Nadal's 130 plus MPH serve

[uspta146749877]

Brian basically answered my question about how grip can impact internal shoulder rotation when comparing a continental to a forehand grip. However, most sources that I read or heard indicate that Nadal moved his grip from an eastern backhand TOWARDS an eastern forehand. They did not state that he moved TO an eastern forehand grip. I think this is a significant distinction. Brian states much the same thing when he says "less to the backhand than in the past".

One thing that I did not see addressed in Brian's post was how the grip affects the angle of impact with the ball. Given the same toss location it seems that an eastern backhand will have a slightly different angle of impact than a continental which can produce more spin and less speed. If you look at some of Nadal's older first serves in the stroke archive you will see that his toss is pretty far to his right compared to other left handed players. His racquet face is also not as parallel to the net (at impact) as many top players.

Based on the picture that Phil posted, it seems that he moved his toss to the left and adjusted his grip away from the eastern backhand.

If John gets a chance to film Nadal in the future, it would be an interesting analysis to see exactly how his serve has changed.

Please see "Biomechanical Principles of Tennis Technique" by Duane
Knudson ( if you can find it,say,in a library)

[gzhpcu]

Another good book is "The Physics and Technology of Tennis" Brody, Cross and Lindsey. Lots of math on collisions.

[uspta146749877]

How do we measure a speed of ball?

Come on, Julian. You must have read Gordon's series on the serve at least as many times as I have. On top of that, you have the most recent stuff he and Yandell did with the motion capture analysis on Sampras's serve that showed he got 40 of 90 MPH of racket head speed in the last couple of hundreths of a second, from a combination of internal rotation and pronation that we normally refer to as pronation although it's just as much or more internal rotation, and it works better with the more truely continental grip than a somewhat more Eastern forehand grip. Instead of talking about semantics and what where came from, what do you yourself with your physicists analytical mind think about the primary question: where is Nadal getting the additional speed while maintaining his high percentages? I think Christoffe (if that is who gave that answer) has a pretty good explanation. Don't give me a link. Tell us what you think!

don

Don,
a book by Knudson has couple important points:

1.a speed of a ball measured ( say by a speed gun) is a down-the court component of a speed of a ball ONLY.


2.a component of a speed of a ball parallel to a shaft of a racket is NOT
measured at all by a speed gun.

3.a trajectory of a ball is NO more than 10 degrees below the horizontal.

Now let me add couple comments of mine:
1.please note a very detailed/important distinction between a speed of
a racket and a down-the court component of a speed of a ball-it is kind of obvious but ...

2.please see my post #60 above as well.

3.if future films of Nadal's serve expected it would be good to know
which parts of a serve/angles/trajectories should be analyzed.

4.let us denote by
M a mass of a racket
m is a mass of a ball
v is a speed of a racket at impact or just before an impact
vspeed is a down-the court component of speed of a ball just after impact
vspin is a component of a speed of a ball parallel to a shaft of a racket just after impact
We can produce an approximate equation

1/2*M v*v=0.75 * m *( 1/2 *vspeed * vspeed + 1/2*vspin * vspin)

0.75 is just an ad hoc fudge number.We may discuss it later.

Therefore
mvspeed can be estimated from the equation above
We see that larger mvspin slows down a ball MOREl
which is an expected result.

julian

julian mielniczuk uspta certified pro juliantennis@comcast.net
www.julianmielniczuk.usptapro.com Courtside Tennis Club,Bedford,MA

[uspta146749877]

Cross

Another good book is "The Physics and Technology of Tennis" Brody, Cross and Lindsey. Lots of math on collisions.

Does this book have anything pertinent/related about a current conversation
about a Nadal's serve?

[gzhpcu]

Does this book have anything pertinent/related about a current conversation
about a Nadal's serve?

Not in respect to grips.

[uspta146749877]

Asking for favour

Not in respect to grips.

Could you,please,looked into a book by Plagenhoef?
Does he talks about a relation between grips and a speed of a racket?
I do NOT have a copy of a book.
Thank you.
Maybe we have another book by the same author:
"Patterns of Human Motion"

[uspta146749877]

Please let me know

The following is the link for the picture to which I refer in my above post. The link goes to a slide show, and I am referring to the third picture of Nadal where he is facing the camera.

http://www.tennisplayer.nethttps://www.tennisplayer.net/article/tour-portraits-serving-arms/

If the link does not work it is in the Serving Arms link in the Tour Portraits section of this web site.

What is serving grip of Kuznetsova
in

http://www.tennisplayer.nethttps://www.tennisplayer.net/article/tour-portraits-serving-arms/

[blake_b]

Thanks Julian and Phil for the book recommendations, and to Julian for the additional explanation. I have an M.S. degree in Biomechanics, but I have not done any work related to tennis, and I do not currently work in the Biomechanics field. It sounds like these books will give me some good background in the biomechanics of tennis.

I have enjoyed this discussion.

Kutnetsova's grip looks like a continental to me, but it does not look as far towards the backhand as Nadal's grip in older pictures.

[uspta146749877]

Bear with me

Thanks Julian and Phil for the book recommendations, and to Julian for the additional explanation. I have an M.S. degree in Biomechanics, but I have not done any work related to tennis, and I do not currently work in the Biomechanics field. It sounds like these books will give me some good background in the biomechanics of tennis.

I have enjoyed this discussion.

Kutnetsova's grip looks like a continental to me, but it does not look as far towards the backhand as Nadal's grip in older pictures.

I am trying to simplify a presentation-bear with me for couple of hours,please

[gzhpcu]

Could you,please,looked into a book by Plagenhoef?
Does he talks about a relation between grips and a speed of a racket?
I do NOT have a copy of a book.
Thank you.
Maybe we have another book by the same author:
"Patterns of Human Motion"

This is what Plagenhoef says concerning grip firmness on page 87:

The final important factor in obtaining control and ball speed is the firmness of the grip at contact. A vigorous body motion, in attempting to reach high racket speeds, may very well result in less hand control, which will result in loss of ball speed and accuracy.

He then has a graph showing the relationship between the ball speed, racket head velocity, and the striking mass (dependent on grip firmness).

He concludes that racket head speed developed is no more important than the firmness of the grip. He says a high racket speed makes it difficult to hold the racket firmly. He cites an example where Gonzalez hit one serve 2 mile per hour faster than another serve with a swing 11 mph slower.

Interesting comments, but I wonder if he took the spin factor into consideration. Maybe the slower serve by Gonzalez had a bit more spin...

On page 6, under "Service Grips" he says:

Many instructors start out teaching the Eastern forehand grip for serving, but I start with the Continental. The Continental grip will allow full hand action and allow the butt end to clear the wrist as the hand flexes. It also places the racket face at a desirable angle for swinging across the ball for spin. An advanced player often shifts to an Eastern backhand with the thumb around when hitting an extreme spin serve, as this grip facilitates hitting across the ball while still keeping the racket face pointing in the proper direction.

[uspta146749877]

For Phil

Maybe you have another book by the same author:
"Patterns of Human Motion"

[uspta990770809]

Firmness of the Grip

This is what Plagenhoef says concerning grip firmness on page 87:


He then has a graph showing the relationship between the ball speed, racket head velocity, and the striking mass (dependent on grip firmness).

He concludes that racket head speed developed is no more important than the firmness of the grip. He says a high racket speed makes it difficult to hold the racket firmly. He cites an example where Gonzalez hit one serve 2 mile per hour faster than another serve with a swing 11 mph slower.

Interesting comments, but I wonder if he took the spin factor into consideration. Maybe the slower serve by Gonzalez had a bit more spin...

On page 6, under "Service Grips" he says:

I have a bit of a problem with this point about firmness of the grip. It's very important to have absolute control of the racket head, but that doesn't mean you have to squeeze it tight. I put a lot of emphasis on getting the student to keep the racket snug in their hand, not necessarily tight. It is the weight and the momentum of the racket head that hits the ball. The weight and power of the body is used to generate power and speed in the racket head. If I can get the racket head moving in the right direction at the moment of impact (there is a vector that describes the momentum of the racket head in a physics analysis), I want to release that power at the moment of impact into the ball. If I hold on tight my necessarily circular motion will pull the racket off the path of the ball sooner than if I "release" at impact. I don't know if Plagenhof was actually measuring grip pressure or just assuming it. I expect it was probably the latter.

The analogy I like to draw for my students is the surgeon with a scalpel. I expect new surgeons hold the scalpel much tighter than an experienced, confident surgeon who lets the sharp edge of his scalpel do the work for him while he controls where it goes. Imagine trying to play a brisk piece on a piano or just type fast at your keyboard with tense wrists and forearms. Even if you can do it, you will be cramping up in no time.

don

[uspta146749877]

For Don

A fax did NOT make it-please check a number or a fax machine

[uspta146749877]

Plagenhoef

Phil,
my understanding is that the following laws do NOT hold
during a collision/contact of a racket with a ball:

1.a momentum of a racket is NOT preserved
i.e a momentum of a ball is NOT equal a momentum of a racket
2.a linear momentum is NOT preserved

3.a angular momentum is NOT preserved

4.an kinetic energy is NOT preserved
i.e a kinetic energy of a ball is NOT equal a kinetic energy of a racket



Please let me know whether Plagenhoef makes any comments on this subject

[gzhpcu]

I have a bit of a problem with this point about firmness of the grip. It's very important to have absolute control of the racket head, but that doesn't mean you have to squeeze it tight. I put a lot of emphasis on getting the student to keep the racket snug in their hand, not necessarily tight. It is the weight and the momentum of the racket head that hits the ball. The weight and power of the body is used to generate power and speed in the racket head. If I can get the racket head moving in the right direction at the moment of impact (there is a vector that describes the momentum of the racket head in a physics analysis), I want to release that power at the moment of impact into the ball. If I hold on tight my necessarily circular motion will pull the racket off the path of the ball sooner than if I "release" at impact. I don't know if Plagenhof was actually measuring grip pressure or just assuming it. I expect it was probably the latter.

The analogy I like to draw for my students is the surgeon with a scalpel. I expect new surgeons hold the scalpel much tighter than an experienced, confident surgeon who lets the sharp edge of his scalpel do the work for him while he controls where it goes. Imagine trying to play a brisk piece on a piano or just type fast at your keyboard with tense wrists and forearms. Even if you can do it, you will be cramping up in no time.

don

I assume he means a firm grip at impact and not during the service movement, which would be very negative.