Salazar & Stosur serve - Comparison of body rotation about spine

toly

Hall of Fame

Figure 1. Salazar flat serve ad court – body rotation about the spine


Figure 2. Stosur topspin serve ad court – body rotation about the spine

Frank Salazar rotates his body 125°, but Sam Stosur only 45°. This is really enormous difference. :shock:

Pictures were copied from FYB and Chas Tennis videos.
 
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Roy125

Professional
Seems like Salazar is hitting a flat serve while Stosur is hitting a kick serve. This might account for the difference.
 
Is the Salazar serve identified also as a kick serve?

In the Stosur's serve, I believed that the serve was a kick because the bounce appeared very high and to the right.

In that frame, Stosur reaches much more of the 'chest up' position than Salazar, her racket is tilted back and her knees are bent. Stosur is later into her serve motion than Salazar.

We should compare when Salazar's racket is tilted back and his knees are bent ready to thrust or thrusting. How much knee bend does Salazar get for that serve?

In Elliott's book, three trunk motions are identified:

1) Shoulder-over-shoulder - cartwheel
2) Twist
3) Forward - somersalt axis

Maybe some servers use considerably different amounts of each trunk motion. Stosur's motion for the kick serve would definitely be an extreme. Maybe Salazar uses more turn and she has more chest up motion for the kick serve. ?

Technique Development in Tennis Stroke Production,(2009) B. Elliott, M. Reid, M. Crespo (available only from the ITF)


I see more of the rotation point made by the OP - Using Elliott's motions: Stosur has

1) the normal amount of shoulder-over-shoulder
2) but does not appear to have much Twist rotation
.
3) The forward - somersalt axis motion is not well shown from behind. Also, she appears to be reaching straight up at impact but there is a large angle between her body and arm that does not show because it is away from the camera (the old 2D camera view of a 3D space problem - it's even mentioned in Elliott's book as a difficulty for observing these trunk motions)
 
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toly

Hall of Fame
Seems like Salazar is hitting a flat serve while Stosur is hitting a kick serve. This might account for the difference.
Here are pictures of Salazar body rotation for different serves.





 
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boramiNYC

Hall of Fame
I'm not a fan of stosur's serve technique. she is going for maximum spin, which she is known for, for the cost of a good flow in the kinetic chain. she seems she has to hold back the rotational portion of the chain and toss way back in order to achieve max spin. the results is a massive kick serve but also many double faults at the most pressure situations.

I really hope people stop using her serve motion photos since there are plenty better examples to learn from.

in reg to OP's comparison, salazar's serve is far better model to learn from.
 

toly

Hall of Fame
The slice serve shows impact the farthest back over his head. Isn't this what they recommend for the kick serve. ??
Yes, you are right. I corrected pictures. :cry:
Pros always strike a ball downward (serve angle A), but this angle is function of outgoing ball speed and spin. Usually slice serve has minimal speed and maximum spin. The spin increases the path, so, the path of the ball to target is longest and takes more time. To compensate that, we should decrease serve angle.

In case of flat serve, the ball speed is maximum and spin is zero. Then Salazar has to create maximum serve angle and meet the ball the farthest in front of him to close the racquet head.
 
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Lukhas

Legend
180° would mean that she did an half turn. Which means that she would end her service motion facing the left side of the court... or that she started her service motion turned back from the net. However she hips are facing the net. And knowing her service motion, I know the first proposition isn't correct either.

Tl; Dr: Nah she didn't do a 180° turn.
 

toly

Hall of Fame
180° would mean that she did an half turn. Which means that she would end her service motion facing the left side of the court... or that she started her service motion turned back from the net. However she hips are facing the net. And knowing her service motion, I know the first proposition isn't correct either.
Tl; Dr: Nah she didn't do a 180° turn.
What can you say about these pictures?



can you still do this if you have back problems ?
With computer I can do it. :)
 

Lukhas

Legend
What can you say about these pictures?
1) That they're very pixellated;
2) That it isn't a 180° body rotation to the baseline. You can see her upper back isn't fully facing the net. It would be more visible if we had the opposing viewpoint.
You wrote the OP, I didn't. I'm only using your words.
Figure 1. Salazar flat serve ad court – body rotation about the spine
Figure 2. Stosur topspin serve ad court – body rotation about the spine
 
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toly

Hall of Fame
1) That they're very pixellated;
2) That it isn't a 180° body rotation to the baseline. You can see her upper back isn't fully facing the net. It would be more visible if we had the opposing viewpoint.
You wrote the OP, I didn't. I'm only using your words.
I have problem with English. How should I call this rotation? :(
 

Lukhas

Legend
I'm not better at English believe me. It's the language of my country's enemies... :lol: EDIT: All I can tell you is that it would be really hard to have a 180° body rotation on serve.

Since you're interested in body rotation, maybe you should watch this video about Roddick's serve.
http://www.youtube.com/watch?v=pLf_MJXzBVg
 
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Maybe some servers do turn a lot more than others. ? I'll have to put it on my lookout list.

A single video of one serve is better. You can't even tell on the left Venus serve which court she is serving into. Or, for either picture, whether it is singles or doubles.

We could go back to McEnroe to determine what is humanly possible......
 

toly

Hall of Fame
Maybe some servers do turn a lot more than others. ? I'll have to put it on my lookout list.

A single video of one serve is better. You can't even tell on the left Venus serve which court she is serving into. Or, for either picture, whether it is singles or doubles.

We could go back to McEnroe to determine what is humanly possible......
This is Serena’s slice serve with a lot of body rotation.

 
serena has a technically perfect serve. every bit as good as federer or sampras (just technique of course the men have more power). that is very rare at the WTA.
 

LeeD

Bionic Poster
Serena is 5'10" tall.
Fed and Sampras closer to 6'1".
With that 3" of extra height, the REACH can be well over 6", possibly as much as a foot, for increase leverage.
For example, I'm 5'11", or a 1/4" shy now that I'm 64. My contractor is 6'1" tall. His standing reach, flat footed, is well over 9" higher than mine. He reache's over 8'2", while I only reach 7'4".
Another thing, feetsize. Big feet can help raise your body for higher contact point, leading to better and higher percentage of getting serves, especially fast ones, IN.
I'd guess Serena has big feet for a woman, but Fed and Sampras had shoesize 11.5, which is like size 13 in women's sizing.
 
This is Serena’s slice serve with a lot of body rotation.

Back turn to impact, I'd estimate that serve as 100° more or less. That's about what I would guess applies to most servers, maybe a little more.?. I have not looked over a large number of servers to get a better estimate.

The follow though is after impact and may be more variable. ?

The amount of motion and or stretch is the interesting thing. Elliott lists and discusses these separate motions:

1) Leg drive
2) Hip Rotations
3) Separation angles between hip & shoulder alignments.
4) Hip Thrust
5) Trunk - Shoulder-over shoulder 'cartwheel'
6) Trunk - twist
7) Trunk - Forward 'somersault' axis.

These are discussed in Technique Development in Tennis Stroke Production, Elliott, Reid, Crespo. They also discuss developmental guidelines for these motions for younger players.

Maybe it is easier to just 'feel' the serve...?............
 
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RetroSpin

Hall of Fame
Serena is 5'10" tall.
Fed and Sampras closer to 6'1".
With that 3" of extra height, the REACH can be well over 6", possibly as much as a foot, for increase leverage.
For example, I'm 5'11", or a 1/4" shy now that I'm 64. My contractor is 6'1" tall. His standing reach, flat footed, is well over 9" higher than mine. He reache's over 8'2", while I only reach 7'4".
Another thing, feetsize. Big feet can help raise your body for higher contact point, leading to better and higher percentage of getting serves, especially fast ones, IN.
I'd guess Serena has big feet for a woman, but Fed and Sampras had shoesize 11.5, which is like size 13 in women's sizing.
Interesting points Lee. Fed also jumps very high, much higher than Serena. That's a huge difference with non-Tour level players, particularly the older guys. No one jumps.
 

LeeD

Bionic Poster
I don't jump, but do get up on my toes...slightly higher than the balls of my feet. Lucky for me, I'm sized 10.5, so get up a bit.
Some opponent's 27 years ago say I always jumped about a foot or slightly higher back then, ancient history.
And wingspan can affect leverage for hitting by a ton.
I am 5'11" tall, but only wingspan 5'10". My swimmer bud, at 6'1", has a 7' 2" wingspan. If he played tennis, he'd have incredible leverage to hit serves hard.
 

toly

Hall of Fame
serena has a technically perfect serve. every bit as good as federer or sampras (just technique of course the men have more power). that is very rare at the WTA.
There are Federer flat and kick serves with very small body rotation (trunk-twist) wrt Williams sisters:
1. Flat - Body rotation <90°.
2. Kick – Body rotation ~45°.



 
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LeeD

Bionic Poster
EVERYONE hits their serves differently.
There is NO such thing as ONE technique that works best for everyone.
 
I wish we could find some research.

I believe that several or all of the Elliott motions might cause stretching of the ISR muscles. Since the ISR muscles can only be stretched so far probably a server can use more or less from each of the motions. Recall the thread for serving from the knees with no leg thrust and still getting good pace? It doesn't '......all come from the legs......' then.

Reply #20-
"The amount of motion and or stretch is the interesting thing. Elliott lists and discusses these separate motions:

1) Leg drive
2) Hip Rotations
3) Separation angles between hip & shoulder alignments.
4) Hip Thrust
5) Trunk - Shoulder-over shoulder 'cartwheel'
6) Trunk - twist
7) Trunk - Forward 'somersault' axis. "
 
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RetroSpin

Hall of Fame
I think it is fair to say there are two approaches to this. I would argue that the Fed approach defines the modern serve, which emhasizes vertical movement and the bowed left hip which straightens to propel the the right shoulder forward.

The Williams sisters have a more old school rotational move. I think teachers that begin students with throwing racquets, etc, will end up producing this type of motion.
 

toly

Hall of Fame
I wish we could find some research.

I believe that several or all of the Elliott motions might cause stretching of the ISR muscles. Since the ISR muscles can only be stretched so far probably a server can use more or less from each of the motions. Recall the thread for serving from the knees with no leg thrust and still getting good pace? It doesn't '......all come from the legs......' then.

Reply #20-
"The amount of motion and or stretch is the interesting thing. Elliott lists and discusses these separate motions:

1) Leg drive
2) Hip Rotations
3) Separation angles between hip & shoulder alignments.
4) Hip Thrust
5) Trunk - Shoulder-over shoulder 'cartwheel'
6) Trunk - twist
7) Trunk - Forward 'somersault' axis. "
According to Bruce Elliot, see tennisplayer.net article, The Power Serve: Part 1, there are three forms of trunk rotation.

1. Forward rotation, like I’m going to do somersault.
2. Twist rotation around a spine.
3. The back shoulder rotation over the top of the front shoulder, as in a cartwheel.
The most important is #3.

All servers use cartwheel rotation practically the same way, but why there is so big difference in trunk twist rotation? Williams sisters use it extremely hard and they are the best servers. Maybe twist rotation around the spine is (or could be) the most important serve motion.
 
In the 70's and 80's, I believe there was a lot more discussion of the 'American Twist' serve. I am still not clear on the distinction between the kick serve and the American Twist serve but the 'American Twist' term seems to have fallen out of usage. I recall that the American Twist had a reputation for being stressful on the back, causing injury, etc.. The Health & Fitness Forum does not seem overwhelmed with back injuries from the American Twist serve. ? Maybe some others remember this issue?

Anyway, the cartwheel involves lateral flexion of the spine. The somersault might involve the hips or back (if rounding forward) ? The trunk twist is "lumbar rotation" - this seems the most stressful to me. Maybe it gets too busy and servers tend to emphasize some motions over others.

Not young, I decided to minimize using my back, especially somersault and twist motions, to make it easy on my back. I also notice some strong servers seem to serve with a quiet back, Raonic. I'll have to double check that impression in some high speed videos.

Raonic serve, this one looks like a quiet back serve to me. - (I have not looked at many for back motion.)
https://vimeo.com/63688134
 
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Figure 1. Salazar flat serve ad court – body rotation about the spine


Figure 2. Stosur topspin serve ad court – body rotation about the spine

Frank Salazar rotates his body 125°, but Sam Stosur only 45°. This is really enormous difference. :shock:

Pictures were copied from FYB and Chas Tennis videos.
I feel Salazar and Stosur try to shoulder/arm muscle the serves more while Federer's body is way more relaxed. He was still going up right and kid of doing a mini crunch with his abs at contact while stosur's body is pretty much straight and swinging.
 

toly

Hall of Fame
I feel Salazar and Stosur try to shoulder/arm muscle the serves more while Federer's body is way more relaxed. He was still going up right and kid of doing a mini crunch with his abs at contact while stosur's body is pretty much straight and swinging.
I don’t see noteworthy differences between Stosur and Federer body actions.



 
Federer's legs are not straightened like Stosur's. It looks like he's doing a crunch.
Okay, if you want to get really nitpicky, Federer bends his knees a bit at the top of his jump, which probably gets him a bit more hangtime. But there are no fundamental differences between the two of their serves.
 

RogueFLIP

Professional
If you didn't watch the video Lukas linked in post # 15, you should really pay attention to the differences in the hip flexors/rotators.

Video shows how an increase in the range of motion in your hips utilized in the serve acts as a force multiplier further up the kinetic chain. Obviously you also need an efficient use of each chain of the body parts together, which Roddick has.

But increasing just a few degrees of hip rotation can increase power produced 16X, if I recall the video correctly. That's a lot of free power for a little ROM.
 

toly

Hall of Fame
Lisicki possesses 130mph serve and like Venus twist the trunk nearly 180°. So, all WTA fastest servers can twist their trunk like crazy, but Federer cannot, that’s why he has so “slow” serve (just 135mph)!!!??? :shock:

 

TennisCJC

Legend
Okay, if you want to get really nitpicky, Federer bends his knees a bit at the top of his jump, which probably gets him a bit more hangtime. But there are no fundamental differences between the two of their serves.
There's a tennis oxygen analysis of Federer's flat and kick serves - side by side video. The guy talks about how Federer continues upward more thru his kick serve. The knees lift AND his body continues upward - he get slightly higher on the kick.
 

Lukhas

Legend
Please, please. When you talk about angles, know what you're talking about. This is a 180° angle. Good luck obtaining that with your spine/hips/trunk/delete as appropriate if you're no contortionist.


And for reference, I'll repost once again the serve analysis of Andy Roddick that explicitly talks about hip rotation. Forget about the spine thank you. It's the hips we're talking about, and the trunk as a whole. EDIT: Rotating around your spine would mean that your spine doesn't move and your whole body is rotating around it. Pretty unhealthy if you want my opinion. That's workd nitpicking of course, and this from a non-fully fluent Frenchman. But let's just say "hip rotation". Much simpler. No need to make knots with your brain.
http://www.youtube.com/watch?v=pLf_MJXzBVg
Yes Lisicki has excellent hip rotation compared to her WTA counterparts (besides the Williams). But close to 180°? Please, no. Say, another video about WTA and ATP serve differences if you're really into it.
http://www.youtube.com/watch?v=v8q2cBx19ec
 
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You guys are seriously overanalyzing things. Every pro you mention has a great serve, and you should be looking at the things they all do, not things only a few of them do. Attempting to swivel your hips like Roddick or jump up like Federer will not get you anywhere.
 

toly

Hall of Fame
Please, please. When you talk about angles, know what you're talking about. This is a 180° angle. Good luck obtaining that with your spine/hips/trunk/delete as appropriate if you're no contortionist.
This is my measurement. Maybe you can do better?


Lisicki first serve
 

Lukhas

Legend
This is my measurement. Maybe you can do better?
I can tell you what I think is wrong. Her body faced roughly where your right arrow his during her trophy pose. But her boody is then facing the court at impact. If she had done a 170° turn towards where your left arrow is, you would clearly see her face, chest, heck, all the front of her body pointing where your left arrow is. Her body didn't do such a turn. It's a bit over 90° of body rotation, maybe 110°, not almost the double.

A 180° turn is a U turn. Did she do a U turn or something close to it? Clearly not. That's why I think your measurement is wrong. She didn't do a U turn, therefore her whole body hasn't done a 180° rotation. See the Roddick vid to see how his body rotation was calculated for reference.
 
Toly, Are you getting those red lines for the chest by estimating how the chest is pointing? Or are you drawing a line between the two shoulders and taking a perpendicular to it?
 

toly

Hall of Fame
I can tell you what I think is wrong. Her body faced roughly where your right arrow his during her trophy pose. But her boody is then facing the court at impact. If she had done a 170° turn towards where your left arrow is, you would clearly see her face, chest, heck, all the front of her body pointing where your left arrow is. Her body didn't do such a turn. It's a bit over 90° of body rotation, maybe 110°, not almost the double.

A 180° turn is a U turn. Did she do a U turn or something close to it? Clearly not. That's why I think your measurement is wrong. She didn't do a U turn, therefore her whole body hasn't done a 180° rotation. See the Roddick vid to see how his body rotation was calculated for reference.
In the video they discuss pelvis rotation, but I’m talking about shoulder rotary motion wrt ground.

Toly, Are you getting those red lines for the chest by estimating how the chest is pointing?
This is correct.
 
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