physics/science behind pronation

Chenx15

Banned
I would like to understand the physics behind pronation. i am not sure how it makes the ball stay up and makes it spin to go down. i am doing it on my serves but for the life of me i can't understand the physics behind it. unlike ground strokes the science is pretty much straigh forward. if someone can please show me the physics behind the pronation on a serve it will be greatly appreciated. thank you.
 
pronation does this:


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Only works with a BH grip or conti grip though because it moves the rackethead around the hand and accelerates it. just try at home.
 
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Chenx15

Banned
how does it make it spin up then down. when i am just observing is slowly and just rolling the ball on the racket i can't seem to understand it.

is there an illustration of the biomechanical movement of the forearm pronation with the racket and a tennis ball?
 

larry10s

Hall of Fame
what make the ball go up and spin down has to do with bernulli principle and magnus effect and gravity
pronation has to do with the anatomical movement of your forearm
as you approach contact.
if you serve with a continental grip or eastern bh grip you have to pronate some to hit the ball with the strings of the racquet
pronation also adds to racquet head speed which causes the ball to spin faster and allow the physics of ball spin to take over.
hope my abbreviated somewhat simplistic answer helped
 

toly

Hall of Fame
I would like to understand the physics behind pronation. i am not sure how it makes the ball stay up and makes it spin to go down. i am doing it on my serves but for the life of me i can't understand the physics behind it. unlike ground strokes the science is pretty much straigh forward. if someone can please show me the physics behind the pronation on a serve it will be greatly appreciated. thank you.
About physics behind pronation on a serve you can read thread http://tt.tennis-warehouse.com/showthread.php?t=361610
 

larry10s

Hall of Fame
how does it make it spin up then down. when i am just observing is slowly and just rolling the ball on the racket i can't seem to understand it.

is there an illustration of the biomechanical movement of the forearm pronation with the racket and a tennis ball?

brian gordon has a tremendous series of articles on the biomechanics of the serve which discusses this and more
www.tennisplayer.net
you will need to join for a month
when you log in you will see biomechanic on the left click on that and you will get to his articles
 
how does it make it spin up then down. when i am just observing is slowly and just rolling the ball on the racket i can't seem to understand it.

is there an illustration of the biomechanical movement of the forearm pronation with the racket and a tennis ball?

It's quite easy:

with a FH grip pronation moves the edge of the racket up this creating topspin on a WW forehand.

with a BH or conti grip on a serve it moves the face forward thus creating ball speed.
 

sureshs

Bionic Poster
I would like to understand the physics behind pronation. i am not sure how it makes the ball stay up and makes it spin to go down. i am doing it on my serves but for the life of me i can't understand the physics behind it. unlike ground strokes the science is pretty much straigh forward. if someone can please show me the physics behind the pronation on a serve it will be greatly appreciated. thank you.

If you try to hit a ball with a conti grip and swing the racquet on edge, what should theoretically happen? You would hammer the ball with the frame. The fact that you don't is because of pronation.
 

Chenx15

Banned
If you try to hit a ball with a conti grip and swing the racquet on edge, what should theoretically happen? You would hammer the ball with the frame. The fact that you don't is because of pronation.

I understand that, the ball should be moving sideways instead of up and down. because pronation is a horizontal brush instead of vertical
 

toly

Hall of Fame
I understand that, the ball should be moving sideways instead of up and down. because pronation is a horizontal brush instead of vertical
If you use continental grip and keep the wrist in neutral position during impact, pronation cannot produce brushing motion at all. But, wrist ulnar deviation can create topspin, sidespin etc.
 
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larry10s

Hall of Fame
I understand that, the ball should be moving sideways instead of up and down. because pronation is a horizontal brush instead of vertical

no
pronation is happening
while the arm is moving in an arc
the brush is not (rarely)horizontal or vertical its a blend of the 2
if you have heard the serving "tip"
hit up and out
thats whats happening
 

LeeD

Bionic Poster
Pronation has nothing to do with spin. It only adds rackethead speed, which you could spin or hit flat.
Hold racket close to an L. Now pronate. See how much muscleLESS effort adds to rackethead speed?
 

LeeD

Bionic Poster
OP is talking about serves only. He's already figured out how pronation helps in groundies.
Hold conti grip and try serving. You gotta pronate to flatten out your shots.
 
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sennoc

Guest
Pronation as a source of racquet's head speed at serves is NOT IMPORTANT. Dot.

Read some scientific papers, learn how to serve properly, do not write things which are straight way to injuries.
 

LeeD

Bionic Poster
Do any of you even hit a serve you can brag about?
Of course not, you don't pronate. Talking recent postings who say pronation doesn't add rackethead speed and those guys.
Does pronation need active muscles? NOPE!
 
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sennoc

Guest
LeeD, you have no idea about biomechanics of serves.

Pronation just rotates surface of racquet's head. You have to do that intentionally, this is a result of muscles' action. But this action doesn't mean that the velocity of racquet's head is significantly larger! Physically, pronation is not important source of energy. It adds NOTHING to kick serves and no more than 10% at flat serves.
 

LeeD

Bionic Poster
Yes, you of the 85 mph first serve telling someone not to pronate because it's of minor importance.
If pronation wasn't important to adding speed, everyone would serve with and eastern forehand grip.
 

sureshs

Bionic Poster
Yes, you of the 85 mph first serve telling someone not to pronate because it's of minor importance.
If pronation wasn't important to adding speed, everyone would serve with and eastern forehand grip.

Not arguing about the speed here (don't know), but eastern FH grip will make it difficult to hit slice, topspin, and top-slice serves.
 

sureshs

Bionic Poster
I understand that, the ball should be moving sideways instead of up and down. because pronation is a horizontal brush instead of vertical

It is a horizontal brush, followed by a downward and away motion. You can hit a slice serve without pronation, as some of the women do from the deuce court (righties)- they seem to come from the side on their arm, and supinate.
 

Manus Domini

Hall of Fame
If you use continental grip and keep the wrist in neutral position during impact, pronation cannot produce brushing motion at all. But, wrist ulnar deviation can create topspin, sidespin est.

aaaah no, that will hurt your wrist, trust me.

pronation will produce a nice brushing motion, you are clueless. If you don't play the sport, please don't just bring physics in because you are overthinking it...
 
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sennoc

Guest
Yes, you of the 85 mph first serve telling someone not to pronate because it's of minor importance.
If pronation wasn't important to adding speed, everyone would serve with and eastern forehand grip.

Man, you are an old rude ignorant without fundamental tennis knowledge. You are talking about things you do not understand. Your "advices" can be sources of really bad injuries.

First, you know nothing about my serves, so be nice and shut up.

Second, pronation in the sense presented here is the action of forearm. At serves, it is not important at all.

The sources of kinetic energy of racguet's head at serves are listed below:

1. Shoulder velocity generated by leg drive and trunk rotation.
2. Elbow velocity generated by upper arm, elevation and flexion.
3. Wrist speed generated by forearm extension, forearm pronation and upper arm internal rotation.
4. Hand flexion.

These sources sums to ca. 70% of kinetic energy of the racquet's head. The rest is "generated" by optimal transfer of energy along the kinetic chain.

Forearm pronation is an important part of the kinetic sequence, but it is not a source of energy, you uneducated master. It is fundamental if you want to optimally use other parts of kinetic chain as sources of energy. That's why it's so important. Without pronation of forearm you do not have access to the real sources of energy.

The main sources of energy at serves are: shoulders (10-15%), upper arm (55-65%!!!) and hand flexion (20-30%). Source: my 30+ years of tennis experience, my knowledge of physics as a physicist and "Biomechanics and tennis", B. Elliot, Br. J. Sports Med. 2006; 40; 392-396; doi:10.1136/bjsm.2005.023150. And many other scientific sources you have never read.

I have strong feeling, LeeD, that you have no idea about real tennis, your tennis skills are very low and this forum is a kind of substitution for you.
 
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sennoc

Guest
aaaah no, that will hurt your wrist, trust me.

pronation will produce a nice brushing motion, you are clueless. If you don't play the sport, please don't just bring physics in because you are overthinking it...

You are wrong, toly is right.
 

sureshs

Bionic Poster
Man, you are an old rude ignorant without fundamental tennis knowledge. You are talking about things you do not understand. Your "advices" can be sources of really bad injuries.

First, you know nothing about my serves, so be nice and shut up.

Second, pronation in the sense presented here is the action of forearm. At serves, it is not important at all.

The sources of kinetic energy of racguet's head at serves are listed below:

1. Shoulder velocity generated by leg drive and trunk rotation.
2. Elbow velocity generated by upper arm, elevation and flexion.
3. Wrist speed generated by forearm extension, forearm pronation and upper arm internal rotation.
4. Hand flexion.

These sources sums to ca. 70% of kinetic energy of the racquet's head. The rest is "generated" by optimal transfer of energy along the kinetic chain.

Forearm pronation is an important part of the kinetic sequence, but it is not a source energy, you uneducated master. It is fundamental if you want to optimally use other parts of kinetic chain as sources of energy. That's why it's so important. Without pronation of forearm you do not have access to the real sources of energy.

The main sources of energy at serves are: shoulders (10-15%), upper arm (55-65%!!!) and hand flexion (20-30%). Source: my 25 years of tennis experience, my knowledge of physics as a physicist and "Biomechanics and tennis", B. Elliot, Br. J. Sports Med. 2006; 40; 392-396; doi:10.1136/bjsm.2005.023150. And many other scientific sources you never read.

I have strong feeling, LeeD, that you have no idea about real tennis, your tennis skills are very low and this forum is a kind of substitution for you.

You are saying pronation unlocks sources of speed in the serve, LeeD is saying pronation is important for serve speed. Why is there a contradiction?
 
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sennoc

Guest
Both things are totally different.

If you think that pronation is a source of energy, you try to use muscles to reach the nonexisting goal. As a result, you can force your wrist (because you will experimentally discover that this action generates more energy when the racquet is not in line with your forearm).

If you know that pronation is NOT a source of energy, you just use your forearm to rotate racquet's head. You do that just before contact with the ball, when your arm is straight, so your wrist is safe.
 

LeeD

Bionic Poster
Sennoc, I have hammers from 16 oz to 26, you can borrow anytime to smash your head with... "muscle LESS effort" "active muscles, NOPE"....
So what you say is in line to propagate argument, because you didn't read what I wrote.
Try to understand the English language, then make yourself look silly on the internet.
 
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sennoc

Guest
Pronation has nothing to do with spin. It only adds rackethead speed

Oh. So you say I have problems with my English. Great, I know it's not my native language.

The real problem is that YOU have problems with - your English or your tennis knowledge.

In my opinion - your tennis knowledge is huge, but totally wrong in many important places. So hide your hammers, learn humility. The last thing we need here is an old 3.0 player as an Oracle.
 

LeeD

Bionic Poster
Pronation.... you can pronate onto a flat serve, or you can pronate onto a spin serve.
If you DON'T pronate, you will have NO rackethead speed.
So is pronation important? Think about it.
 
S

sennoc

Guest
You make serious mistakes and you are unable to say: "yes, I was wrong".

As I said: in my opinion you are an internet nerd with very flat tennis knowledge. Flat. With and without pronation.
 
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sennoc

Guest
Yes, number of posts decides about tennis "knowledge".

In your case.
 

Manus Domini

Hall of Fame
You are wrong, toly is right.

when I used ulnar deviation, my wrist started killing me. I base it off personal expericence, so unless I am doing something wrong with ulnar deviation and have a less-than-normal strength wrist, I stand by my experiences
 

salsainglesa

Semi-Pro
check out this video, its about rotation

internal rotation and pronation are analog movements. In this position rotation does help acceleration alongside a pronation followthrough, but, chech out that the position, it has to be this one... in this position the flexion of the hand actually doesnt help produce speed, it only changes the raquet head angle. If the arm is fully extended as in the amateur player example then it does accelerate the raquet, but this force wont be nearly as strong as a rotated shoulder and pronated followthrough.

http://www.youtube.com/watch?v=lTRvxaBMh8s
 

bhupaes

Professional
Sennoc, when you say the upper arm contributes, you mean upper arm rotation as in internal shoulder rotation, right? This would move the racquet in the same way (almost) as forearm pronation, and because of this, a lot of people probably consider upper arm rotation to also be pronation. I agree, pure forearm pronation is a positioning/directing mechanism.
 

LeeD

Bionic Poster
"Offline" is what allows pronation to ADD to the rackethead speed. So you pronate to ADD to rackethead speed, as I said.
 
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sennoc

Guest
Sennoc, when you say the upper arm contributes, you mean upper arm rotation as in internal shoulder rotation, right? This would move the racquet in the same way (almost) as forearm pronation, and because of this, a lot of people probably consider upper arm rotation to also be pronation.

I agree.

The problem is that both kind of rotations work at different parts of kinetic chain. Internal shoulder rotation is a source of energy at serves when there is L between upper arm and forearm. Pronation (of forearm) as a source of energy works when we have L between forearm and racquet. As a result, there are totally different forces acting at elbow/wrist. If you think that pronation of forearm is a source of energy, you will force your wrist to do impossible things. This is not a source of energy, this is source of injuries.

LeeD, find another thread.
 

LeeD

Bionic Poster
You are a techno weenie on the techniques of hitting a serve.
A good server pronates, period. If he's not allowed to pronate, his serves are slow, period.
Pronation good, not pronating BAD!
How can you debate whether a server holds the racket off line? Of course they do, every server who can serve! You MUST know that, or shut the frick up!
 
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sennoc

Guest
I fpound this one... wich explains better the position.
http://www.youtube.com/watch?v=1t6bLABbebc&NR=1

This is a good advice if you want to hit serves at full speed. But the explanation is wrong.

Racquet not in line with forearm has nothing to do with additional energy. It is a kind of buffer - wrist is not fully extended, its position is more natural at impact, more stable and the risk of injuries is lower.

Watch best servers, frame by frame. They pronate as late as possible, just before contact. Why? Because pronation is not important. They have to pronate because they do not want to hit the ball by the edge of the racquet. They do that as soon as possible, because they want to use as long as possible the main source of energy at serves: arm rotation.

So, why to pronate? Can't we start with the racquet's head in hitting position? Try to do that (carefully!).

We can't. Our wrists are too weak to deal with so huge forces. This is the real source of forearm pronation at serves: weakness of wrists.

LeeD, could you help me, just once? Could you tell me, where can I find "Ignore" button here?
 
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salsainglesa

Semi-Pro
Sennoc no disrispect here, but if serve was only done by the hand then that would be true, but there are more axis and levers than that.
you know the drill, legs, hips, torso, shoulder elbow, bones of the forearm... this kinetic chan not only produces the necesary power but also the necesary alignment.

The most effective spin serve is done accelerating the raquet through the edge, the alignment can be done with the torso... the raquet moves through the edge in reference to the body, but the torso is moving and aligns the string bed in reference to the ball... its two separate things... pronation depending on hand position and grip can add spin or pace.
 

LeeD

Bionic Poster
I get it now.
You see things from a different perspective, but the same thing!
You see the glass as half full. Other's see it as half empty.
You say we are weaklings and pronate to achieve rackethead speed. We say we pronate to get rackethead speed thru pronation, but don't dwell on our weakness.
We both agree we cannot swing fast with an open face, so a closed face is necessary to get up to speed, then the opening to contact the ball square for a flat serve. That supports my argument that we should swing faster on spin second serves than we do for flat first serves because WE CAN!
So we are different (our theories), but the same (in actual practice)!
 

Fugazi

Professional
Yes, you of the 85 mph first serve telling someone not to pronate because it's of minor importance.
If pronation wasn't important to adding speed, everyone would serve with and eastern forehand grip.
You got that right. Sampras had tremendous pronation...
 

spacediver

Hall of Fame
I'm composing a post that will explain the relationship between pronation and racquet head speed. Give me a bit of time. Am including custom rendered graphics of the biomechanics.
 
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sennoc

Guest
Sennoc no disrispect here, but if serve was only done by the hand then that would be true, but there are more axis and levers than that.

There is more, I agree. Much more, in reality. But this is a scientific fact: iternal rotation of upper arm generates 40% of energy, horizontal flexion 15-25% depending on the type of serve. Contribution of palm ulnar flexion is ca. 30% at power serves and negligible at kick serves, while ulnar flexion generates ca. 20% at kick serves and almost nothing at power serves.

People believe in the magical role of other parts of kinetic chain because they usually watch the best servers. They (best pros) really use many many other elements, so many that they sum to important values. But what about players like Wawrinka? His kinetic chain is very short but he serves quite well. Does he use magical powers of the other universes?

You also have to remember that kinetic energy of racquet's head is not a simple sum of energies generated at every part of kinetic chain. This energies contribute to ca. 70% of kinetic energy of the stroke. Just 70%. The rest - ca. 30% of the sum!!! - is generated by energy transfer along kinetic chain. I have a beautiful picture here from one of the scientific papers, but I can't attach the file and I'm too lazy to find a host. But I promise I'll post it here - in hours after LeeD's first video from the court ;)

And here is the most funny part. If you want to have an access to this "additional" 30%, you have to use your kinetic chain in a way similar to a whip. The problem with amateur tennis players is that they do not use this method. But if you start working on proper serve technique, you unintentionally learn how to use better energy transfer! So, when a player starts to think about "upper arm rotation", about "pronation", he begins to move energy along kinetic chain! "Wow!" - he thinks - "that pronation is a really huge source of energy!".

Funny, don't you think?

Toly, give me please some time.
 
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