how much does rate of pronation matter ?

I've recently learned pronation in serving and it's a wonderful feeling! My serves just got more powerful and controlled at the same time!

I do wonder if it matters how fast the pronation is done. I've come across some video that say that the twisting of the forearm in adds angular momentum to the racket for extra power, and I believe it (having a background in Physics). But I'm just not sure how much additional power it can add, percentage-wise. I think I've experienced some of it, when I got lucky a couple of and my service motion just clicked.

At this point I'm already happy with just pronating gradually. Hitting the ball in a pronated arm gives a feeling of solid and controllable impact and has already added noticeable mph (and kick, for kick serves) to my serves. Any extra coming from a fast pronation will be welcome for sure!
 

ballmachineguy

Hall of Fame
Well, you should be bringing the racquet head to the ball leading with the edge of the frame. It really does feel like it happens in an instant. You don’t want to have it happen just as the racquet start up to the ball. The racquet head edge should rotate as much as it is going to in 18” or so.
Make sure there is a noticeable angle between the forearm and the racquet shaft. If the shaft is in line with the forearm, there will be less of an effect velocity and probably spin wise too due to “pronation.”
“Calling all cars, calling all cars!” Someone is out there calling ISR pronation again. Be on the lookout.
 

socallefty

G.O.A.T.
Highly recommend bookmarking these links which are 3 papers that are widely referenced on the biomechanics of serves.

The 8 stage model is a good paper for evaluating the serve by Mark Kovacs and Todd Ellenbecker.
Contributions of Upper Limb Segment Rotations During the Power Serve in Tennis by Elliot et al.
Long Axis Rotation: The missing link in proximal-to-distal segmental sequencing by Marshall and Elliot.

The second paper by Dr. Elliott is in particular pure gold in terms of understanding what is going on with the biomechanics of the different parts of the body during the serve. As I interpret it, the twisting to make the strings hit the ball instead of the edge of the frame is forearm pronation and he shows timing and extent of forearm pronation in both his papers. Here is detail from Dr.Elliott - “Forearm pronation therefore plays a dual role in developing racket speed prior to impact while also positioning the racket head for impact”.

So, I think he is saying that forearm pronation is required to position the racquet properly for impact - from seeing the pics, I think the edge would hit the ball without this positioning using forearm pronation. There is a second stage of forearm pronation that happens after contact also during the finish as illustrated in Dr. Kovacs article which helps some players finish with the racquet away from the body with strings facing out - but, that is different from the pronation (with timing graphs shown) before contact in Dr. Elliott’s paper.

However, the papers show that internal shoulder rotation (ISR) and wrist flexion generate most of the racquet head speed and power at contact especially if accompanied by shoulder abduction at the optimal 100+/-10 degree angle. (Detail from Dr Kovacs paper - ”The mean shoulder abduction just before contact is approximately 100° which is similar to the 100° ± 10° angle to produce maximal ball velocity and minimal shoulder joint loading in baseball pitching. This suggests an optimum contact point of 110° ± 15° for the tennis serve. At ball contact, ball velocity is determined by shoulder internal rotation and wrist flexion. Elbow flexion (20° ± 4°), wrist extension (15° ± 8°), and front knee flexion (24° ± 14°) are minimal at contact. Trunk is tilted 48° ± 7° above horizontal in Olympic professional tennis players”.)

Coaches are validated in using the term pronation to explain to students how to hit the ball with the strings after coming on edge with a continental grip as opposed to a pancake serve. Chas and others are correct in stating that to generate high pace, focus on having the proper sequence to maximize shoulder ISR - but, wrist flexion is key too at contact to generate power along with shoulder abduction at the optimal angle). Those who say there is no pronation at all are clearly contradicting Dr. Elliott who might be the most biomechanics researcher on tennis.

I highly recommend the scientifically inclined to read the three papers as there are clear explanations for each segment of the tennis serve. I agree that coaches and players can teach and learn by being shown the proper motion in sequence and don’t have to understand all these terms. However, understanding them at least will prevent us from throwing the wrong terms around or giving wrong information. I think there has been a lot of wrong information posted on this forum by posters incorrectly understanding ISR partly due to the position taken by some that only ISR is happening for the entire forward motion of the racquet - there is a lot more going on than that while ISR contributes to more than half of the racquet head velocity at contact.
 

Chas Tennis

G.O.A.T.
I've recently learned pronation in serving and it's a wonderful feeling! My serves just got more powerful and controlled at the same time!

I do wonder if it matters how fast the pronation is done. I've come across some video that say that the twisting of the forearm in adds angular momentum to the racket for extra power, and I believe it (having a background in Physics). But I'm just not sure how much additional power it can add, percentage-wise. I think I've experienced some of it, when I got lucky a couple of and my service motion just clicked.

At this point I'm already happy with just pronating gradually. Hitting the ball in a pronated arm gives a feeling of solid and controllable impact and has already added noticeable mph (and kick, for kick serves) to my serves. Any extra coming from a fast pronation will be welcome for sure!
Well, you should be bringing the racquet head to the ball leading with the edge of the frame. It really does feel like it happens in an instant. You don’t want to have it happen just as the racquet start up to the ball. The racquet head edge should rotate as much as it is going to in 18” or so.
Make sure there is a noticeable angle between the forearm and the racquet shaft. If the shaft is in line with the forearm, there will be less of an effect velocity and probably spin wise too due to “pronation.”
“Calling all cars, calling all cars!” Someone is out there calling ISR pronation again. Be on the lookout.
Learn to view serve videos in high speed video. Learn to see Internal Shoulder Rotation, it is driven by large muscles.

Forum search: Internal Shoulder Rotation
Forum Member: Chas Tennis

Amazingly ISR was missed by tennis researchers until 1995!

The Tennis Serve Nuthouse

Google: Internal Shoulder Rotation tennis serve
 

10sbeast888

Hall of Fame
Learn to view serve videos in high speed video. Learn to see Internal Shoulder Rotation, it is driven by large muscles.

Forum search: Internal Shoulder Rotation
Forum Member: Chas Tennis

Amazingly ISR was missed by tennis researchers until 1995!

The Tennis Serve Nuthouse

Google: Internal Shoulder Rotation tennis serve

not necessarily a miss. there must be ways to teach the serve without even mentioning the ISR.

coaches need to understand what causes the snap.

this channel does a great job of emphasizing the right to left moving bending the elbow and then leading with the elbow. that's essentially what's needed to generate the snap.

once the player experiences the snap, ISR just happens naturally, without knowing what ISR or SE is.
 

Chas Tennis

G.O.A.T.
not necessarily a miss. there must be ways to teach the serve without even mentioning the ISR.

coaches need to understand what causes the snap.

this channel does a great job of emphasizing the right to left moving bending the elbow and then leading with the elbow. that's essentially what's needed to generate the snap.

once the player experiences the snap, ISR just happens naturally, without knowing what ISR or SE is.
I go with video evidence and not words.

I don't know where the "wrist snap" is in ATP serve videos.

Raonic serve.
To single frame on Vimeo, stop video, GO FULL SCREEN, hold down the SHIFT key and use the ARROW keys.

Raonic serve (same match).

For these Raonic serve videos, can you point out the time and location of the racket path where the "wrist snap" occurs.

For example, time 3 sec plus 12 forward arrow keys from the frame when "3" first appeared - to specify exact frame.

For ISR, I use the shadows at the elbow as an indicator of ISR. Of course ISR also turns every thing below the elbow, including the forearm and the wrist. To see elbow shadows move requires a fast shutter speed to reduce motion blur, otherwise shadows can be lost in the motion blur.
 
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10sbeast888

Hall of Fame
I go with video evidence and not words.

I don't know where the "wrist snap" is in ATP serve videos.

Raonic serve.
To single frame on Vimeo, stop video, Go FULL SCREEN, hold down the SHIFT key and use the ARROW keys.

Raonic serve (same match).

For these Raonic serve videos, can you point out the time and location of the racket path where the "wrist snap" occurs.

For example, time 3 sec plus 12 forward arrow keys from the frame when "3" first appeared - to specify exact frame.

it's not a single frame. say the 2nd video around 00:06 at the 'big L' when the racket is about horizontal... that's when the snap has mostly been released.

since you are the in-house biomechanic aficionado - to me understanding the snap is the key as every shot needs to be built from the hand down to the ground, in the exact opposite sequence of the k chain.

I can explain it based on my own understanding and experience, but have not dug deep into any research.

the snap is nothing like any other SSC.. it's unique only to the serve.


again this channel - why does he teach a folded elbow, then lead with the elbow.

supination and straight arm are mutually limiting.. i.e. if you bend the elbow you can supinate more.

hence the first move is a right-to left elbow bend into the trophy.

then as you lead with the elbow. the supination deepens, and the bend deepens as well - simply due to inertia.

now as you fire the k-chain (certainly the spine engine being part of it). the arm is gonna gather speed and it wants to straighten due to centrifugal.

this is where the mutual limit comes in.... the supination is already super-loaded with the bend, now the arm wants to straighten, which puts makes it even more super-loaded and the load snaps out.

it's a unique feature due to the radial ulnar structure. different from any other kind of SSC.

I believe this is a key area for coaching in order to teach the serve.. the goal is to over-load the forearm/elbow area... and the spine engine discussion can be part of the loading process.
 

Chas Tennis

G.O.A.T.
it's not a single frame. say the 2nd video around 00:06 at the 'big L' when the racket is about horizontal... that's when the snap has mostly been released.

since you are the in-house biomechanic aficionado - to me understanding the snap is the key as every shot needs to be built from the hand down to the ground, in the exact opposite sequence of the k chain.

I can explain it based on my own understanding and experience, but have not dug deep into any research.

the snap is nothing like any other SSC.. it's unique only to the serve.


again this channel - why does he teach a folded elbow, then lead with the elbow.

supination and straight arm are mutually limiting.. i.e. if you bend the elbow you can supinate more.

hence the first move is a right-to left elbow bend into the trophy.

then as you lead with the elbow. the supination deepens, and the bend deepens as well - simply due to inertia.

now as you fire the k-chain (certainly the spine engine being part of it). the arm is gonna gather speed and it wants to straighten due to centrifugal.

this is where the mutual limit comes in.... the supination is already super-loaded with the bend, now the arm wants to straighten, which puts makes it even more super-loaded and the load snaps out.

it's a unique feature due to the radial ulnar structure. different from any other kind of SSC.

I believe this is a key area for coaching in order to teach the serve.. the goal is to over-load the forearm/elbow area... and the spine engine discussion can be part of the loading process.
You are not sure what the "wrist snap" looks like in a high speed video?

I'm not sure either and can not point "wrist snap" out in a video.

I don't remember the term 'wrist snap' being used in a serve biomechanics publication. ?
 

SystemicAnomaly

Bionic Poster
I've recently learned pronation in serving and it's a wonderful feeling! My serves just got more powerful and controlled at the same time!

I do wonder if it matters how fast the pronation is done. I've come across some video that say that the twisting of the forearm in adds angular momentum to the racket for extra power, and I believe it (having a background in Physics). But I'm just not sure how much additional power it can add, percentage-wise. I think I've experienced some of it, when I got lucky a couple of and my service motion just clicked.

At this point I'm already happy with just pronating gradually. Hitting the ball in a pronated arm gives a feeling of solid and controllable impact and has already added noticeable mph (and kick, for kick serves) to my serves. Any extra coming from a fast pronation will be welcome for sure!
Note that the "pronation" that you refer to is really a shoulder rotation (ISR) assisted by forearm pronation. The ISR normally plays a somewhat larger role in RHS (racket head speed) and the rotation of the hand / racket face. Despite this, coaches usually refer to this arm rotation (ISR + forearm pronation) simply as "pronation".

Note that this arm rotation happens after the Big L position (see image below). The racket head is still "on edge" at the Big L. The rotation commences during the last 1/3 (to 1/2) of the upward swing to contact. So the rotation is fairly rapid. The rotation continues after contact.

The Big L position:
 
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SystemicAnomaly

Bionic Poster
not necessarily a miss. there must be ways to teach the serve without even mentioning the ISR.

coaches need to understand what causes the snap.

this channel does a great job of emphasizing the right to left moving bending the elbow and then leading with the elbow. that's essentially what's needed to generate the snap.

once the player experiences the snap, ISR just happens naturally, without knowing what ISR or SE is.
@Chas Tennis

Agree that a proper serve & OH smash can be successfully taught without ever mentioning ISR (or ESR).

Even tho, it is an incomplete (partial) explanation of the rotation of the hand (& racket face), "pronation" of the forearm will often yield the desired result. But even using the term, pronation, is not absolutely necessary for teaching a proper serve / smash.

I first came across the concept of forearm pronation more than 40 years ago (early '80s) wrt to forehand strokes in badminton -- particularly overhead badminton strokes. (This concept had been introduced in a college thesis, from the 1960s, by Dr James Poole, an an elite badminton player). I first heard pronation applied to tennis instruction of the serve & smash later in the 1980s.

Even tho I had successfully incorporated forearm pronation (along with ISR) in my strokes in the '80s, my stroke mechanics were still flawed due to suboptimal racket drop mechanics. This stemmed from the misleading "scratch the back" instruction that was prevalent in tennis (and badminton) coaching in the '70s, '80s and beyond.

It wasn't until the '90s that I learned to use ESR to load the shoulder for a proper racket drop. However, I was not aware of the terminology, ESR and ISR, until much later. Despite my ignorance of these terms, back in the 90s, I am certain that I was properly using both ESR and ISR for my tennis serve & OH smash at that time.

I have mixed feelings about using the term, "snap" for tennis serve instruction. It might be acceptable as long as the desired action is properly demonstrated & reinforced. But I absolutely abhor the phrase, "wrist snap", either for tennis or badminton strokes.

The so-called "snap" is primarily arm rotations (ISR+ pronation) along with moderate wrist action (articulations). Some ppl might also consider elbow extension (& flexion) as part of the "snapping" action.
 

10sbeast888

Hall of Fame
@Chas Tennis

Agree that a proper serve & OH smash can be successfully taught without ever mentioning ISR (or ESR).

Even tho, it is an incomplete (partial) explanation of the rotation of the hand (& racket face), "pronation" of the forearm will often yield the desired result. But even using the term, pronation, is not absolutely necessary for teaching a proper serve / smash.

I first came across the concept of forearm pronation more than 40 years ago (early '80s) wrt to forehand strokes in badminton -- particularly overhead badminton strokes. (This concept had been introduced in a college thesis, from the 1960s, by Dr James Poole, an an elite badminton player). I first heard pronation applied to tennis instruction of the serve & smash later in the 1980s.

Even tho I had successfully incorporated forearm pronation (along with ISR) in my strokes in the '80s, my stroke mechanics were still flawed due to suboptimal racket drop mechanics. This stemmed from the misleading "scratch the back" instruction that was prevalent in tennis (and badminton) coaching in the '70s, '80s and beyond.

It wasn't until the '90s that I learned to use ESR to load the shoulder for a proper racket drop. However, I was not aware of the terminology, ESR and ISR, until much later. Despite my ignorance of these terms, back in the 90s, I am certain that I was properly using both ESR and ISR for my tennis serve & OH smash at that time.

I have mixed feelings about using the term, "snap" for tennis serve instruction. It might be acceptable as long as the desired action is properly demonstrated & reinforced. But I absolutely abhor the phrase, "wrist snap", either for tennis or badminton strokes.

The so-called "snap" is primarily arm rotations (ISR+ pronation) along with moderate wrist action (articulations). Some ppl might also consider elbow extension (& flexion) as part of the "snapping" action.

elbow flex then extend is actually a big part of it.

imagine hitting a fh with a w grip and bent elbow... you have ISR and pronation. there is a release, but no snap.

I laid out my understanding the role of the elbow in making the serve so snappy compared to other shots.
 

Chas Tennis

G.O.A.T.
@Chas Tennis

Agree that a proper serve & OH smash can be successfully taught without ever mentioning ISR (or ESR).

Even tho, it is an incomplete (partial) explanation of the rotation of the hand (& racket face), "pronation" of the forearm will often yield the desired result. But even using the term, pronation, is not absolutely necessary for teaching a proper serve / smash.

I first came across the concept of forearm pronation more than 40 years ago (early '80s) wrt to forehand strokes in badminton -- particularly overhead badminton strokes. (This concept had been introduced in a college thesis, from the 1960s, by Dr James Poole, an an elite badminton player). I first heard pronation applied to tennis instruction of the serve & smash later in the 1980s.

Even tho I had successfully incorporated forearm pronation (along with ISR) in my strokes in the '80s, my stroke mechanics were still flawed due to suboptimal racket drop mechanics. This stemmed from the misleading "scratch the back" instruction that was prevalent in tennis (and badminton) coaching in the '70s, '80s and beyond.

It wasn't until the '90s that I learned to use ESR to load the shoulder for a proper racket drop. However, I was not aware of the terminology, ESR and ISR, until much later. Despite my ignorance of these terms, back in the 90s, I am certain that I was properly using both ESR and ISR for my tennis serve & OH smash at that time.

I have mixed feelings about using the term, "snap" for tennis serve instruction. It might be acceptable as long as the desired action is properly demonstrated & reinforced. But I absolutely abhor the phrase, "wrist snap", either for tennis or badminton strokes.

The so-called "snap" is primarily arm rotations (ISR+ pronation) along with moderate wrist action (articulations). Some ppl might also consider elbow extension (& flexion) as part of the "snapping" action.
Thanks for your detailed history, it is the most complete experience that I've seen, covering so many years.

What if in the 1970's, the terms and biomechanics had been explained to you and some top tennis players and top coaches explained them - as they could do now? And safety issues were well known and explained to all, and individual limitations were better known scientifically. That is what I wanted in the 1970's, so in a way, I want to post to myself now what I wanted to know when I was much younger.......as a model for my writing. Would you like me to also post to a younger you, back in the 1970's?

Isn't that simply posting what is true?
 

Chas Tennis

G.O.A.T.
In a college catalog, Amherst stated why it was necessary to write an essay as part of the college application process.

'It is only as we attempt to write, do we realize the quality of our thoughts.'
 

Chas Tennis

G.O.A.T.
I've recently learned pronation in serving and it's a wonderful feeling! My serves just got more powerful and controlled at the same time!

I do wonder if it matters how fast the pronation is done. I've come across some video that say that the twisting of the forearm in adds angular momentum to the racket for extra power, and I believe it (having a background in Physics). But I'm just not sure how much additional power it can add, percentage-wise. I think I've experienced some of it, when I got lucky a couple of and my service motion just clicked.

At this point I'm already happy with just pronating gradually. Hitting the ball in a pronated arm gives a feeling of solid and controllable impact and has already added noticeable mph (and kick, for kick serves) to my serves. Any extra coming from a fast pronation will be welcome for sure!

A short 2006 publication by Bruce Elliott, one of the earliest tennis researchers for the 1995 publication on Internal Shoulder Rotation and the serve. See references.

PMC publications are free online in the NCBI collection.

Early Internal Shoulder Rotation measurements might have some measurement difficulties, but ISR is required to achieve the high racket head speed for impact.
 
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