Kinetic Chain - What do we know on the serve?

[Chas Tennis]

In 2014, how well do we understand the kinetic chain in a general way and, in particular, for the tennis serve ?

Here is a much displayed graph used to represent the kinetic chain for the tennis serve.

This graph originated in a publication from 1992, as shown, so there must be more recent and revised displays. Anyone have others?

I have not read the original publication but this well know display has some problems. It may have been intended only as a conceptual display of the kinetic chain and for identifying the sequence of important motions, and for that, it is excellent. But the one axis is labeled "Ground reaction force". It does not seem to make sense to have an axis labeled Ground reaction force with high values after the feet have left the ground. What does a large Ground reaction force mean for the wrist when the feet are not touching the ground? Can anyone explain? This graph may be causing confusion.

The graph is also labeled "Ball Speed from a Tennis Serve" but how that is shown on the graph is not clear to me.

Here is a more recent discussion of the kinetic chain.
http://www.aspetar.com/journal/viewarticle.aspx?id=6#.UvolELRNtKA

What do we have to display the kinetic chain that is better?

------------------------------------------------------
Updates - other links on the kinetic chain

See - The 4000 Watt Tennis Player (2009)
http://www.itftennis.com/media/127877/127877.pdf

Power and the Tennis Serve (ITF)
http://en.coaching.itftennis.com/media/114010/114010.pdf

ITF Coaching Presentation with similar kinetic chain sequences but just used conceptually. (2007)
http://en.coaching.itftennis.com/media/113862/113862.pdf

USTA - The Relationship Between Stroke Mechanics and Injuries in Tennis (2006) (including the above graph)
http://assets.usta.com/assets/1/USTA_Import/USTA/dps/doc_437_391.pdf

USTA - TENNIS TECHNIQUE AND INJURY PREVENTION (2004)
http://assets.usta.com/assets/1/USTA_Import/USTA/dps/doc_437_102.pdf

USTA - Technique: The Kinetic Chain
http://www.usta.com/Improve-Your-Game/Sport-Science/114390_Technique_The_Kinetic_Chain/

ITF - Advanced stroke techniques: The serve ITF Coaches Education Programme Level 2 Coaching Course
Amazingly this 2007 presentation leaves out internal shoulder rotation!
http://en.coaching.itftennis.com/media/113902/113902.pdf

ITF - Biomechanics and stroke production: implications for the tennis coach ITF Coaches Education Programme (2007)
http://www.uclm.es/profesorado/xaguado/ASIGNATURAS/BTD/4-Apuntes/Tema 2/IO_24964_original.pdf

USTA - Biomechanics of the Serve, page 5.
http://assets.usta.com/assets/1/USTA_Import/USTA/dps/doc_437_1400.pdf

By the Laws of Newton.......Tennis Anyone???
http://biomechanics101.wordpress.com/2013/07/09/tennis-anyone/

Science and Racket Sports III: The Proceedings of the Eighth International Table Tennis Federation Sports Science Congress and The Third World Congress of Science and Racket Sports (2003)
Chapter 15, An overview of the application of biomechanics to racket sports., A. Lees, See especially section 2 - Motion analysis studies - kinematics
Best & most complete history I've found of biomechanics research bearing on the history of understanding the tennis serve.
http://books.google.com/books?hl=en...Jrm477QCVoLDMGrZ2G2CA0fXQ#v=onepage&q&f=false

Technique Effect on Upper Limb Loading on Serve, B. Elliott et al, (technical)
http://biomechanics.stanford.edu/me337/projects/elliot03.pdf

Internal Rotation of the Upper-Arm Segment During a Stretch-Shorten Cycle Movement, B. Elliott et al, (technical)
http://www.americankinesiology.org/AcuCustom/Sitename/Documents/DocumentItem/2393.pdf

Science and Major Racket Sports: A Review, A. Lees, see Biomechanics, pages 717 & 718.
http://www.tenisdemesa.com.co/documentos/ciencia.pdf

High Tech Tennis, 2nd Ed, (1992), J. Groppel, low cost, great reference for tennis stroke biomechanics views in the 1990s.

2nd reference shown on graph, Kibler, probably the source of the graph above. Abstract only.
http://www.ncbi.nlm.nih.gov/pubmed/7799762

 

[sureshs]

The graph is also labeled "Ball Speed from a Tennis Serve" but how that is shown on the graph is not clear to me.

I think it was meant to say: "Relative contribution to Ball Speed from a Tennis Serve"

 

[Chas Tennis]

Do you mean the %'s.

If so, what do the %s pertain to, energy, power, ball velocity, other? For example, the wrist adds "10%" of the energy to the ball or adds 10% to the velocity. ?

Maybe they mean that the energy in each step upward is less? ?

In any case, the graph could be very useful but the meaning of the things presented is not spelled out.

Later research by Elliott et al about 1995 identified specific joint motions and evaluated the contribution of each joint motion to the final racket head speed for the serve. That is where the '40% contribution from internal shoulder rotation' comes from. These joint motions can be seen and measured in high speed videos (unlike power & energy). IRS joint motion contributes 40% of the final racket head speed. (Also, the powerful ISR might also be causing the wrist joint flexion and its big contribution.)

See Table 2
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577481/

 

[sureshs]

Do you mean the %'s.

If so, what do the %s pertain to, energy, power, ball velocity, other? For example, the wrist adds "10%" of the energy to the ball or adds 10% to the velocity. ?

Maybe they mean that the energy in each step upward is less? ?

Yes


Yes

 

[scotus]

The best wheelchair players are said to serve as fast as 110 mph. So the whole leg and hip components on the graph are outrageously exaggerated.

Also, jumping doesn't seem to add a whole lot of power to the serve. Wawrinka, who routinely serves 130 mph, doesn't get off the ground. Taylor Dent, who can serve as fast as Roddick, teaches on Tennis Academy that jumping up does not add much power to the serve.

 

[sureshs]

The best wheelchair players are said to serve as fast as 110 mph. So the whole leg and hip components on the graph are outrageously exaggerated.

That is the problem when you take only the best.

"Without the benefit of a propulsive leg action, wheelchair players developed lower peak absolute (∼32 m/s) and horizontal (∼28 m/s) pre‐impact racquet velocities than able‐bodied players (∼42 m/s, ∼38 m/s)."

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2465259/

 

[LeeD]

Main thing, citing ONE study means very little.
Yes, wheechair players can serve over 100.
That study is plain wrong, but I won't venture to say I know what is correct.

 

[Ash_Smith]

I believe that Elliot & Reid's latest studies indicate that leg drive contributes around 12% of total racquet velocity and that ISR contributes around 30%?

And yes, the best wheelies can hit around over 100, the lad that I recently took to the Junior Worlds hit a serve at 103mph in the final, however serving with less spin required to hit that quick is too big a risk in most cases, so most wheelchair first serves would be equivalent to a typical ATP second serve in terms of ball speed.

 

[LeeD]

Leg drive, 10%, seems real to me.
I can't run. Haven't for 7 years. I can serve around 100.

 

[sureshs]

How much does the leg drive contribute to the contribution of the higher parts in addition to its absolute contribution, if you know what I mean.

 

[LeeD]

Would it depend if you classify leg drive as part of torso twist? TTwist can be part of the leg drive, because it surely happens less for wheelchair tennis players.

 

[sureshs]

I think that would fall under Trunk and Back

 

[TCF]

Not sure if this adds any information. But we have players sometimes serve from their knees, then using their entire bodies. If my memory is correct a typical 95 mph server hits something like 60 mph from their knees. Maybe we will try some various serve limitations later and measure with the radar gun.

 

[sureshs]

Wheelchair players may have learned to use their upper body more efficiently than able-bodied players, so it might be misleading to infer relative contributions to serve speed from them.

 

[Ash_Smith]

^^^If you are comparing elite wheelchair players to recreational players then yes, that's probably true. If you are comparing elite wheelies to elite non-disabled players then there should be little to no difference in upper body mechanics.

 

[sureshs]

Can wheelchair players get some sort of lift by pressing down on the chair with their upper body, like able-bodied players can get by pressing down on the ground with their feet?

 

[Ash_Smith]

^^^ depends on their level of disability, but not in a way that I can see making a significant contribution

 

[Chas Tennis]

I believe that Elliot & Reid's latest studies indicate that leg drive contributes around 12% of total racquet velocity and that ISR contributes around 30%?

And yes, the best wheelies can hit around over 100, the lad that I recently took to the Junior Worlds hit a serve at 103mph in the final, however serving with less spin required to hit that quick is too big a risk in most cases, so most wheelchair first serves would be equivalent to a typical ATP second serve in terms of ball speed.

Do you have the reference for the latest Elliott & Reid study? Guess that it is not available free on line.

In the few publications that I've seen, they usually list the angular velocities of the most important joints in the last few hundredths of a second before impact and use that for contributions to velocity. That method makes the contribution from the legs difficult to factor in since the legs did their thing earlier in the service motion for the most part. ? They must have changed their old method for the leg contribution. ?

 

[boramiNYC]

Chas, I think your reasoning is sound. It should be difficult to isolate segmental contribution for many reasons.

When you are coordinated enough you can disable some joints and feel the difference but the chain is so interconnected it doesn't simply work sequentially either IMO.

And there are many ways to use the chain to ultimately hit good serves so specific numbers may not be very meaningful.

 

[KineticChain]

here i am

_____________

 

[rufus_smith]

Maybe this will help a little:
http://www.actakin.com/PDFS/BR0202/SVEE/04 CL 06 ND.pdf

The model consists of 8 criteria:
A. GRF (Ground Reaction Force) - starts after
significantly flexing the knees (summation of
forces towards racket)
B. Disturbed balance, extended arm position
in a way that allows hips moving forward
C. Shoulders begin to rotate aside from the
net position
D. Internal rotation of the upper arm and
forearm pronation
E. Hand flexion
F. Body lands inside the baseline with trunk
flexed forward
G. Left and right hip follow OCG trajectory
H. OCG continues to move forward until
gaining balance for new a

I've recall seeing a video decades ago where a scientist got a pro tennis server to stand a large metal plate device when he served. He was able to measure the peak amount of downward force on the metal plate during the serve. The force was much more than the weight of the player and was incredibly high.

 

[Topspin Shot]

^^^Here's the video. http://www.youtube.com/watch?v=42STJgl2K4E

 

[SystemicAnomaly]

The best wheelchair players are said to serve as fast as 110 mph. So the whole leg and hip components on the graph are outrageously exaggerated.

Also, jumping doesn't seem to add a whole lot of power to the serve. Wawrinka, who routinely serves 130 mph, doesn't get off the ground. Taylor Dent, who can serve as fast as Roddick, teaches on Tennis Academy that jumping up does not add much power to the serve.

The wheelchair players that I have watched (there are a couple of world class players in my area), use their tossing hand to stabilize the chair after the toss. For the right-handed server, puts their left hand on the left wheel to steady the chair.

There is still a ground reaction force (GRF) between the wheels and the court. It is possible that this force is still transmitted to the core and the upper body of the wheelchair player. Notice also that the wheelchair players with the biggest serves tend to have fairly massive arms and a well-developed core & torso.

Sure, many able-bodied servers can serve primarily with the shoulder/arm. However, this is not advisable for a full set or match. Doing so, would put undue stress on the shoulder and arm over time. Better to involve the legs (which includes the strongest muscles in the body), hips and other links of the chain to minimize stress to the shoulder/arm. It also makes for a more efficient service action. While the shoulder/arm generates a portion of the power supplied to the racket, they also transfer a portion developed by the lower body.

Wawrinka, Dent and others still use a fair amount of leg drive even if they do not jump on the serve. This leg drive is transferred to the hips and upper links of the chain. Leaving the ground (jumping) might be an indication that the legs are providing a slightly greater contribution to the overall kinetic link system. One advantage of jumping is that it gives that server a higher contact point (and a better angle to hit into the service box).

 

[boramiNYC]

here i am

_____________

I think Chas is asking you a question.

 

[SystemicAnomaly]

here i am

_____________

So what do you know on the serve?

 

[KineticChain]

i know it has to go in the box part and you get 2

 

[spacediver]

to build on what systemic said, I think this discussion would be improved if we acknowledged the distinction between active torque and passive torque.

It is theoretically possible for the wrist to provide 90% contribution to racquet head speed, yet provide 0% of the active torque.

With this in mind, we can start asking sharper and more meaningful questions.

a good place to start would be to use google scholar to do a search for the keywords tennis serve in the last 3-4 years.

 

[Chas Tennis]

...........................................................
a good place to start would be to use google scholar to do a search for the keywords tennis serve in the last 3-4 years.

What is "google scholar"? Is it any different than a google search?


Update -
Wow, this is hugh!! Thanks!
http://scholar.google.com/intl/en-US/scholar/about.html

http://scholar.google.com/schhp?hl=en

For a particular library - not sure how this works yet.
http://www.youtube.com/watch?v=WsTPZItV3No

 

[Ash_Smith]

The wheelchair players that I have watched (there are a couple of world class players in my area), use their tossing hand to stabilize the chair after the toss. For the right-handed server, puts their left hand on the left wheel to steady the chair.

There is still a ground reaction force (GRF) between the wheels and the court. It is possible that this force is still transmitted to the core and the upper body of the wheelchair player. Notice also that the wheelchair players with the biggest serves tend to have fairly massive arms and a well-developed core & torso.

Those that take the wheel are likely para's who need the stability from holding the wheel as they cannot balance themselves de to inability to recruit core muscles. Lumbar or lower breaks or other disabilities/conditions should not take the wheel, but curl the tossing arm into the torso (as a non-disabled player would) to increase rotation speed.

Just for info

 

[Chas Tennis]

to build on what systemic said, I think this discussion would be improved if we acknowledged the distinction between active torque and passive torque.

It is theoretically possible for the wrist to provide 90% contribution to racquet head speed, yet provide 0% of the active torque.

With this in mind, we can start asking sharper and more meaningful questions.

a good place to start would be to use google scholar to do a search for the keywords tennis serve in the last 3-4 years.

There are some more recent updates in the OP.

Especially, USTA - Technique: The Kinetic Chain

Check the brief comments on the "Stretch Shortening Cycle".

 

[hawk eye]

One of the most common errors which messes up the kinetic chain is being too early with the racket drop from the trophy pose, in relation to the leg movement. You want to drop your racket when you start to straighten your legs from the kneebend, until then you keep it up. You see so many- even higher level- players with their racket postion already lower before the straightening of the legs. This is diminishing the effect of the leg drive significantly, because that way you never come in the optimal power position, which means the legs are fully stretched and you racket head is at its lowest level (position 4 in the sequence below)

 

[spacediver]

There are some more recent updates in the OP.

Especially, USTA - Technique: The Kinetic Chain

Check the brief comments on the "Stretch Shortening Cycle".

thanks Chas, will check em out.

 

[sureshs]

i know it has to go in the box part and you get 2

Not true. You can get as many as needed if it goes into the box and also touches the net on the way.

 

[GuyClinch]

One of the most common errors which messes up the kinetic chain is being too early with the racket drop from the trophy pose, in relation to the leg movement. You want to drop your racket when you start to straighten your legs from the kneebend, until then you keep it up. You see so many- even higher level- players with their racket postion already lower before the straightening of the legs. This is diminishing the effect of the leg drive significantly, because that way you never come in the optimal power position, which means the legs are fully stretched and you racket head is at its lowest level (position 4 in the sequence below)

True. But lower level players usually aren't getting a proper chest angle, shoulder rotation or the cartwheeling action either..

You can serve big with just a little leg bend..like the guys did in the old days. I think adding in a lot of legs is very difficult and should be the last step YMMV.

Its tough because its easy to see someone isn't using their legs but if they just try to throw in some squatting it doesn't really work..

 

[Raul_SJ]

I've recall seeing a video decades ago where a scientist got a pro tennis server to stand a large metal plate device when he served. He was able to measure the peak amount of downward force on the metal plate during the serve. The force was much more than the weight of the player and was incredibly high.

Does this ground reaction force apply to the forehand as well? One needs to
exert a huge downward force(greater than body weight) on the ground by significantly bending the knees?

OTOH, According to Jeff Salzenstein, knee bend is not all that important in generating power on the forehand. Jeff places very little emphasis on knee bend with his forehand instructional videos.

 

[LeeD]

I've seen huge servers who barely bent their knees, and barely got off the ground.
I've seen weak servers who jump almost a foot off the ground.
If you have the quick racket acceleration and know when to allow the head to come thru at the correct time, you will have a big serve.
If timing issues or swingspeed issues linger, your serve will be weak no matter what kind of leg push you provide.

 

[rufus_smith]

Does this ground reaction force apply to the forehand as well? One needs to
exert a huge downward force(greater than body weight) on the ground by significantly bending the knees?

OTOH, According to Jeff Salzenstein, knee bend is not all that important in generating power on the forehand. Jeff places very little emphasis on knee bend with his forehand instructional videos.

Good question. I've not seen anybody test that, but I would guess the groundstrokes produce extra ground force too. I think you need only a little knee bend to do it, if any. It seems like we can exert pressure on the ground just by tensing the quadriceps and calf and ankle and feet. It would be like you were squishing a bug under your foot or trying to stay upright on a bumpy bus or train.

 

[SystemicAnomaly]

... I've recall seeing a video decades ago where a scientist got a pro tennis server to stand a large metal plate device when he served. He was able to measure the peak amount of downward force on the metal plate during the serve. The force was much more than the weight of the player and was incredibly high.

Was that Jack Groppel or Bruce Elliot? Did not see the video but I do recall reading about pressure plate studies back in the 90s (or was it the late 80s?). I do not recall any numbers but the study showed that GRF for a platform serve and a pinpoint serve were nearly the same -- slightly greater for pinpoint than platform for the server(s) tested.

 

[boramiNYC]

It seems like we can exert pressure on the ground just by tensing the quadriceps and calf and ankle and feet. It would be like you were squishing a bug under your foot or trying to stay upright on a bumpy bus or train.

No, that's not true. Just tensing muscles won't increase the pressure. There needs too be vertical weight shift to increase the pressure more than the weight.

But tensing muscles well can increase the stability significantly even without the vertical weight shift. This controlled tensing is critical to the quality of movements and posture.

 

[Chas Tennis]

Was that Jack Groppel or Bruce Elliot? Did not see the video but I do recall reading about pressure plate studies back in the 90s (or was it the late 80s?). I do not recall any numbers but the study showed that GRF for a platform serve and a pinpoint serve were nearly the same -- slightly greater for pinpoint than platform for the server(s) tested.

From an earlier reply

^^^Here's the video. http://www.youtube.com/watch?v=42STJgl2K4E

 

[Chas Tennis]

The Kinetic Chain is the transfer of.......... what? .......


---------------------------------------------------------------
After you wrestle with this for a while read from the OP -

------------Links Fixed -----------------

USTA - Technique: The Kinetic Chain
http://www.usta.com/Improve-Your-Game/Sport-Science/114390_Technique_The_Kinetic_Chain/

and

By the Laws of Newton.......Tennis Anyone???
http://biomechanics101.wordpress.com/2013/07/09/tennis-anyone/

 

[hawk eye]

True. But lower level players usually aren't getting a proper chest angle, shoulder rotation or the cartwheeling action either..

You can serve big with just a little leg bend..like the guys did in the old days. I think adding in a lot of legs is very difficult and should be the last step YMMV.

Its tough because its easy to see someone isn't using their legs but if they just try to throw in some squatting it doesn't really work..

Yes rec players are often not getting those either and that should be adressed as well.

But what you see is that lots of people first lower the racket head in the trophy postion before they really drop it, and that reduces racket head speed. So this habit is bad because it's impairing the effectiviness of the kinetic chain, but also because it slows down racket head speed as such. So even if a player has no or very limited leg drive, he should prevent this from happening.

 

[Fintft]

I've seen huge servers who barely bent their knees, and barely got off the ground.
I've seen weak servers who jump almost a foot off the ground.
If you have the quick racket acceleration and know when to allow the head to come thru at the correct time, you will have a big serve.
If timing issues or swingspeed issues linger, your serve will be weak no matter what kind of leg push you provide.

I agree, based on my own, limited experience.

Cheers!

 

[SystemicAnomaly]

^ Players who jump a foot off the ground and yet get a weak serve have a broken link in the kinetic chain (no kinetic transfer) or have a serious flaw in one or more of the links after the legs.

From an earlier reply

Thanks. Missed that video link. That video must have been from the late 70s or early 80s. However, that was not the study that I had read that measured both platform & pinpoint serve styles with a pressure plate.

The Kinetic Chain is the transfer of.......... what? .......

---------------------------------------------------------------
After you wrestle with this for a while read from the OP -

USTA - Technique: The Kinetic Chain
http://www.usta.com/Improve-Your-Gam...Kinetic_Chain/

and

By the Laws of Newton.......Tennis Anyone???
http://biomechanics101.wordpress.com...tennis-anyone/

Speaking of broken links, yours do not appear to work. Are these the correct links?

http://www.usta.com/Improve-Your-Game/Sport-Science/114390_Technique_The_Kinetic_Chain/
http://biomechanics101.wordpress.com/2013/07/09/tennis-anyone/

 

[Chas Tennis]

Those are the right links. Fixed the bad links above. Thanks.

 

[Lukhas]

Funny no one seems to have mentioned that video analysis of Roddick's serve so far, comparing his serve to a 5-stage rocket. Not that it would matter in the big picture. The thread is still very interesting to read.

 

[Chas Tennis]

Funny no one seems to have mentioned that video analysis of Roddick's serve so far, comparing his serve to a 5-stage rocket. Not that it would matter in the big picture. The thread is still very interesting to read.

I've have not seen it in a while and have lost track of it. Do you have the link?

This one?
http://www.youtube.com/watch?v=pLf_MJXzBVg

 

[Lukhas]

^Yeah, this one. But I'm not sure if it's very relevant here anyway given the mass of information available. I'm reading a bit of it; I'm not sure it's going to help me on court, but it's still very interesting to see how it works.

 

[LeeD]

Nice to know how Roddick does it.
Not applicable in life, because NO other person can do it like Roddick.
The one or two who tried, guys like Monfils, do it like Monfils.

 

[Lukhas]

^Hip speed and coil is important in every service motion. It's not a Roddick thing: he "just" does it better, faster and deeper than others. Look at how much Petros turns away from the ball, his back almost facing the net, and how much he turns his lower body before contact. It's a big picture so I just put a link.
http://news.tennis365.net/lesson/img/pro_gif/sampras_serve_03_0312.jpg

And that's IMO something that differentiate most women from men when it comes to serving. The ability to use the hips, use the trunk and a proper coil to generate power instead of compensating with the shoulder and arm.
http://www.youtube.com/watch?v=v8q2cBx19ec

EDIT: That reminds me... I have the full "Nick Bollettieri's Sonic Serve" on my HDD. You can only find short extracts on YouTube. Even if there aren't precise numbers given, there's a big emphasis on the coil at the set to launch position (=trophy pose), the similarities between a baseball pitch and the serve, or the engagement of the hips inside the baseline.