around where they apropriate a technical term to make themselves sound good.

Student: Yeah, ok. Ive stumbled upon that in the gym as well.

Instructor: Anyhow, concentrate on a stable shoulder for now. Here, try this...
-->
Imho this forum can either be a force for good or increase the confusion. Therefore, using proper terminology instead of bro-science is a good thing.
On teh interwebz people can look things up, unlike Yossarian 's example above.

"The nothing itself nihilates"
- Martin Heidegger (1889-1976)

"Trying is the first step towards failure."
- Homer Simpson

#nomenclature #fwiw #imho #1337

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That's why I tried to post a video of an actual example (assuming McCraw also wouldn't use the word pronation with the kids, and I don't think he would).

If ISR does happen and I’m not sure much does, my forearm rotates much more. Seems to happen at the elbow. Regardless, it (ISR) is the result of what I do with my hand. I certainly wouldn’t try and get someone to do with the racquet what needs to happen in the serve by telling them to rotate their shoulder as it would be totally ineffective. The reason it is hard to find videos that mention ISR may not be because people are teaching incorrectly or leaving out important information.

ballmachineguy said:

If ISR does happen and I’m not sure much does, my forearm rotates much more. Seems to happen at the elbow. Regardless, it (ISR) is the result of what I do with my hand. I certainly wouldn’t try and get someone to do with the racquet what needs to happen in the serve by telling them to rotate their shoulder as it would be totally ineffective. The reason it is hard to find videos that mention ISR may not be because people are teaching incorrectly or leaving out important information.

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Demo of Pronation (defined joint motion). Take a racket in your hand, wrist neutral. Have your elbow at 90 degrees. Now when you do pronation and supination, the forearm between the elbow and hand will rotate back and forth driven by the muscles that do pronation and supination. The racket will swing back & forth. The muscles that do pronation are smaller muscles in the forearm.

Demo of Internal Shoulder Rotation. Take a racket in the hand as above, neutral wrist. Have your elbow straight. Now rotate the near straight arm from the shoulder. Try to not twist the forearm with any pronation. That is internal shoulder rotation and it is driven by the lat, pecs and some other shoulder muscles. The racket will swing back & forth and move like pronation. These ISR muscles are much larger than the forearm muscles that do pronation.

Now try to estimate the power of these two joint motions, pronation vs internal shoulder rotation. Safely rotate the wrist and racket with pronation & elbow bent at 90 degrees and then with internal shoulder rotation arm near straight, get some speed. I'm worried about asking you to get sound from the racket head and air. The muscles are shortening with active forces from Actin & Myosin.

The larger muscles of ISR will be capable of more power than the smaller forearm muscles of pronation.

For the serve, many of the sub-motions stretch the muscles that perform ISR. The muscles are like giant rubber bands ready to perform ISR very rapidly. I don't know what releases the pre-stretched muscles to start ISR. For ISR alone the near straight arm does not go anywhere, it stays in place, it just spins like a top. The bone that is driven is the humerus.

Chas Tennis said:

Demo of Pronation (defined joint motion). Take a racket in your hand, wrist neutral. Have your elbow at 90 degrees. Now when you do pronation and supination, the forearm between the elbow and hand will rotate back and forth driven by the muscles that do pronation and supination. The racket will swing back & forth. The muscles that do pronation are smaller muscles in the forearm.

Demo of Internal Shoulder Rotation. Take a racket in the hand as above, neutral wrist. Have your elbow straight. Now rotate the near straight arm from the shoulder. Try to not twist the forearm with any pronation. That is internal shoulder rotation and it is driven by the lat, pecs and some other shoulder muscles. The racket will swing back & forth and move like pronation. These ISR muscles are much larger than the forearm muscles that do pronation.

Now try to estimate the power of these two joint motions, pronation vs internal shoulder rotation. Safely rotate the wrist and racket with pronation & elbow bent at 90 degrees and then with internal shoulder rotation arm near straight, get some speed. I'm worried about asking you to get sound from the racket head and air. The muscles are shortening with active forces from Actin & Myosin.

The larger muscles of ISR will be capable of more power than the smaller forearm muscles of pronation.

For the serve, many of the sub-motions stretch the muscles that perform ISR. The muscles are like giant rubber bands ready to perform ISR very rapidly. I don't know what releases the pre-stretched muscles to start ISR. For ISR alone the near straight arm does not go anywhere, it stays in place, it just spins like a top. The bone that is driven is the humerus.

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Serious question: do you read the comments you reply to and say “hmm...let me cut and paste a stock response to this?”

You literally said nothing really related to anything he wrote

He didn’t say he was confused about the joint motions. He just said that he feels his forearm rotates more during the serve, which is driven by rotation that first occurs at his shoulder

I don’t know if this is technically true, but it is logically sound. In a closed kinetic chain task (I consider the serve to be closed chain even though the distal extremity is free to move — motion is occurring at multiple joints and they are all influenced by one another), internal shoulder rotation and pronation are COUPLED. It’s not either or. It’s AND

Now again, I don’t know if what he said is accurate about the amount of rotation he gets at one joint or the other. But instead of addressing that, you cut and paste a stock comment about defining joint motions and power potential from the muscles used. All at best tangentially related to his post

And again, you seem to be missing the main point of his post. It’s not that ISR isn’t occurring, it’s that it just does without conscious attention devoted to driving it. So nobody but biomechanically inclined people are going to mention it in instruction. Knowledge of the process has no tangible benefit to most tennis players, especially when you have found no way to cue it aside from “watch high speed video”

Chas Tennis said:

Demo of Pronation (defined joint motion). Take a racket in your hand, wrist neutral. Have your elbow at 90 degrees. Now when you do pronation and supination, the forearm between the elbow and hand will rotate back and forth driven by the muscles that do pronation and supination. The racket will swing back & forth. The muscles that do pronation are smaller muscles in the forearm.

Demo of Internal Shoulder Rotation. Take a racket in the hand as above, neutral wrist. Have your elbow straight. Now rotate the near straight arm from the shoulder. Try to not twist the forearm with any pronation. That is internal shoulder rotation and it is driven by the lat, pecs and some other shoulder muscles. The racket will swing back & forth and move like pronation. These ISR muscles are much larger than the forearm muscles that do pronation.

Now try to estimate the power of these two joint motions, pronation vs internal shoulder rotation. Safely rotate the wrist and racket with pronation & elbow bent at 90 degrees and then with internal shoulder rotation arm near straight, get some speed. I'm worried about asking you to get sound from the racket head and air. The muscles are shortening with active forces from Actin & Myosin.

The larger muscles of ISR will be capable of more power than the smaller forearm muscles of pronation.

For the serve, many of the sub-motions stretch the muscles that perform ISR. The muscles are like giant rubber bands ready to perform ISR very rapidly. I don't know what releases the pre-stretched muscles to start ISR. For ISR alone the near straight arm does not go anywhere, it stays in place, it just spins like a top. The bone that is driven is the humerus.

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What I am talking about is that last part of the stroke that occurs just before, during and just after contact. The hand travels maybe 8” but changes the string bed 180*. If I think about doing that from the shoulder, I don’t think I get much done.
I believe the power part of the serve is provided by the torso bringing the shoulder from low to high and then, once that is accomplished, smaller muscles provide the speed/snap for velocity and spin.
If I tried to teach someone to snap their fingers, I would talk about the thumb and middle finger opposing each other and then starting to offset the pressure until they slide off of each other. Telling them which muscle to contract in their forearm is unnecessary. ISR seems to much like the tail wagging the dog.

yossarian said:

...

He didn’t say he was confused about the joint motions. He just said that he feels his forearm rotates more during the serve, which is driven by rotation that first occurs at his shoulder

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That's pretty much the definition of being confused.

yossarian said:

I don’t know if this is technically true, but it is logically sound.

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"an argument is sound if it is both valid in form and its premises are true"

so no.

yossarian said:

Knowledge of the process has no tangible benefit to most tennis players

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This is just plain wrong

yossarian said:

, especially when you have found no way to cue it aside from “watch high speed video”

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I dare anyone to cue something verbally over teh interwebz to ten people they dont know and haven't talked to and get a consistent response.

"Never try to teach a pig to sing. It will only frustrate you and annoy the pig."
- Old Irish proverb

So I'll stop.
/k

#fwiw #goodluckwiththat

ballmachineguy said:

What I am talking about is that last part of the stroke that occurs just before, during and just after contact. The hand travels maybe 8” but changes the string bed 180*. If I think about doing that from the shoulder, I don’t think I get much done.
I believe the power part of the serve is provided by the torso bringing the shoulder from low to high and then, once that is accomplished, smaller muscles provide the speed/snap for velocity and spin.
If I tried to teach someone to snap their fingers, I would talk about the thumb and middle finger opposing each other and then starting to offset the pressure until they slide off of each other. Telling them which muscle to contract in their forearm is unnecessary. ISR seems to much like the tail wagging the dog.

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Get a clear high speed video and give the time range that the string bed changes 180 degrees "just before, during and after contact".

View the video and copy the address (the URL). Paste that in the post. Give the time of the serve to identify it, for example '37 sec'. If you need to count keystrokes to identify the exact frame 'serve at 37 sec plus period keystrokes from 12 to 20 after the video shows 36 sec change to 37 sec. The period key will advance a Youtube one frame. (it is possible that sometimes the video will advance more than one frame, an error, but not usually).

Serve compilation.
Use the period & comma keys to single frame.

Chas Tennis said:

View the video and copy the address (the URL). Paste that in the post. Give the time of the serve to identify it, for example '37 sec'. If you need to count keystrokes to identify the exact frame 'serve at 37 sec plus period keystrokes from 12 to 20 after the video shows 36 sec change to 37 sec. The period key will advance a Youtube one frame. (it is possible that sometimes the video will advance more than one frame, an error, but not usually).

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Before I go to the trouble, will it work better than my current method where I rapidly hit the play, pause icons super-fast with my thumb for slow mo?

ballmachineguy said:

Before I go to the trouble, will it work better than my current method where I rapidly hit the play, pause icons super-fast with my thumb for slow mo?

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What does it mean when you write "180" degrees?

For reference

To single frame on Vimeo, go full screen, hold down the SHIFT KEY & use the ARROW KEYS.

1) The racket shaft rotates (closes) roughly about 180 degrees.
( The head of the racket is fully in the frame for 15 frames. That time @240 fps, is 15 x 4.3 ms = 65 ms. I have to check frame rate. )

2) The racket face also rotates about 180 degrees. (For planes like the string plane, think of an arrow perpendicular to the plane of the strings. The so-called 'surface normal'.)

These rotations are in 3D and occur over about 65 milliseconds. The 65 ms depending mostly on the time of the follow through. The time leading to impact is not seen to vary very much for ATP players.

I rarely consider the time after impact in the follow through, because the server can use muscles to slow down the racket in a number of ways with different timing. 'Fully pronated" as shown, I believe, seems like a very useful position for learning, but some high level servers don't get to 'fully pronated', so its absence does not prove or disprove a high level serve.

But before impact, the last 30 milliseconds leading to first touch of the ball are much more consistent in their biomechanics. I believe that ISR, from start to impact, is about 25 milliseconds, more or less, for ATP flat and slice serves, angles 60-90? . Seeing the exact millisecond of the ISR start could be done but the video quality would have to be above average and 1000 fps.

Every position of the serve during its fastest parts has to be associated with a time down to milliseconds. ISR at its peak rotation rate has been estimated at 3000 degrees per second. That's 3 degrees per millisecond. At 240 fps an object that rotates at 3 d./ms rotates 13 degrees between frames.

Details like the above determine the quality of the high level serve.

Jeez, this thread sure went off on tangents. Has anyone seen the OP lately? Gotta wonder if he's gotten anything out of the past 50 or 60 posts in this runaway thread.

SystemicAnomaly said:

Jeez, this thread sure went off on tangents. Has anyone seen the OP lately? Gotta wonder if he's gotten anything out of the past 50 or 60 posts in this runaway thread.

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The OP started the thread in Sept 2019. Back then I said that the racket has to rise while impacting the ball. Posted a clear video showing the racket on the ball. Post #31.

OP posted again Nov 19, 2020 after a year. I presented the video-above-video showing the racket rising for comparisons. Then the thread got busy and no interest from the OP in his video.

Was the racket ever observed rising in one of the OP's videos?

Maybe we should not analyze videos that don't show what the OP's thread is asking for?