Hitting Up on Serves

[Topspin Shot]

Tomaz posted a great article on feeltennis about how good servers hit up on serves while not popping the ball up. The gist is that tossing the ball forward into the court automatically lowers the trajectory of your serve. So hit up as much as possible but toss far enough in front that your serves go into the box rather than the fence. Here's the link. http://www.feeltennis.net/swing-up-serve/

 

[GregSV]

Tomaz is unique in his blending of theory and practice, really an oustanding teacher. I haven't seen the new video fully, but understand that the tilting of your body is the key (which occurs after tossing the ball far enough into the court). So it might feel as if your hitting the ball upward, because you're tilted you're actually hitting it downward into the service box.

 

[Chas Tennis]

Could someone show in a high speed video the part of the serve that is intended when saying "Hitting Up on Serves", point out the exact time that 'up' applies to. I've seen the advice to 'hit up on the ball' often and similar comments in research publications. Of course, if you are going to impact the ball at a high point, the racket head obviously has to go up.

Raonic serve.

I could as well say "hit forward on serves" and that is more what I see at impact in high speed videos, at least for some milliseconds around impact. In high speed videos, at impact for the slice and flat serve the strings aren't going up very much. On the kick serve, the strings have considerable upward motion, more than for the slice or flat serves.

Is this more a feeling of the server?

Or what appears to be happening as the server's head moves forward?

 

[GregSV]

Read the article and watch the video at http://www.feeltennis.net/swing-up-serve/
It's all explained very clearly. Here's a hint (taken from Tomaz' site):

 

[Flatballs]

Could someone show in a high speed video the part of the serve that is intended when saying "Hitting Up on Serves", point out the exact time that 'up' applies to. I've seen the advice to 'hit up on the ball' often and similar comments in research publications. Of course, if you are going to impact the ball at a high point, the racket head obviously has to go up.

Raonic serve.

I could as well say "hit forward on serves" and that is more what I see at impact in high speed videos, at least for some milliseconds around impact. In high speed videos, at impact for the slice and flat serve the strings aren't going up very much. On the kick serve, the strings have considerable upward motion, more than for the slice or flat serves.

Is this more a feeling of the server?

Or what appears to be happening as the server's head moves forward?

What do you mean? What are you trying to say?

I don't see the benefit in paralyzing and confusing this concept with over-analysis of biomechanical technicalities. It achieves nothing.

If you actually read the article its pretty clear and concise what Tomaz is postulating.

Quote: "So even though Milos’ hand is “open”, the racquet face is actually pointing slightly down of course, it’s just that he is not directing the ball down by “closing” the hand down on the ball but actually leaning into the court and aligning the racquet face slightly down with his body!......So, if he wasn’t leaning into the court and he tossed the ball right above his head – and if he didn’t change his swing – then his serve would literally fly up!"

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[sureshs]

"So even though Milos’ hand is “open”, the racquet face is actually pointing slightly down"

No, the photo shows that the perpendicular to the strings is pointing slightly up at the beginning of contact. That is clear if you mask the entire body with your palm and just look at the racket in post #4. The fallacy of his logic with the other (tilted) photo is that he has not tilted the horizontal and vertical lines! That is not how it works. In Physics, the entire coordinate system must be tilted for the laws to become valid again.

"The reason why the ball then goes down is because HE IS TILTED."

No, the ball goes down due to two reasons: 1. gravity and 2. At the end of the dwell time, the racket may have crossed the apex and the perpendicular to the strings in the deformation zone may be pointing ever so slightly downward. It is even more subtle because the plane of the deformation zone need not be parallel to the plane of the strings but slightly skewed.

Tomaz is making it appear like the case of a person swinging his arms upwards while he is hanging upside down - so he is actually swinging downwards. I don't see that happening here.

"If they tossed the ball inside the court and at the same time pointed the racquet downwards, they would hit every ball in the net."

No, the fallacy here is thinking that the ball path is straight. It is possible to point the racket slightly downwards and yet clear the net, because the path is a parabola with the bulge around the net region.

Tomaz has at least made a good attempt to understand the complex nature of this problem, instead of just parroting what coaches and posters here have been saying all these years, and that is a good start. but he is still not correct.

 

[Chas Tennis]

The the article relies heavily on how things feel as seen by Tomaz.

About Raonic around ball impact, he says -
"That is how (h)is arm “feels” at contact. It feels like he is serving up."

Is that information on feeling from Raonic? Tomaz has the view that the angle of the wrist gives the server the feeling of 'up'. I don't know anything about that. Does anyone have some supporting information?

For myself, I find that when I speculate about what others feel on tennis strokes what I come up with is usually all based on my own subjective thinking and feelings. It's difficult to know with any objective evidence if two players feel the same about a tennis stroke.

Rotation from ISR. During ball contact with the strings the racket head is rapidly rotating around the axis of the upper arm. At impact, this axis of the arm is tipped forward and slightly to the right as can be seen by the arm orientation in serve videos . This rotation rate may reach around 3000°/sec. If the racket head did not slow down from impact, at 3000°/sec, in 4 milliseconds of contact the racket face would rotate 12°.

Rotation from Swing. The second rotation is the swing that is closing the racket face. There are more than one rotation and each has a center. The wrist joint, shoulder joint and body all contribute to this rotation that closes the racket face. The rotation about the wrist is the biggest swing contributor to racket head speed. The rotation rate might be 1000-2000°/sec?? And that might close the racket face up to several degrees of rotation in the 4 milliseconds of ball string contact.

A video camera with a frame rate of a few hundred frames per second captures a frame at a random time during ball-string contact - not the initial ball string contact. It is not possible to say - based on one frame - when that frame was captured during the 4 milliseconds of ball-string contact. You cannot say if the racket was open or closed for initial contact. Since the player's serves are not reproducible, they miss 30%-40% of first serves, you would have to study a number serves to get stats to know how closed the racket face is for typical successful serves.

The way the ball and strings interact is very complex and requires very high speed video to capture several frames during the milliseconds of ball-string contact. 2000 fps or so.

Video showing both the horizontal rotation from ISR (upper arm is the axis) and the racket face closing rotation mostly from the wrist joint motion. When I measure the closing angle I only get about 1°during ball-string contact, much less than I estimated. ? I don't understand that.

Measuring the racket closing rotation from the first frame that the racket edge appears to the first contact with the ball, shows that the racket rotated about 4-5°before contact. The edge of the head apparently did not rotate during ball-string contact because the impact slowed the racket head or the racket head was distorted. ?

 

[Gazelle]

Somehow I'm inclined to believe Tomaz instead of Sureshs.

 

[sureshs]

Somehow I'm inclined to believe Tomaz instead of Sureshs.

Me too

He has a clever idea. If a rod is moving up in an arc in one place, and then does the same motion when extended forward, up can become down. That is the crux of his argument. Unfortunately, the photo that he says is at contact seems to have the racket pointing up even when Raonic is extended. Perhaps he is right but chose the wrong example.

http://tt.tennis-warehouse.com/inde...f-supposed-142-mph-serve.536904/#post-9428596

It is interesting that he claims that the extending forward effectively causes hitting down on the ball. This is different from the usual claim that the ball is actually hit up but gravity causes a slightly downward trajectory. IMO, the second is closer to reality, with the caveat that if the ball was actually hit up with Raonic's swing speed, it would shoot up, not down. Gravity is much weaker than electromagnetic forces which make up the mechanical contact force. A small magnet can overcome earth's gravity and pull up a nail. The deformation during the dwell period is the key. It may cause the ball to be flung slightly downward. Even more subtly, the overall string plane may be slightly open, but the local deformation area caused by the falling ball may be slightly closed.

 

[psv255]

Thanks for the link. Some key concepts in there. Aside from this main point of the article it's good that Tomaz emphasized the elbow as a key pivot around which the racket moves through the ball - IMO really important to building a technically correct serve.

 

[GuyClinch]

I liked the article too. My takeaway though is that serves are hit with the hand moving rapidly upward - because that's the best way to accelerate the racquet. And that a forward lean can compensate for a slightly open racquet face at contact (relative to the arm).. That squares with the idea that on a serve with less forward lean (like a kick serve) your racquet is going to be more closed..

http://twu.tennis-warehouse.com/learning_center/kickserve.php

You can absolutely hit up with a closed face - this is what happens on every single pro forehand..

Could someone show in a high speed video the part of the serve that is intended when saying "Hitting Up on Serves", point out the exact time that 'up' applies to. I've seen the advice to 'hit up on the ball' often and similar comments in research publications. Of course, if you are going to impact the ball at a high point, the racket head obviously has to go up.

Its not obvious at all. You could in fact hold the racquet out high and then swing down at the ball. A good example of this kind of shot would be a spike volley.. Yes true the racquet head did have to go up - but it need not be swung up. There is a difference.

 

[Chas Tennis]

Thanks for the link. Some key concepts in there. Aside from this main point of the article it's good that Tomaz emphasized the elbow as a key pivot around which the racket moves through the ball - IMO really important to building a technically correct serve.

What is meant by "elbow". In most high level serves the elbow joint is not moving at impact, it's extended.

 

[Topspin Shot]

"So even though Milos’ hand is “open”, the racquet face is actually pointing slightly down"

No, the photo shows that the perpendicular to the strings is pointing slightly up at the beginning of contact. That is clear if you mask the entire body with your palm and just look at the racket in post #4. The fallacy of his logic with the other (tilted) photo is that he has not tilted the horizontal and vertical lines! That is not how it works. In Physics, the entire coordinate system must be tilted for the laws to become valid again.

"The reason why the ball then goes down is because HE IS TILTED."

No, the ball goes down due to two reasons: 1. gravity and 2. At the end of the dwell time, the racket may have crossed the apex and the perpendicular to the strings in the deformation zone may be pointing ever so slightly downward. It is even more subtle because the plane of the deformation zone need not be parallel to the plane of the strings but slightly skewed.

Tomaz is making it appear like the case of a person swinging his arms upwards while he is hanging upside down - so he is actually swinging downwards. I don't see that happening here.

"If they tossed the ball inside the court and at the same time pointed the racquet downwards, they would hit every ball in the net."

No, the fallacy here is thinking that the ball path is straight. It is possible to point the racket slightly downwards and yet clear the net, because the path is a parabola with the bulge around the net region.

Tomaz has at least made a good attempt to understand the complex nature of this problem, instead of just parroting what coaches and posters here have been saying all these years, and that is a good start. but he is still not correct.

You're technically correct about the coordinate system, but Tomaz's main point still stands. If Milos were to keep his swing the same but toss directly over the baseline, he would hit the serve into the fence. Tossing forward is the difference that allows him to hit the serve in the box.

 

[psv255]

What is meant by "elbow". In most high level serves the elbow joint is not moving at impact, it's extended.

Sorry, to clarify, the actual, final pivot would be the forearm as the racket comes around into the ball at an angle to it - I mentioned the elbow as it is the place where the forearm starts.

 

[user92626]

1) Is the serve like the overhead?

2) Do you hit up with the overhead?

 

[sureshs]

You're technically correct about the coordinate system, but Tomaz's main point still stands. If Milos were to keep his swing the same but toss directly over the baseline, he would hit the serve into the fence. Tossing forward is the difference that allows him to hit the serve in the box.

Tossing forward also reduces the length of the court so you cannot say that it is 100% related to this issue only. But I get your point. I think Tomaz has something going here but his picture did not show it.

 

[Rubens]

Tried it today. It works. My motion is more relaxed now. It's still slow, though..

 

[Chas Tennis]

FYI

http://www.spalla.it/handout/2012_aprile/ELLIOTT_Biom_of_serve_Italy_20_m.pdf

Take a look at #21, in particular, the yellow diagram used to illustrate the slide. Notice anything about the diagram?

Video frames can show more clearly what is going on. A few words don't describe and can be misleading, 'hit up and out'.

Toly composite picture.

In this internal shoulder rotation serve, the hand and, to a lesser degree, the racket goes 'up and out' relative to the ball's trajectory . But the 'out' part is mostly because the hand path is going 'out'. Relative to the hand path, the racket is actually coming in because of the rotation of ISR as the picture shows. Does 'hit up and out' describe this complex 3D motion in an unambiguous way?

How does the real serve compare to the serve illustration in the presentation, #21?

(For a Waiter's Tray technique there is little or no arm rotation so the hand path can be more directly at the ball.)

 

[RajS]

Tomaz posted a great article on feeltennis about how good servers hit up on serves while not popping the ball up. The gist is that tossing the ball forward into the court automatically lowers the trajectory of your serve. So hit up as much as possible but toss far enough in front that your serves go into the box rather than the fence. Here's the link. http://www.feeltennis.net/swing-up-serve/

I have found that tossing the ball higher and raising the contact point would make the ball go in more consistently. If I toss low, I tend to hit it long. I had therefore come to the conclusion that the ISR or snap effectively changes the direction of the racket head but it has to travel upwards some for that, and the sensation is one of hitting upwards. But what you are saying also make sense. Since my serve is working well now, I won't change anything though!

 

[sureshs]

FYI

http://www.spalla.it/handout/2012_aprile/ELLIOTT_Biom_of_serve_Italy_20_m.pdf

Take a look at #21, in particular, the yellow diagram used to illustrate the slide. Notice anything about the diagram?

Video frames can show more clearly what is going on. A few words don't describe and can be misleading, 'hit up and out'.

Toly composite picture.

In this internal shoulder rotation serve, the hand and, to a lesser degree, the racket goes 'up and out' relative to the ball's trajectory . But the 'out' part is mostly because the hand path is going 'out'. Relative to the hand path, the racket is actually coming in because of the rotation of ISR as the picture shows. Does 'hit up and out' describe this complex 3D motion in an unambiguous way?

It doesn't, and you correctly point out the reason when you use the phrase "coming in." Up and out will only send the ball up and out of the court.

 

[sureshs]

1) Is the serve like the overhead?

2) Do you hit up with the overhead?

But what if the overhead was hit from the baseline? Think about it.

 

[shindemac]

This is a mightily confusing concept for something that should be so simple. There are also 2 concepts being discussed in this thread so don't confuse the 2. Just because it has the word 'UP', it doesn't mean it refers to the same thing.

I don't like to say 'hit up on the ball' because frankly, it isn't necessary. Beginners with pancake motions will pop it into the sky. Why are we asking them to hit up on the ball? Intermediate servers will figure this out for themselves, lest their serve will always go into the net. Do you know what happens when your serves always go into the net? You will adjust and automatically aim higher. Nobody needs to tell you anything, because the net is telling you. Maybe a light bulb will go off in your head, and you finally understand what the axiom means and why it is important. If you don't understand any of this, then you are not at the level to apply this yet so don't worry.

IOW, there is nothing to see or understand here. Trying to apply things that pros do for rank beginners w pancake motions isn't good. A lot of advices get parroted wo understanding why we do them. Sure, any good player needs to hit up on the ball. So that means a total beginner must hit up on the ball to be good, right? Well, hopefully yall can figure out the answer by now...

 

[5263]

swing up, to hit out, and the ball goes down. illustrates how important the 4 inches of contact are instead of thinking of 4ms of contact Imo.

 

[Raul_SJ]

I could as well say "hit forward on serves" and that is more what I see at impact in high speed videos, at least for some milliseconds around impact. In high speed videos, at impact for the slice and flat serve the strings aren't going up very much. On the kick serve, the strings have considerable upward motion, more than for the slice or flat serves.

I think Tomaz is saying that if you toss into the court, you can observe the swing path and the points where the racket is open, vertical, and begins to close. If you make contact near the window where the racket is vertical, the swing path will naturally bring the ball down -- no need to adjust the hand and racket angle. But if you don't toss into the court, it will lead to errors with adjusting the hand. (I believe this applies to both flat and kick serves).

Tomaz:
"If you hit the ball in the correct contact point, then the ball will go down. The major mistake you may have been making is trying to direct the ball down by changing the racquet angle with your hand."
"
OTOH, FYB says it is acceptable to not toss into the court (toss lands on the baseline).
Frank Salazar does not look to be tossing into the court as Raonic does, but according to Tomaz, this should lead to hand adjustment errors.

Frank Salazar Flat Serve Above Fuzzy Yellow Balls

Tomaz: Difference in ball trajectory depending on your contact point

 

[Chas Tennis]

I think Tomaz is saying that if you toss into the court, you can observe the swing path and the points where the racket is open, vertical, and begins to close. If you make contact near the window where the racket is vertical, the swing path will naturally bring the ball down -- no need to adjust the hand and racket angle. But if you don't toss into the court, it will lead to errors with adjusting the hand. (I believe this applies to both flat and kick serves).

Tomaz:
"If you hit the ball in the correct contact point, then the ball will go down. The major mistake you may have been making is trying to direct the ball down by changing the racquet angle with your hand."
"
OTOH, FYB says it is acceptable to not toss into the court (toss lands on the baseline).
Frank Salazar does not look to be tossing into the court as Raonic does, but according to Tomaz, this should lead to hand adjustment errors.

Frank Salazar Flat Serve Above Fuzzy Yellow Balls

Tomaz: Difference in ball trajectory depending on your contact point

There is considerable variety on how far into the court the high level players impact the ball and how far their front foot lands in. Raonic is at the top end.

Salazar's serve is struck a foot or more into the court. That is not very far into the court. We have these great overhead view of the serve from FYB videos and Toly composites and Salazar's technique look very good to me, but I don't have stats on the typical high level distances into the court for impact and the front foot landing distance. How typical are his serves regarding where impact is?

For the last picture of Tomaz - I was hitting my overheads down too sharply, they would bounce back up too high and become slow set ups or go into the net. I asked my instructor what was going on. He described exactly what is shown in the picture. If the ball is too far forward, the racket will be closed at impact and vice versa if too close. He demonstrated it to me by holding a ball up in front of me. He would move closer and farther back and have me put my racket on the ball. He pointed out to me how open or closed the racket had to be based on how far I was from the falling ball. My hitting sharply down overheads immediately went from ~40% to less than 10% of my overheads. It was all crystal clear. He showed me that in 2 or 3 minutes. This is a great demonstration!

Later, I learned from videos that high level overheads, like the serve, involve internal shoulder rotation. That ISR overhead technique develops pace with two rotations of the racket, swing plus ISR. If your develop overhead pace with only a Waiter's Tray type swing, as I believe that most rec players do, all pace is developed by making the racket close very rapidly. That is harder to time because the racket is closing so fast and as a result the overhead will be less consistent in the high or low direction. Or, the racket can be slowed down to make the timing easier, as is commonly done. Does this make sense to anyone?

Another way to say it would be to 'position yourself the proper distance from the falling ball'.

 

[sureshs]

Tomaz: Difference in ball trajectory depending on your contact point

The angle between the racket and the hand is totally different in the two pics, so what is Tomaz trying to say? I think he is saying that a rod rotating about a pivot in a vertical plane moves upwards for the first half and downwards for the second half. Got that. What else? If the axis is more inclined forward into the court, the downward part occurs sooner.

 

[ARKustom93]

Me too

He has a clever idea. If a rod is moving up in an arc in one place, and then does the same motion when extended forward, up can become down. That is the crux of his argument. Unfortunately, the photo that he says is at contact seems to have the racket pointing up even when Raonic is extended. Perhaps he is right but chose the wrong example.

http://tt.tennis-warehouse.com/inde...f-supposed-142-mph-serve.536904/#post-9428596

It is interesting that he claims that the extending forward effectively causes hitting down on the ball. This is different from the usual claim that the ball is actually hit up but gravity causes a slightly downward trajectory. IMO, the second is closer to reality, with the caveat that if the ball was actually hit up with Raonic's swing speed, it would shoot up, not down. Gravity is much weaker than electromagnetic forces which make up the mechanical contact force. A small magnet can overcome earth's gravity and pull up a nail. The deformation during the dwell period is the key. It may cause the ball to be flung slightly downward. Even more subtly, the overall string plane may be slightly open, but the local deformation area caused by the falling ball may be slightly closed.

On that: At max impact load, given that the ball is hit off-center(about 3"up toward the tip), you get 'asymmetrical string deflection', meaning the short portion toward the tip will angle a couple of degrees more than the 'long end'. Even without bringing the other factors at play into the picture, that sharper angle on it's own is already sufficient in creating 'down force', altering the launch angle. Not rocket science, either; as a simple way of testing this, all you need is a rubber band and a projectile(piece of paper, folded into a 'V'). Fashion a make-shift slingshot by tensioning the band between two fingers, and pick a target. You probably already know what's gonna happen if you don't properly center the projectile on the rubber band before pulling the shot ...

 

[sureshs]

On that: At max impact load, given that the ball is hit off-center(about 3"up toward the tip), you get 'asymmetrical string deflection', meaning the short portion toward the tip will angle a couple of degrees more than the 'long end'. Even without bringing the other factors at play into the picture, that sharper angle on it's own is already sufficient in creating 'down force', altering the launch angle. Not rocket science, either; as a simple way of testing this, all you need is a rubber band and a projectile(piece of paper, folded into a 'V'). Fashion a make-shift slingshot by tensioning the band between two fingers, and pick a target. You probably already know what's gonna happen if you don't properly center the projectile on the rubber band before pulling the shot ...

It goes downward?

Your post brings out an important point that the racket head may appear to be vertical or even a little bit open, but the asymmetrical string deflection actually exerts a downward force. This explains the conundrum frequently cited on this forum: If the ball is not being hit down, why is it angled slightly down (on traditional first serves)? Gravity alone cannot explain it. I have been discussing this for years on this forum and it is nice to see good analysis come up. In the past, only personal insults would result.

What happens is over a period of time, pros (and rec players too) have found out how to exploit this, albeit sub-consciously. They "know" where to contact the ball and at what speed so that they can be hitting at vertical or even upwards, but bringing their racket tip quickly over the apex during the dwell time to give the asymmetric string deflection effect. When they go wrong, they put the ball into the net or long. If they are too careful, the serve is too slow. This is the real reason why pros have ridiculously low first serve percentages (compared to say table tennis or badminton). As 5263 said, much is happening at contact than meets the naked eye.

 

[shindemac]

"If they tossed the ball inside the court and at the same time pointed the racquet downwards, they would hit every ball in the net."

No, the fallacy here is thinking that the ball path is straight. It is possible to point the racket slightly downwards and yet clear the net, because the path is a parabola with the bulge around the net region.

No, this is the main crux of the argument (hit up on your serve). All good servers must point their racket up to avoid hitting the net. To be clear, 'pointing the racket up' means the racket face is 'open', not that the racket face is pointing at the sky.

Look at any pro serve at the point of contact. Their racket face will never be closed or neutral. Always open.

 

[shindemac]

The the article relies heavily on how things feel as seen by Tomaz.

About Raonic around ball impact, he says -
"That is how (h)is arm “feels” at contact. It feels like he is serving up."

Is that information on feeling from Raonic? Tomaz has the view that the angle of the wrist gives the server the feeling of 'up'. I don't know anything about that. Does anyone have some supporting information?

Yes. Tomaz doesn't need to understand what Raonic is feeling. Any good server needs to do the same thing. Any good server will tell you that it feels like 'they are serving up'. Even with my serve half as good as Raonic, I can tell you that it 'feels like I'm serving up.'

Your line of questioning is weird. Did you ever think better players might know something you don't?

 

[shindemac]

If you make contact near the window where the racket is vertical, the swing path will naturally bring the ball down -- no need to adjust the hand and racket angle.

Tomaz:
"If you hit the ball in the correct contact point, then the ball will go down. The major mistake you may have been making is trying to direct the ball down by changing the racquet angle with your hand."
"

No, he isn't saying that. At the correct contact point, you still need to adjust your hand and racket angle.

Remember, the expression isn't 'Don't hit down on your serve." It's 'Hit up on your serve."

If you are a good server, this advice applies. Beginners need not worry. Good servers don't need to be told this.

 

[Chas Tennis]

No, this is the main crux of the argument (hit up on your serve). All good servers must point their racket up to avoid hitting the net. To be clear, 'pointing the racket up' means the racket face is 'open', not that the racket face is pointing at the sky.

Look at any pro serve at the point of contact. Their racket face will never be closed or neutral. Always open.

I believe that knowing how closed the racket face is at the initial contact is a very close call and that you would have difficulty making a reasonable case by "Look at any pro serve at the point of contact." The requirements for just knowing the point of contact are quite a trick. How would you do that, what equipment, etc.?

 

[sureshs]

Look at any pro serve at the point of contact. Their racket face will never be closed or neutral. Always open.

I wouldn't call 3 "open"

 

[shindemac]

I believe that knowing how closed the racket face is at the initial contact is a very close call and that you would have difficulty making a reasonable case by "Look at any pro serve at the point of contact." The requirements for just knowing the point of contact are quite a trick. How would you do that, what equipment, etc.?

It's open. Do you see the 2 blue lines that are drawn to show the angle. The angle is not even close to 180 degrees. It's open near contact, and way after contact. IOW, it's open at contact. Anyways, I don't have time to argue stupidity. Anyone with their own eyes can see. Even a first grader can understand what happens at contact, even if the exact frame isn't shown.

 

[sureshs]

It's open. Do you see the 2 blue lines that are drawn to show the angle. The angle is not even close to 180 degrees. It's open near contact, and way after contact. IOW, it's open at contact. Anyways, I don't have time to argue stupidity. Anyone with their own eyes can see. Even a first grader can understand what happens at contact, even if the exact frame isn't shown.

Exactly what I said in post #6. Whether Raonic is extended into the court or not, the racket face is still open, and not pointing down as Tomaz claims.

 

[sureshs]

See Pat Cash teach the serve here. Drag the arrow thingie to advance the frames. You can make it pause at contact - it is about 2/3 rds of the way in. The racket has just gone over the cusp.

http://www.bbc.co.uk/guides/zgppfg8

 

[Raul_SJ]

I wouldn't call 3 "open"

The dwell time on the strings is 5 milliseconds, so we cannot make any conclusions based on two frames of a low frame rate video.

And what is the significance if it is tilted one degree either way at contact?

The swing path is decidedly upwards, so it is best to think of it as "hitting up", even if that does not physically happen at contact.


See Toly's high frame rate video at contact. "Racquet hits the ball 6000fps Super slow motion".

 

[sureshs]

it is best to think of it as "hitting up", even if that does not physically happen at contact.

That is your way of looking at it. Others may prefer to align their thinking with what really happens.

 

[Raul_SJ]

That is your way of looking at it. Others may prefer to align their thinking with what really happens.

One degree closed at contact. One degree open at contact. Vertical at contact.

How does that minute difference affect your instructional cue for the overall serve? Players are not sensitive enough to feel such a tiny difference.

 

[Ash_Smith]

Coaching cues - like "try to feel like you are swinging up" are not necessarily exact statements to describe the physics of the swing, they are simply ways of translating the info to an athlete who has an issue with a particular aspect of the swing.

Give this thread to a novice player and tell them "At the end of the dwell time, the racket may have crossed the apex and the perpendicular to the strings in the deformation zone may be pointing ever so slightly downward. It is even more subtle because the plane of the deformation zone need not be parallel to the plane of the strings but slightly skewed."

Or, tell them "try to feel like you're throwing the racquet up to the ball" and we'll see which has the biggest impact on their ability to get the ball in the box

 

[Raul_SJ]

Coaching cues - like "try to feel like you are swinging up" are not necessarily exact statements to describe the physics of the swing, they are simply ways of translating the info to an athlete who has an issue with a particular aspect of the swing.

I agree. Just wondering why some seem to be concerned with whether the racket is tilted plus or minus one degree at contact. It is a very minute difference
and the difference is too small to physically feel. Nobody is able to contact a serve one degree open or one degree closed...

In any case, looking at the 6000fps Toly video posted above, it looks like the racket is vertical, or perhaps 1 degree slightly closed at intial contact.

Would you agree with this?

 

[Ash_Smith]

^^^ I think it largely depends on how you personally define open or closed in the context of a serve. I believe in the original article there was talk of the palm of the hand being in an "open" position at contact, which is entirely possible depending on the grip.

 

[Raul_SJ]

I am defining open/closed in terms of the racket, not the hand. And it seems clear from the video above of the 140mph serve, that the strings are vertical or slightly angled down at contact, but certainly not open for that 140mph serve.

The racket face will be basically vertical for flat serves and perhaps slightly closed in extremely fast serves.

But the coaching cue should always be to "hit up on the serve", since I assume the common error for club players is hitting down on the serve. Most of the faults I see are into the net.

 

[ARKustom93]

It goes downward?

Your post brings out an important point that the racket head may appear to be vertical or even a little bit open, but the asymmetrical string deflection actually exerts a downward force. This explains the conundrum frequently cited on this forum: If the ball is not being hit down, why is it angled slightly down (on traditional first serves)? Gravity alone cannot explain it. I have been discussing this for years on this forum and it is nice to see good analysis come up. In the past, only personal insults would result.

What happens is over a period of time, pros (and rec players too) have found out how to exploit this, albeit sub-consciously. They "know" where to contact the ball and at what speed so that they can be hitting at vertical or even upwards, but bringing their racket tip quickly over the apex during the dwell time to give the asymmetric string deflection effect. When they go wrong, they put the ball into the net or long. If they are too careful, the serve is too slow. This is the real reason why pros have ridiculously low first serve percentages (compared to say table tennis or badminton). As 5263 said, much is happening at contact than meets the naked eye.

If you position the rubber band vertically and set the projectile above center for the pull(perpendicular to band orientation), yes.

Re the second part of your comment: That first sentence addresses an important point. I look at the evolution of virtually all technical components involved in hitting a tennis ball(footwork/stances, stroke-mechanics, grips, kinetics, you name it) as a journey of accidental discovery. Since we're talking serves, take Andy Roddick's for example, quite unique at the time, and all the way down to his 'footwork'(he leaves a small gap in the pinpoint stance, and actually pulls his front foot back toward the back foot before push-off). Anyone think that serve came out of a lab, so to speak? No, he 'found' something that worked, stuck with it, and refined it. And you could make a sheer endless list of 'Aha' moments throughout tennis history ...

 

[Chas Tennis]

Everyone can find a number of pictures that seem to support their views, also known as 'cherry picking'.

I don't recall seeing research of a number of good serves from high level servers to show us stats on how open or closed the racket is at initial contact. Effective servers miss 30-40% of their serves, so showing a single picture where you don't even know if the serve was good or not does not help answer the question -

How open or closed is the racket at the initial contact for the average high level serve?

The racket might be closing at a rate as high as 2° per millisecond before impact so very high speed video is necessary to properly see this. Most high speed videos of serves are 200-300 fps - not very high speed. At 240 fps, a frame is capture every 4.2 milliseconds. Therefore the racket face may be closing as much as 8° during the 4.2 milliseconds between frames.

This video at 420 fps illustrates that the first frame that the ball is observed on the strings the racket is about neutral while 2.4 milliseconds earlier the racket face is open. It could have been open at initial impact. ? Whether the serve was good is not known.

Frame 2.4 milliseconds before impact. Racket is open.

First frame showing ball on strings. The racket is slightly closed. The leading edge of the ball has just begun to move based on using the fan's leg in the background as a reference. ISR has rotated the racket head and the swing has tilted it forward in these 2.4 milliseconds. The change in the angle seems larger than it should be in 2.4 milliseconds. ?

See #17 for source of estimated racket closing rate.
http://www.spalla.it/handout/2012_aprile/ELLIOTT_Biom_of_serve_Italy_20_m.pdf

Frames are caught at random times by high speed video. Exactly when a frame is exposed is always unknown.

For the first frame that shows the ball in contact with the strings (see Assumptions below) :

1) If the racket face is open (oriented up) then it was probably more open at initial contact. (This makes it much easier to use high speed videos to argue that the face is open at initial impact.)

2) If the racket face is closed (oriented down) then it was probably less closed or open at initial contact. You have to consider how rapidly the racket is closing and the camera's frame rate. (This makes it more difficult to use high speed videos to argue that the racket face is closed at initial impact.)

If a neutral sample (no cherry picking) of good serves can show the racket face open in the first frame with contact, then that is a good case.

If a neutral sample of good serves can show the racket face closed in the first frame with contact, then more work has to be done to argue the face is closed for the initial contact.

I've looked at a lot of the first frames that show ball impact. I mostly do not know if the serves were good. My rule of thumb is that the the racket is within a few degrees of vertical. I'd like to know more on the issue based on research.

I don't have a clear idea of what "hit up on the ball" means. I also did not see that Tomaz discussed this level of detail for the angle of initial contact.

Assumptions for above:
1) Assume that the frame exposure time is very short compared to the time between frames and motion blur is very small.
2) Jello Effect distortion is not considerable in the high speed video. This issue has to be known for certain cameras because it might falsely make the racket appear bent. This issue has caused big problems and embarrassment in golf by falsely bending gold club shafts.
3) The racket has not been distorted or considerably tilted by the impact. From the 6000 fps video this might be an issue for accuracy.

 

[Chas Tennis]

Another factor -

The toss height causes a considerable variation in the downward velocity of the falling ball. For example, in order to produce a similar serve, because of her high toss, Sharapova's racket face would have a different angle than the racket face of a server with a low toss.

 

[sureshs]

The original post is not about coaching instructions but what really happens. I think the two should not be confused. Any coach can claim that he is always correct because he is talking about "feel" so there is no point going there, like the infamous wrist snap or hitting below the center

 

[Raul_SJ]

If the dwell time is 3 milliseconds, 420fps video would seem insufficient. It could miss a millsecond and 2° of rotation.

I presume Toly's 6000fps 142mph serve video is a pro serve which landed in. Typically, only good serves are measured and recorded by radar.

The slight degree of variation at contact is likely random, Similar to the "Hit below center" forehand issue. It may happen, and arguably result in greater topspin, but not likely intentional. Even more so in the case of the serve, since we are discussing very subtle variations (+1° closed to -1° open).

 

[Chas Tennis]

I'd say that good information on this issue is not at hand.

I started looking at first frames of serves for random servers. I selected them by: being prominent players or someone that was likely to be a pro, high speed video with small motion blur, I thought that the ball was on the strings, side views only, and I thought that I could tell what was vertical by something in the video, a pole or rail, etc.

Serena Open
Federer Closed
Unknown from forum, Closed
Murray Closed
Unknown Neutral

As I discussed, an "Open" finding is racket Open. But a "Closed" finding might be false unless some other information is examined. I imagine if any reader looked at 10 high level serves they would get an idea of how things would come out if it were done more carefully.

To get some serves to analyze -

There are several videos with side views on my Vimeo collection.
https://vimeo.com/user6237669/videos/sort:likes/format:thumbnail
You can do stop action by holding down the SHIFT key and using the ARROW keys.

Google: tennis serve ball racket images
Try other searches for images or pictures such as Toly - Anatoly Antipin images

 

[donquijote]

The server doesn't really hit upwards but the feeling and the arm movement feels like hitting upwards but the body is moving towards the net and it is creating an angle that secures landing on the other side if the timing of the contact is good.
As much as I like Tomas, some of his videos are really confusing. There is no need to talk about hitting upwards really. Maybe he is trying to clarify a myth but why waste time on it?