Forehand Topspin Drive

[Cheetah]

..................

[TheCheese]

Originally Posted by rkelley

Rotating his forearm about the axis along his forearm (aka pronation or supination) by its very definition, would require any body perpendicular to that axis, namely his racquet in the picture, to change orientation. If Fed pronates his forearm in the picture, the racquet's tip (the axis from the handle to the tip) will go from pointing to the side to pointing at the camera and slightly down. I may not be communicating my meaning well, but it's not something you can disagree with.

I agree that this motion would not change the angle that the racquet makes with the forearm. Flexing or extending his wrist, or radial or ulnar deviation would do that, but not pronation or supination.

Since his arm is almost straight rotating his upper arm at the shoulder about the axis along his upper arm (aka ISR), would have a similar effect on the racquet's orientation as pronation/supination.

Whatever you want to call it, I personally try to get my racquet and arm in the position that Fed has in the picture.

I think you might be having a hard time getting a feel for where his racket is in relation to his forearm from this camera angle. Check out the side view.

Pronation isn't going to make his racket tip point at the camera. All it's doing is closing his racketface towards the ground.

[julian]

Originally Posted by Cheetah

http://www.youtube.com/watch?v=soADAL_uGs8&t=22s
http://www.youtube.com/watch?v=ESFU2IR_Dj0
http://www.youtube.com/watch?v=Fp_XHBXGbUs&t=31s
http://www.youtube.com/watch?v=APTKk580TkM&t=36s

Hi,
could you explain thoughts behind these links?
Thank you

[5263]

Originally Posted by TheCheese

How much you brush across the ball diagonally determines the amount of topspin you generate.

How flat/vertical your stroke path is effects the trajectory of your shot.

To hit a flat topspin drive you brush diagonally across the ball with a flatter stroke path.

OP, above seems to be a pretty good post. Did it help you along with the other comments along these lines?

[Geology_Rocks!]

Originally Posted by TheCheese

Exactly. I don't see it.

We're defining the direction of the tip as the same direction a vector pointing along the handle would be pointed, I'm assuming. Pronation would only rotate the racket around that axis, it wouldn't change its direction at all.

If Fed wasn't pronating, a vector pointing upwards perpendicular to the plane of the back of his hand would be pointing backwards, rather than skywards.

No. Pronation would not rotate the racket around the handle axis, Not without ulnar deviation, and there is no ulnar deviation there, his wrist is neutral.

The closed racket face is caused by ISR. Please, from the ready position holding the racket with a eastern grip lift your right elbow to your side. The racket will stay parallel to the ground with a closed face, correct?

http://www.youtube.com/watch?v=DkUSTi4U7Io

Watch Monfils, he really exaggerates this movement, watch how his elbow goes up.

[Geology_Rocks!]

Originally Posted by Cheetah

... despite the fact that I posted videos clearly showing the pronation occuring?

If you hold a racket in front of you with your right hand and pronate what happens?

Do you disagree on what I said about the Delpo Novak comparison?

[dominikk1985]

pronation only closes the racket face if your forearm and racket are in line.

however since you grip that racket in an angle and on top of that lay the wrist back the pronation will swing the racket around the long axis of the forearm creating upward movement.

if you use a conti grip pronation can even contribute to the forward acceleration of the racket.

[julian]

Originally Posted by toly

Definition – Forearm pronation is counterclockwise forearm rotation.

1.Does it apply to a lefthander?
2.Does it apply literally for all three strokes:forehand,backhand and serve?

[julian]

Originally Posted by toly

Definition – Forearm pronation is counterclockwise forearm rotation.

Is the definition below an acceptable one?
---->
Supination
From Wikipedia, the free encyclopedia
Jump to: navigation, search

Supination is a position of either the forearm or foot. When the arms are unbent and at the sides, the forearm is in supination when the palm faces to the front (anteriorly), or faces up. Supination in the foot occurs when a person appears "bow-legged" with their weight supported primarily on the lateral side of their feet (5th Metatarsal).[citation needed]

The hand is supine in the anatomical position (i.e., palms facing up during autopsy). This action is performed by the Biceps brachii and the Supinator muscle.

Supination is the opposite of pronation.

[toly]

Originally Posted by julian

1.Does it apply to a lefthander?
2.Does it apply literally for all three strokes:forehand,backhand and serve?

1. No.
2. Yes.

[julian]

Originally Posted by toly

1. No.
2. Yes.

Post #129 is more interesting

[toly]

Originally Posted by julian

Is the definition below an acceptable one?
---->
Supination
From Wikipedia, the free encyclopedia
Jump to: navigation, search

Supination is a position of either the forearm or foot. When the arms are unbent and at the sides, the forearm is in supination when the palm faces to the front (anteriorly), or faces up. Supination in the foot occurs when a person appears "bow-legged" with their weight supported primarily on the lateral side of their feet (5th Metatarsal).[citation needed]

The hand is supine in the anatomical position (i.e., palms facing up during autopsy). This action is performed by the Biceps brachii and the Supinator muscle.

Supination is the opposite of pronation.

I don’t like Wikipedia definition. There are too many useless words and I believe Supination is not position, but motion.

[julian]

Originally Posted by toly

I don’t like Wikipedia definition. There are too many useless words and I believe Supination is not position, but motion.

Could you provide the definition of ELBOW SUPINATION ?
I believe the term is used in blog#7 of www.log.tennisspeed.com

So your definition would be:
The ELBOW SUPINATION is the motion which ....
Please feel dots

Questions:
1.Does Sharapova have ELBOW SUPINATION? (for forehand) or does she supinate?

2.Does Federer have ELBOW SUPINATION? (for forehand)

3.Does Del Potro have ELBOW SUPINATION (for forehand)

If #1,#2 and #3 answered correctly I will send you a chocolate bar by E-mail
Possible answers:
a) yes
b) no
c) maybe
d) Julian,you are such a pain
e)other to be specified

[rkelley]

Originally Posted by TheCheese

I think you might be having a hard time getting a feel for where his racket is in relation to his forearm from this camera angle. Check out the side view.

Pronation isn't going to make his racket tip point at the camera. All it's doing is closing his racketface towards the ground.

Check out the pictures that toly posted about forearm and wrist movements. This is my understanding of the definitions.

In the picture of Fed that you posted the racquet is making very roughly a 90° angle with the forearm, true? That means that the racquet, more specifically the line from the handle to the tip, is in a plane that is normal to the forearm axis. Let's define the positive direction of the forearm axis from the hand to the elbow. Let's define the positive direction of the racquet axis as from the handle to the tip. Pronation would therefore be a positive rotation (right hand rule) of the racquet axis about the forearm axis.

Because racquet axis and the forearm axis are normal, neither pronation or supination will cause a rotation about racquet axis, which would be required to open or close the racquet face.

In the picture you provided a human should be able to pronate their forearm about 90° from the position shown. The racquet would be point more toward the camera, though in this case not at the camera. In your picture Fed's racquet is not quite in the same position as in the other Fed picture. His upper arm as rotated so that the racquet is pointing a bit more backwards.

Please remember that I am making some approximations on some of these positions. His racquet and forearm are not exactly normal (90°), but they are certainly not in-line. His forearm isn't pointed straight down but rather at an angle to the ground, so the plane normal to the axis of the forearm is not parallel to the ground.

Sorry for all of the engineering/math speak, but I don't know how else to unambiguously communicate my meaning.

[julian]

Originally Posted by rkelley

Check out the pictures that toly posted about forearm and wrist movements. This is my understanding of the definitions.

In the picture of Fed that you posted the racquet is making very roughly a 90° angle with the forearm, true? That means that the racquet, more specifically the line from the handle to the tip, is in a plane that is normal to the forearm axis. Let's define the positive direction of the forearm axis from the hand to the elbow. Let's define the positive direction of the racquet axis as from the handle to the tip. Pronation would therefore be a positive rotation (right hand rule) of the racquet axis about the forearm axis.

Because racquet axis and the forearm axis are normal, neither pronation or supination will cause a rotation about racquet axis, which would be required to open or close the racquet face.

In the picture you provided a human should be able to pronate their forearm about 90° from the position shown. The racquet would be point more toward the camera, though in this case not at the camera. In your picture Fed's racquet is not quite in the same position as in the other Fed picture. His upper arm as rotated so that the racquet is pointing a bit more backwards.

Please remember that I am making some approximations on some of these positions. His racquet and forearm are not exactly normal (90°), but they are certainly not in-line. His forearm isn't pointed straight down but rather at an angle to the ground, so the plane normal to the axis of the forearm is not parallel to the ground.

Sorry for all of the engineering/math speak, but I don't know how else to unambiguously communicate my meaning.

Do you know answers to questions in post #133?
I have one chocolate bar left

[julian]

Originally Posted by rkelley

Check out the pictures that toly posted about forearm and wrist movements. This is my understanding of the definitions.

In the picture of Fed that you posted the racquet is making very roughly a 90° angle with the forearm, true? That means that the racquet, more specifically the line from the handle to the tip, is in a plane that is normal to the forearm axis. Let's define the positive direction of the forearm axis from the hand to the elbow. Let's define the positive direction of the racquet axis as from the handle to the tip. Pronation would therefore be a positive rotation (right hand rule) of the racquet axis about the forearm axis.

Because racquet axis and the forearm axis are normal, neither pronation or supination will cause a rotation about racquet axis, which would be required to open or close the racquet face.

In the picture you provided a human should be able to pronate their forearm about 90° from the position shown. The racquet would be point more toward the camera, though in this case not at the camera. In your picture Fed's racquet is not quite in the same position as in the other Fed picture. His upper arm as rotated so that the racquet is pointing a bit more backwards.

Please remember that I am making some approximations on some of these positions. His racquet and forearm are not exactly normal (90°), but they are certainly not in-line. His forearm isn't pointed straight down but rather at an angle to the ground, so the plane normal to the axis of the forearm is not parallel to the ground.

Sorry for all of the engineering/math speak, but I don't know how else to unambiguously communicate my meaning.

If we go couple frames forward to you think:
a) a racket will be more closed
b) a racket will be more open
c) a racket will stay the same
d)Federer will shank a ball
A bottle of champagne available for you-one left

[5263]

Maybe out of my league here, since I rarely use terms like this since most
students have NO IDEA in this area of terms, but...

aren't we really talking more ISR instead of pronation?

[toly]

Originally Posted by julian

Could you provide the definition of ELBOW SUPINATION ?
I believe the term is used in blog#7 of www.log.tennisspeed.com

So your definition would be:
The ELBOW SUPINATION is the motion which ....
Please feel dots

IMO, Elbow Supination is forearm supination.

Forearm Supination is forearm clockwise rotation about forearm longitude axis.

[julian]

Originally Posted by toly

IMO, Elbow Supination is forearm supination.

Forearm Supination is forearm clockwise rotation about forearm longitude axis.

You did NOT answer questions #1,#2 and #3
Terrible,just terrible
Do you think serve is supinated or pronated or both?
A can of caviar left

[Geology_Rocks!]

rkelley, I think we are seeing the same thing (thank you!)

5263, yes, there is no pronation during the takeback.