Contribution of leg drive in racket head speed on serve

Digital Atheist

Hall of Fame
I think the latter part of this is key. "Earlier activation" of lower body muscles. If you watch videos of pro serves, they use leg drive to initiate the racquet drop out of trophy. Their knees are fully extended as the racquet reaches full drop.

The average rec player thinks of it differently. Even some WTA pros have the concept wrong. These players think leg push is used to help shotput the racquet up to the ball. Hence they fire their legs later than elite servers.

Push versus pull anyone?? Radical concepts like the kinetic chain are discussed in the following article, so it might not be for everyone, but I found it interesting:

http://www.aspetar.com/journal/viewarticle.aspx?id=6

And then there's this, which seems connected:

 
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WildVolley

Legend
One thing I've noticed is that because of the passive nature of the liftoff, the liftoff itself is not a mandatory part of the serve, even though the knee bend itself is mandatory. Liftoff should only happen if you are swinging fast enough that your racquet + arm will naturally literally pull up the rest of your body into the air via the "centrifugal" force caused by such a violent swing. This is why when you see pros like Federer warm up their serve (ie hitting puff serves with correct technique), they barely lift off the ground. However, even those puff strokes create enough force to straighten out their knees up to contact, allowing them to make the necessary contact up in front and up high.

I do not believe this description. The racket and arm do not weigh enough and aren't moving fast enough to "lift" the body into the air.

People go into the air because they're pushing off the ground with their feet. Perhaps if we call this hopping rather than jumping it will be more acceptable to tennis players, but we shouldn't perpetuate the myth that the swing is lifting the body. It is pushing off the ground that is adding some stretch to the muscles used in the swing during the drop and the same pushing off the ground that moves the body into the air.

I'm a believer that tennis players and instructors should just admit that people are going into the air because of what is called in other sports "jumping." If we don't admit it, we're left with implausible momentum theories.
 

Bender

G.O.A.T.
I do not believe this description. The racket and arm do not weigh enough and aren't moving fast enough to "lift" the body into the air.

People go into the air because they're pushing off the ground with their feet. Perhaps if we call this hopping rather than jumping it will be more acceptable to tennis players, but we shouldn't perpetuate the myth that the swing is lifting the body. It is pushing off the ground that is adding some stretch to the muscles used in the swing during the drop and the same pushing off the ground that moves the body into the air.

I'm a believer that tennis players and instructors should just admit that people are going into the air because of what is called in other sports "jumping." If we don't admit it, we're left with implausible momentum theories.
That's exactly why if you aren't swinging for the fences, you don't lift off the ground.

I lift off the ground on most of my serves, but when I'm warming up, both feet are planted on the ground.

You also have to remember that whilst I said that the liftoff is caused by the racquet and the arm, you're still really throwing your entire body, in particular your upper torso with them at the ball. Hence the pull from the ground.

If you hop or jump into the ball on purpose, you really can't make contact consistent enough. Especially if you aren't swinging fast enough to necessitate the jump.
 

WildVolley

Legend
That's exactly why if you aren't swinging for the fences, you don't lift off the ground.

I lift off the ground on most of my serves, but when I'm warming up, both feet are planted on the ground.

You also have to remember that whilst I said that the liftoff is caused by the racquet and the arm, you're still really throwing your entire body, in particular your upper torso with them at the ball. Hence the pull from the ground.

If you hop or jump into the ball on purpose, you really can't make contact consistent enough. Especially if you aren't swinging fast enough to necessitate the jump.

I stand by the claim that you are not lifting off due to racket and arm momentum.

I think it is safer to say that subconsciously you are focusing on swing speed and perhaps pushing your chest up toward the ball, but to generate that swing, you are pushing harder off of the ground and, ultimately, it is the pushing off the ground that is causing you to move into the air.

Usually, to be effective, the leg drive/push/hop needs to be timed to accentuate the racket drop and, since there's a twisting motion during the hop of good servers, it should feel as though it is part of the swing.
 

Chas Tennis

G.O.A.T.
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You also have to remember that whilst I said that the liftoff is caused by the racquet and the arm, you're still really throwing your entire body, in particular your upper torso with them at the ball. Hence the pull from the ground.
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fjey41.jpg


The arm and racket aren't lifting the body off the ground. The momentum given to the entire body mass by the legs is lifting the body off the ground.
 

Raul_SJ

G.O.A.T.
This is contradictory since "good mechanics" include leg drive. Without the leg drive. the kinetic chain (mechanics) is incomplete. Consider this. I can hit a very fast FH w/o using leg drive and with almost no rotation (uncoiling) of the body.

Is this advisable on a regular basis? Does this illustrate that the leg drive and body rotation on the FH are superfluous? Of course not. Hitting big/fast FHs using just the shoulder and other parts of the arm undoubtedly put considerably more stress on the shoulder/arm than using a full KC would. The same is true if we minimize the use of GRF and leg drive on the serve. We can still hit big serves but it means that the shoulder and other body parts must assume a greater role in generating RHS. Ultimately, it puts more stress on the shoulder if leg drive is minimized.

Note that Stan Wawarinka is regarded to be unusually strong & powerful. His shoulder appears to be rather thick and solid. However, he was still plagued with shoulder issues in 2015 (do not know if it has bothered him significantly this year). His shoulder bothered him during/after Wimbledon 2015. It also forced his to withdraw from Gstaad, his own/home (Swiss) Open. His shoulder issues, despite his strong/massive shoulders, may or may not be related to his lack of leg drive on his serve.

I don't know if that necessarily follows. I had been hitting relatively powerful forehands for years without employing the proper knee bend and coiling found on high level forehands. These "Non Kinetic Chain forehands" were ~55mph-60mph but I never experienced any stress on the arm. I made sure to keep my arm loose and relaxed and I did not have the feeling of "arming" the ball or trying to overswing.... I then started to utilize more of the kinetic chain by coiling more (still did not incorporate much knee bend). The "Kinetic Chain FH" was ~60-65mph...

As it relates to the serve, Wawrinka seems to have the same leg drive as Gonzales, so I am not convinced that Wawrinka's lack of leg drive places more stress on the shoulder.
Rick Macci videos mention that "bending the knees makes the racket go faster". I agree but I also think that at the serve contact point, the leg drive is mostly out of the picture. At contact point, the arm is mainly doing the work.

If I understood the Elliot study correctly, they were expecting to find less load on the shoulder when employing leg drive serve and more load on the shoulder when using a minimal leg drive "ARM " serve. But their findings did not confirm this. Yes, employing the leg drive did increase RHS, but that increased RHS was also associated with greater forces on the shoulder. (Is my understanding on this correct?).

Interestingly,comparable shoulder joint kinetics evolved from the differential lower-limb mechanics that characterized the FU,FB,and ARM techniques,indicating that the link between leg drive and shoulder joint loading may not be strong as previously thought. Indeed,the noted dichotomy in the resultant racket velocities between serves could point to serve speed increasing along with pre-impact shoulder joint load.

33fte8M.png

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Chas Tennis

G.O.A.T.
When things get too complicated to understand in detail - we see research is still being done to understand these issues in more detail - we can always keep in mind what the best servers are doing.

The current strong ATP servers use
1) Leg Thrust
2) Cartwheel (or shoulder-over-shoulder)
3) Trunk Twist
4) Somersault, a forward body bend (stretch?)
..others...

These are used for the same reason when it comes to the shoulder - to force external shoulder rotation (ESR) that first lengthens and then stretches the internal shoulder rotation (ISR) muscles.

I have not seen research that claims some measure of the percentages of stretch produced by each motion. I did see in some references that Cartwheel quality was believed to be most associated with the best serves. ? Since each of these motions can be used to pre-stretch ISR muscles and they are used at about the same time, who knows how much of each is used by an individual strong server? Little less leg thrust and a little more Cartwheel.............?.......

One nice thing about breaking down the serve into those component motions is that they are crystal clear in high speed videos for all to see. The basic timing is clear and so is its variation among servers. There are indications of the relative strength or weakness of each component too but that is not so obvious.

The above is not a complete description of the serve, there are other motions adding to racket head speed.
 
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Fxanimator1

Hall of Fame
Getting back to Pancho if the only reason for the knee bend is to raise contact height why would Pancho bend his knees--he has to keep one foot on the ground and his contact height is limited by that.
Uh-Oh!...You had to go and apply logic to this discussion.
 

SystemicAnomaly

Bionic Poster
I don't know if that necessarily follows. I had been hitting relatively powerful forehands for years without fully employing kinetic chain (less than optimal knee bend and coil), but I never experienced more stress on the arm. I only observed less RHS as compared to greater RHS when fully utilizing the kinetic chain.

As it relates to the serve, Wawrinka seems to have the same leg drive as Gonzales, so I am not convinced that Wawrinka's lack of leg drive places more stress on the shoulder.

If I understood the Elliot study correctly, they were expecting to find less load on the shoulder when employing leg drive and more load on the shoulder when using an "ARM " serve (serve without leg drive). But their findings did not confirm this. Employing the leg drive did increase RHS, but that increased RHS was also associated with greater forces on the shoulder.

Interestingly,comparable shoulder joint kinetics evolved from the differential lower-limb mechanics that characterized the FU,FB,and ARM techniques,indicating that the link between leg drive and shoulder joint loading may not be strong as previously thought. Indeed,the noted dichotomy in the resultant racket velocities between serves could point to serve speed increasing along with pre-impact shoulder joint load.

33fte8M.png

E5YiNwp.png

i've got a couple of thoughts on this. Will post a reply a bit later.
 

THE FIGHTER

Hall of Fame
On serve, try hitting a bucket of balls without the leg drive. Only use the upper body and good technique. Better yet, start from the power position so you cant rely on any momentum. But maintain good form. Then reintroduce the legdrive. What i found is you get so much "easy added power" from the leg drive, especially when the upper body has the right mechanics. The first few serves(kick) cleared the net by 6 feet but barely missed the lines.
 

THE FIGHTER

Hall of Fame
I do and will always believe the secret to pete's serve was his legs. Forget jumping, Pete didn't jump as high as Fed or some other players. Look at how much core rotation Pete had, if you have tried to emulate this, the leg drive REALLY helps, I don't know why but it does. Just do it.
Pete also had his hips in a deep archers bow when he gets in his power position. The smooth progression on his kinectic chain is also perfect, maximizes power with the least amount of resistance.
 

Aretium

Hall of Fame
Pete also had his hips in a deep archers bow when he gets in his power position. The smooth progression on his kinectic chain is also perfect, maximizes power with the least amount of resistance.

This is hard to do though, I tried doing it last season with the hips into the court on the platform stance. Quite difficult and it is a little strenuous on the hips and the front knee. I also didn't find the benefit from it but it probably messed up my timing. I'm not pete. I still put my hip into the court but not as much.
 

Chas Tennis

G.O.A.T.
Pete also had his hips in a deep archers bow when he gets in his power position. The smooth progression on his kinectic chain is also perfect, maximizes power with the least amount of resistance.

Pete uses the technique where he moves through Trophy Position. Many other servers also pause at Trophy Position. Those are two common variations of the high level serving technique that can easily be seen in high speed videos. Pete's Trophy Position is an instantaneous position while other servers may be near TP for several tenths of a second.

It is hard to understand the serve using just the kinetic chain concept because simply speeding up smaller body parts sequentially, next 'segments', does not explain what is going on with the stretch shorten cycle.

The research in the 1990s by Marshall, Elliott et al recognized something was wrong with the kinetic chain concept for internal shoulder rotation (a defined shoulder joint motion where the shoulder joint does not necessarily move anywhere). They refer to ISR as "The missing link......"

Marshall & Elliott pointed this out several times in their early publications on internal shoulder rotation ("long axis rotation").

Long-axis rotation: The missing link in proximal-to-distal segmental sequencing

https://www.researchgate.net/profil...sequencing/links/004635393c2ce077ab000000.pdf
 
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THE FIGHTER

Hall of Fame
Pete uses the technique where he moves through Trophy Position. Many other servers also pause at Trophy Position. Those are two common variations of the high level serving technique that can easily be seen in high speed videos. Pete's Trophy Position is an instantaneous position while other servers may be near TP for several tenths of a second.

It is hard to understand the serve using just the kinetic chain concept because simply speeding up smaller body parts sequentially, next 'segments', does not explain what is going on with the stretch shorten cycle.

The research in the 1990s by Marshall, Elliott et al recognized something was wrong with the kinetic chain concept for internal shoulder rotation (a defined shoulder joint motion where the shoulder joint does not necessarily move anywhere). They refer to ISR as "The missing link......"

Marshall & Elliott pointed this out several times in their early publications on internal shoulder rotation ("long axis rotation").

Long-axis rotation: The missing link in proximal-to-distal segmental sequencing

https://www.researchgate.net/profil...sequencing/links/004635393c2ce077ab000000.pdf
Its ironic that the most essential thing taught to players for decades is actually a hitch. Pete does have a very continuous motion.

At times i experiment with flowing through the stroke seamlessly as i can, and power and spin is achieved more easily, but its always difficult for me to do repeatedly.
 

GuyClinch

Legend
Most guys on this thread aren't half as good as this kid (in the video below) at serving - so leg drive is going to be somewhat lost on them IMHO. This always comes up around here. People have some kind of pushing motion with their serve and think 'leg drive' is what is holding them back. The real issue is not using a throwing motion.. And no IMHO the two are not tied together. In baseball you can use a crow hop and get more distance off your throw - or you can throw flat footed. Leg's help - but the throwing motion is the key..

That being said for my money the best in the world at teaching the leg drive - is Ric Macci.


Roddick style is the easiest to implement and makes the most logical sense IMHO.
 

Chingoo1255

Rookie
Update:

I've been serving with more of a platform stance and the leg bend has been minimal all this time. Most of the time the loading has not been on the rear leg at all. So I've been trying to go to pinpoint stance and I've found the pinpoint stance was different for me.
  1. Leg bend- it did not seem as awkward to bend legs lower
  2. Loading- it seems easier to load both legs evenly. With platform I was loading more unevenly
  3. Cartwheel- it seems more natural to cartwheel. With platform, I had more tendency to hit in a vertical plane as opposed to hitting with contact point behind my head
  4. Contact point in relation to the baseline- it was easier to toss into court and still make good contact. With platform I was not able to make consistent contact if I tossed more into court
  5. Timing- I had problems timing the racket drop in relation to the leg drive with pinpoint. The waiters tray was not pronounced like with platform.
  6. Serve and volley- I noticed that since the cartwheel is more natural, I'm transferring more weight into serve and the byproduct is I'm not going into court as diagonally as I was with pinpoint. I'm also ending into a more natural run into the court, so it should help me as I want to do more serve and volley plays instead of my current baseline play style.
I'm still trying to learn so if my observations are not consistent with your experiences please let me know. It might just be a fluke and a honeymoon; I'd hate it if I was totally wrong.

Thanks for reading!
 

GuyClinch

Legend
Pinpoint can work well - I never seen it well developed in a self-taught player though... Not saying it doesn't happen but almost all the guys I know who serve with it have had it taught to them.
 

shindemac

Hall of Fame
Update:

I've been serving with more of a platform stance and the leg bend has been minimal all this time. Most of the time the loading has not been on the rear leg at all. So I've been trying to go to pinpoint stance and I've found the pinpoint stance was different for me.
  1. Leg bend- it did not seem as awkward to bend legs lower
  2. Loading- it seems easier to load both legs evenly. With platform I was loading more unevenly
  3. Cartwheel- it seems more natural to cartwheel. With platform, I had more tendency to hit in a vertical plane as opposed to hitting with contact point behind my head
  4. Contact point in relation to the baseline- it was easier to toss into court and still make good contact. With platform I was not able to make consistent contact if I tossed more into court
  5. Timing- I had problems timing the racket drop in relation to the leg drive with pinpoint. The waiters tray was not pronounced like with platform.
  6. Serve and volley- I noticed that since the cartwheel is more natural, I'm transferring more weight into serve and the byproduct is I'm not going into court as diagonally as I was with pinpoint. I'm also ending into a more natural run into the court, so it should help me as I want to do more serve and volley plays instead of my current baseline play style.
I'm still trying to learn so if my observations are not consistent with your experiences please let me know. It might just be a fluke and a honeymoon; I'd hate it if I was totally wrong.

Thanks for reading!

Yes for the most part. I prefer something i call the narrow platform. It has less balance than the platform stance, but it gives as much power or more than the pinpoint. I switched to this stance after noticing on video that my back leg was not loading either (mainly due to weight shift to front leg). If your leg is dangling in the air, then pushing off will produce no power. That's why power always starts from the ground.

Yes, the rotation is a bit different with the 2 stances. One locks your hips in more and the other allows more free movement. Pinpoint provides more power (*simplified).
 
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