How to visualise the lag and whipping motion on the forehand and 2 handed backhand.

[S&V-not_dead_yet]

There is a larger point here. From what I read a lot of players on this Forum torture themselves with issues like this when they are consequences of more important underlying fundamentals. If your coiling is good and you have a reasonably compact backswing and you learn to swing to the forward extension point, issues about the wrist etc will tend to disappear.

It's a similar problem to watching high-level servers and noticing their back leg kicks up around waist-height and concluding that I need to work on my leg kick. No, I need to work on driving up into the serve so that the consequence is the leg kick. The leg kick is an effect of a good serve, not its cause.

 

[a12345]

This video offers a great breakdown of the slowing down of the body and torso before contact. At about 4.20 onwards it explains the end of the uncoiling of the shoulders.

For me, that the body stops rotating is not even in discussion, its obvious it happens. The kinetic chain works by firing one after another, it accelerates and decelerates passing energy from one part to the next.

By feeling and visualizing a rapid stopping of the turning of the body, it helps you to understand the difference in the timing of the kinetic chain between a classic and atp forehand.

In the classic forehand like Serenas, the shoulder ( i.e the last part of the kinetic chain in terms of the body) stops turning at roughly the same time as the arm and racket reaches contact point. Its all timed together.

In the ATP whippy forehand the shoulder stops turning before the arm gets to contact point i.e its gets there earlier, and the arm follows through after, towards contact.

So the kinetic chain on an ATP forehand is more explosive, turns faster, and finishes fraction earlier, causing the arm to lag and eventually "catchup" to whip the ball.

Hence thinking about stopping the body turn more abruptly should help you. This simple concept will help you to change the timing of your kinetic chain into a more whippy motion.

 

[ByeByePoly]

Another genious thread from the TTW armchair experts

Where is this abrupt and forced stop in the best forehands in the world then apart from rare ocassions?

Yo FireFl;y ... this armchair (actually recliner wide enough for a dog on both sides) noticed basically what @a12345 is saying back in Nov 2016.

https://tt.tennis-warehouse.com/ind...turn-acceleration-ends-around-contact.577827/

I actually think this observation/point is a key one in high level (let's say ATP strokes). ATP pros can't pass max momentum to the arm if they continue max torso/shoulder rotation through contact.

How does Fed's arm and hand (and your's on your FH btw) end up that far ahead of the shoulder line if the torso/shoulder rotation was screaming along at the same speed through contact? Jolly's coach tells him he wants his hand beating (going faster) than his body by contact. Again ... can't really pull that off if you are screaming torso/shoulder rotation through contact. I actually agree with @a12345 (and said it in that thread that I posted ... the torso/shoulder rotation will pick up again in follow through ... with the arm helping pull body around.

I have thought about this a lot since that first post above, and watched more videos (Some of Wawrinka's 1hbhs are a bit of a challenge to this theory) ... and I decided the key issue IS NOT if the torso/shoulder rotation pauses, or stops completely ... the real key issue is watching for efficient powerful hand off to the arm in the shoulder to arm relay. It can only be one of two things right? 1) torso/shoulder rotation pauses which helps send the arm and hand past shoulder liine .... OR 2) enough extra effort is added with the arm to make it go even faster than the accelerating torso rotation. Which one do you think it is? I can't think of a 3rd option why the hand beats the shoulder line to contact. (NOT EXACTLY true ... I think it's both ... a pause in shoulder rotation AND a BIG added effort with arm muscles before contact ... but that will derail the point of Mr @a12345 accurate OP and observation .... IMACO of course. In My Arm Chair Opinion.

So going back to what I think is the important kernel of truth in this .... not watching for pauses and stops, but watching for the arm being thrown forward powerfully by the torso/shoulders on both FH and BH ... I give you the Djoker from behind. Watch his right arm on FHs, and his left arm on 2hbhs ... those arms are being propelled as levers (not slung rope). There is magic in that arm being flipped (lever ... not rope) forward at the shoulder joint.

 

[ByeByePoly]

This video offers a great breakdown of the slowing down of the body and torso before contact. At about 4.20 onwards it explains the end of the uncoiling of the shoulders.

For me, that the body stops rotating is not even in discussion, its obvious it happens. The kinetic chain works by firing one after another, it accelerates and decelerates passing energy from one part to the next.

By feeling and visualizing a rapid stopping of the turning of the body, it helps you to understand the difference in the timing of the kinetic chain between a classic and atp forehand.

In the classic forehand like Serenas, the shoulder ( i.e the last part of the kinetic chain in terms of the body) stops turning at roughly the same time as the arm and racket reaches contact point. Its all timed together.

In the ATP whippy forehand the shoulder stops turning before the arm gets to contact point i.e its gets there earlier, and the arm follows through after, towards contact.

So the kinetic chain on an ATP forehand is more explosive, turns faster, and finishes fraction earlier, causing the arm to lag and eventually "catchup" to whip the ball.

Hence thinking about stopping the body turn more abruptly should help you. This simple concept will help you to change the timing of your kinetic chain into a more whippy motion.

I thought that was a great video. Who is that? @JohnYandell ... who was the instructor in that video?

 

[ByeByePoly]

@FiReFTW ... I think this torso/shoulder rotation “pause” is a “thing” in other sports also.

Check @00:13 below ... at contact shoulder turn has briefly paused, and the torso/shoulder rotation picks up again in follow through.

 

[JohnYandell]

Bye Bye,
No idea. I only watch my own videos...

 

[ByeByePoly]

Bye Bye,
No idea. I only watch my own videos...

hehehe

 

[sredna42]

You can't crack a whip around your body.
You can't skim a stone across the water around your body.

I can't do it though, my forehand is just total garbage, but the few times it has come together and worked (and I am not shanking balls from over rotating or opening the chest too soon or just pushing the ball with all arm) I have tried to imagine that throwing or whip cracking motion, but toward where I want to hit the ball. But still, even after all this practice, I just arm the ball or slap at it mostly

As my coach said to me, you see Federer do this, where he swings through and toward where the ball is going. All the energy is built up and dissipated/released into the ball at contact, the follow through after that should be just the aftermath or natural consequence of the swing.

 

[tennishabit]

Some people have a hard time getting that lag and snap/liquid whip motion on their strokes.

And the reason why in my opinion is that they are continuing through their strokes in the classic , smooth, WTA forehand style manner.

The key to feeling and getting the liquid whip happening is understanding that you need to stop turning , and you need to do it abruptly.

If you imagine sitting on a spinning disc rotating quickly and then I stop that disc, you go flying off it. Or imagine flicking a whip, the whippy effect comes from when you stop your hand and the whip follows through.

So in order to visualise how to get a liquid whip motion you need to turn your hips and body from facing the fence, to facing forwards, but then stop abruptly. Your arm will then be flung forwards as it catches up, and then finally the racket head will snap forwards from lag position to contact point. It should feel like the racket is doing quick bounce like an elastic band motion.

Now the same also applies to the 2 handed backhand. As you turn your hips and body quickly your arms and racket should almost feel "trapped" behind you, but as you stop turning abruptly at about 45 degrees facing forwards, your arms will catch up and the racket will snap forwards. Now the backhand will feel different from the forehand as youve got 2 hands on the racket but you should still feel that slingshot effect.

So the key to getting the whippy motion on both sides is to visualise not just how quickly you accelerate the turn of your body, but just as important how quickly you stop turning, in order to allow the lag and whip motion to take over.

If you follow through your body turn or do it in one smooth motion you will never get that lag snap effect, it has to be an abrupt turn and an abrupt stop to allow your arm and the racket to sling through like stopping the spinning disc.

any sudden/abrupt stop/takeoff ie rapid change of velocity consumes more energy than doing it in smooth/fluent way n also causing material fatigue ie injuries in this case.

actually it's very easy to find out: put it through a 'rigid durance test' by urself ie hit fh/bh as hard as you can on a practice wall 1000 shot every day for a few mths to see if it's plausible n ofc if it is, you'll be perfecting the shots along the way.

if not, u'll feel pain on ur wrist/forearm very soon n it might only needs a few days to take u down........n dat's what we always said 'walk the walk, talk the talk'.....

 

[FiReFTW]

Yo FireFl;y ... this armchair (actually recliner wide enough for a dog on both sides) noticed basically what @a12345 is saying back in Nov 2016.

https://tt.tennis-warehouse.com/ind...turn-acceleration-ends-around-contact.577827/

I actually think this observation/point is a key one in high level (let's say ATP strokes). ATP pros can't pass max momentum to the arm if they continue max torso/shoulder rotation through contact.

How does Fed's arm and hand (and your's on your FH btw) end up that far ahead of the shoulder line if the torso/shoulder rotation was screaming along at the same speed through contact? Jolly's coach tells him he wants his hand beating (going faster) than his body by contact. Again ... can't really pull that off if you are screaming torso/shoulder rotation through contact. I actually agree with @a12345 (and said it in that thread that I posted ... the torso/shoulder rotation will pick up again in follow through ... with the arm helping pull body around.

I have thought about this a lot since that first post above, and watched more videos (Some of Wawrinka's 1hbhs are a bit of a challenge to this theory) ... and I decided the key issue IS NOT if the torso/shoulder rotation pauses, or stops completely ... the real key issue is watching for efficient powerful hand off to the arm in the shoulder to arm relay. It can only be one of two things right? 1) torso/shoulder rotation pauses which helps send the arm and hand past shoulder liine .... OR 2) enough extra effort is added with the arm to make it go even faster than the accelerating torso rotation. Which one do you think it is? I can't think of a 3rd option why the hand beats the shoulder line to contact. (NOT EXACTLY true ... I think it's both ... a pause in shoulder rotation AND a BIG added effort with arm muscles before contact ... but that will derail the point of Mr @a12345 accurate OP and observation .... IMACO of course. In My Arm Chair Opinion.

So going back to what I think is the important kernel of truth in this .... not watching for pauses and stops, but watching for the arm being thrown forward powerfully by the torso/shoulders on both FH and BH ... I give you the Djoker from behind. Watch his right arm on FHs, and his left arm on 2hbhs ... those arms are being propelled as levers (not slung rope). There is magic in that arm being flipped (lever ... not rope) forward at the shoulder joint.

As i said before, theres a transfer from segment to segment like you say but its smooth not an abrupt and forceful and intentional stop.
When the segment before slows it passes the momentum to the next one which speeds up and as it slows it passes it to the next one etc but its not a forced and abrupt stop.
Imagine if you would want to stop every part of your kinetic chain from ur legs to hips to torso to shoulders intentionaly and forcefully and time it all, does that make any sense to you?

 

[Chas Tennis]

A few questions for advocates of the Kinetic Chain Concept:

1) What does the Kinetic Chain Concept have to say about the Stretch Shorten Cycle (SSC)? Never anything as far as I have seen.

"When the segment before slows it passes the momentum to the next one which speeds up and as it slows it passes it to the next one etc but its not a forced and abrupt stop.

2) What are segments? Examples?

3) 'Transferring speed from one segment to another' - How is speed 'transferred'?

4) How are stretched muscles involved?

5) Is there any way to create potential energy (in stretched muscles) for a 'segment' BEYOND the 'next segment' in a KC sequence? Say, skipping two, three or four segments ahead? In other words, say that the intermediate segments don't speed up much, are skipped, but somehow energy is still passed down the line of segments, how?

6) If so, is this segment skipping somehow a 'Momentumless' energy transfer using stretched muscles? In other words. does energy build up somehow well ahead of the KC sequence, ahead of the fastest segment?

7) Is segment skipping especially done during the tennis serve, somehow?

8) How come the early tennis researchers, around 2000, pointed out that there was a "missing link" in the tennis serve? Is the phrase "missing link" referring to the Kinetic Chain Concept?

9) Is the "missing link" in the title of the most important publication on the tennis serve referring to something that is wrong with the Kinetic Chain Concept?

10) Did the authors specifically discuss something being wrong with the Kinetic Chain? Even in the abstract?

Scan down the webpage to see the most important publication on the tennis serve.
https://www.researchgate.net/public...nk_in_proximal-to-distal_segmental_sequencing

The more advanced and scientific biomechanical approach to understanding tennis strokes uses the SSC as a very significant part of athletic motion. Once the biomechanical approach is in your bag of tools you start seeing SSCs in every tennis stroke and in walking.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577481/

 

[ByeByePoly]

As i said before, theres a transfer from segment to segment like you say but its smooth not an abrupt and forceful and intentional stop.
When the segment before slows it passes the momentum to the next one which speeds up and as it slows it passes it to the next one etc but its not a forced and abrupt stop.
Imagine if you would want to stop every part of your kinetic chain from ur legs to hips to torso to shoulders intentionaly and forcefully and time it all, does that make any sense to you?

We are all agreeing on the important part ... passing on momentum to the arm after shoulders hit end of range . According to Curiosity... the pros use the tuck of off arm to impede rotation ... which sounds pretty abrupt. How abrupt doesn’t matter to me ... I was very surprised at the shoulder turn pause when I first noticed it. On pro BHs ... 1hbh and. 2hbh ... the pause happens around chest pointing at left net post.

 

[Raul_SJ]

Fire,
But the forearm doesn't pronate. The hand arm and racket rotate as a unit from the shoulder. That's an independent variable.

Oh no. Just when I thought I finally understood pronation.

I had always viewed pronation as a forearm motion. Jim McClennan likes to describe pronation as "a forearm roll".
Ideally, ISR and pronation should happen together, as a unit...But pronation can happen with insufficent ISR, which is probably the common rec player error.

I think what you're saying is to forget about pronation on serve and forehand. Just think of ISR (rotate as a unit from the shoulder), and the pronation will naturally take care of itself?

Jim McLennan breaks down what he proposes is the key to the Pete Sampras serve – forearm pronation, or the “forearm roll” as he calls it.​

​

If you watch Pete’s serve in slow motion, the presence of strong forearm pronation is easy to see. Could this be how he generated so much power with such compact motion?​

​

https://racquetabuse.com/videos/learn/serve/forearm-pronation-on-the-serve/​

 

[Raul_SJ]

Is that a "snap?" Nope. The brilliant biomechanical researcher Brian Gordon measured what actually happens. Elite players are actually inhibiting the forward flex to create the right contact point and control the shot line. If the forearm muscles controlling the wrist were totally relaxed the racket head would come all the way around to neutral or even further due to the forces in the swing.

But hundreds and hundreds of high speed video examples from match play show the wrist is still laid back before, during and after contact. In fact sometimes more laid back after.

It makes sense that there is wrist forward flex and wrist is laid back (not past neutral) at contact.

https://imgur.com/FpbjejM

But what is the power contribution of that wrist forward flex on the forehand? Elliott says that on the serve, the wrist forward flex contributes ~30% of RHS.
It would appear that forward flex contribution is minimal on the forehand, maybe close to zero?

In terms of the Kinetic Chain, it is useful to think of the wrist forward flex as the end of the chain on the serve.
Likewise, it may be useful to think of the forearm roll (pronation) as the end of the chain on the forehand?

https://imgur.com/6vzxdJ1

 

[Raul_SJ]

A few questions for advocates of the Kinetic Chain Concept:

1) What does the Kinetic Chain Concept have to say about the Stretch Shorten Cycle (SSC)? Never anything as far as I have seen.

"When the segment before slows it passes the momentum to the next one which speeds up and as it slows it passes it to the next one etc but its not a forced and abrupt stop.

2) What are segments? Examples?

Not clear which segment constitutes the end of the Kinetic Chain on forehands. On the serve, it is the wrist (30% RHS contribution).
But on the forehand, there is apparently far less contribution from wrist flexion...

This link mentions SSC and Kinetic Chain, as it relates to the serve. Does anyone have similar link to forehand?

Technique: The Kinetic Chain​

​

The parts of the body act as a system of chain links, whereby the energy or force generated by one link (or part of the body) can be transferred successively to the next link. The link system in the service action, which starts from the ground, can be explained in the following way (Elliott and Saviano, 2001; Elliott & Kilderry, 1983):​

​

Leg drive​

Trunk rotation​

Upper arm elevation​

Forearm extension, upper arm internal rotation and forearm pronation​

Hand flexion​

​

The optimum coordination (timing) of these body segments and their movements will allow for the efficient transfer of energy and power up through the body, moving from one body segment to the next. Each movement in the sequence builds upon the previous motion and they all contribute to the generations of racket speed.​

​

This transfer of energy in sequential coordination is also enhanced by the stretch-shortening cycle of muscle action. The stretch-shortening cycle involves the active stretching (the muscle is activated but is elongated by another force) of a muscle in a countermovement immediately followed by a more forceful shortening of the muscle in the desired direction. In the forehand, for example, the chest and shoulder muscles are actively stretched (coaches often use the cue “loading” here) as the trunk rotates into the shot and the inertia of the arm and racket cause them to lag behind.​

The active stretch of the muscle stores energy in the elastic elements of muscle and associated tissues such as tendons, which is reused as the muscle begins to shorten. This sequence of muscular coordination tends to be chosen naturally by the brain, but sometimes this must be coached in players who develop pauses, that in turn lead to missed segment rotations or problems in sequencing segments.​

​

The most effective tennis strokes begin with leg drive generating ground reaction forces that can be transferred up the segments of the kinetic chain to the racket. Proper timing of the segments in the kinematic chain and stretch-shortening cycle muscle actions maximize the transfer of energy to generate the greatest racket speed.​

​

http://www.playerdevelopment.usta.c...t-Science/114390_Technique_The_Kinetic_Chain/​

 

[JohnYandell]

Raul,
Great question. The flex does (can) contribute to racket speed. That's what makes this issue so confusing and convoluted for so many. The forward flex is inhibited consciously but still exists and therefore adds racket speed and that's probably a significant contribution. But it's not something (good) players are trying to do...

 

[Chas Tennis]

There are links on the bottom of the imgur

Not clear which segment constitutes the end of the Kinetic Chain on forehands. On the serve, it is the wrist (30% RHS contribution).
But on the forehand, there is apparently far less contribution from wrist flexion...

The percentages that you mention are from Tennis and Biomechanics, B Elliott. Free online.

Those "contributions" presented are for racket head speeds in the forward direction resulting from each joint's rotary motion at the instant of impact. Nothing is said about the 'power' - a measurement at an instant of time. That's because maybe muscles or body parts are still accelerating the racket with some power adding energy and speed or maybe the body parts and racket are just cruising at high speed and no power is being applied at the instant of impact. See Newton's law of inertia. When you step on the gas your motor adds power, if not the car continues on because of its inertia.

Segments are the "sticks". For example, the Humerus bone or hand bones and surrounding body tissues.

"The principle of linked segments

The simplest model of the human body is a series of linked sticks (individual segments), joined at frictionless hinges (joints). Muscle force pulls on a segment, causing it to rotate faster or slower. The combined action of the muscle force at each joint and the resulting speed of each segment affects the speed at the distal end of the linked segments, such as a foot at the end of a leg or a hand at the end of an arm. (Think of any implement held in the hand as simply an extension of the distal segment.) The speed of the distal segment determines how much force it can apply, like a foot on the ground or a hand on a ball."
https://www.dummies.com/education/science/biophysics/biophysics-for-dummies-cheat-sheet/

This link mentions SSC and Kinetic Chain. Not clear if it is describing only the serve or the forehand as well.

Technique: The Kinetic Chain​

​

The parts of the body act as a system of chain links, whereby the energy or force generated by one link (or part of the body) can be transferred successively to the next link. The link system in the service action, which starts from the ground, can be explained in the following way (Elliott and Saviano, 2001; Elliott & Kilderry, 1983):​

​

Leg drive​

Trunk rotation​

Upper arm elevation​

Forearm extension, upper arm internal rotation and forearm pronation​

Hand flexion​

​

The optimum coordination (timing) of these body segments and their movements will allow for the efficient transfer of energy and power up through the body, moving from one body segment to the next. Each movement in the sequence builds upon the previous motion and they all contribute to the generations of racket speed.​

​

This transfer of energy in sequential coordination is also enhanced by the stretch-shortening cycle of muscle action. The stretch-shortening cycle involves the active stretching (the muscle is activated but is elongated by another force) of a muscle in a countermovement immediately followed by a more forceful shortening of the muscle in the desired direction. In the forehand, for example, the chest and shoulder muscles are actively stretched (coaches often use the cue “loading” here) as the trunk rotates into the shot and the inertia of the arm and racket cause them to lag behind.​

The active stretch of the muscle stores energy in the elastic elements of muscle and associated tissues such as tendons, which is reused as the muscle begins to shorten. This sequence of muscular coordination tends to be chosen naturally by the brain, but sometimes this must be coached in players who develop pauses, that in turn lead to missed segment rotations or problems in sequencing segments.​

​

The most effective tennis strokes begin with leg drive generating ground reaction forces that can be transferred up the segments of the kinetic chain to the racket. Proper timing of the segments in the kinematic chain and stretch-shortening cycle muscle actions maximize the transfer of energy to generate the greatest racket speed.​

​

http://www.playerdevelopment.usta.c...t-Science/114390_Technique_The_Kinetic_Chain/​

That is a very good find that I had not seen. But yes, I have heard B. Elliott use the term Kinetic Chain after he and Marshall wrote the publication on the serve in 2000.

Do the legs cause ESR and muscle stretching at the shoulder joint to be later used for ISR? But, I am just not seeing the "sequence" of segments getting 'faster and faster' as the segments transfer whatever up to the shoulder area. I believe that the segments picture muddles what is going on by emphasizing speeding up segments and hiding the SSC. I picked some questions to illustrate my view point. Will anybody apply the KC to answer them? Instead of the legs speeding up body segments, maybe a slow 2 x 4 (lumber) between the pelvis and shoulder mass would work as well to stretch the ISR muscles?

We need an expert in the Kinetic Chain Concept.

 

[Raul_SJ]

But yes, I have heard B. Elliott use the term Kinetic Chain after he and Marshall wrote the publication on the serve in 2000.

Elliott table shows the last link in the chain to be wrist forward flex, which contributes 30% of RHS. Does Elliott, or others, have a similar breakdown of the wrist flex contribution of RHS to the forehand?

This looks relevant but link is broken.

I recently found some references mostly by tennis biomechanics researcher Bruce Elliott and associates. I found them very interesting.


Instructional videos from a coach development workshop including 2 part Bruce Elliott & M. Reid video on the forehand. The first part is 56 minutes long and the first minutes are about foot work. Most stroke swing information starts at about 30 minutes.
http://www.tennis.com.au/coaches/resources/video

https://longislandtennismagazine.com/article386/biomechanics-tennis-fundamentals

Forehand​

​

The backswing, commencing with flexion of the lower legs and irrespective of style, is characterized by a loop, which has shown to increase racket speed (as opposed to the straight backswing which provides control), and a large rotation of shoulders and trunk.​

​

Forward swing to impact consists of trunk rotation initiating racket movement and is responsible for the forward movement of the hitting arm. Shoulder speed has been shown to contribute 25% of racket speed. The rotation of upper arm, forearm, and hand, account for the remaining 75% of racket speed at impact. Research indicates that the segmental contributions are influenced by grip type and ball level. Forward movement of the upper arm is a key feature of forehand mechanics, producing 30% of the racket speed. The hand plays an integral role in generating racket speed. The follow-through is across the line of the body and a recovery step brings the player into the ready position.​

​

 

[Dragy]

Raul,
Great question. The flex does (can) contribute to racket speed. That's what makes this issue so confusing and convoluted for so many. The forward flex is inhibited consciously but still exists and therefore adds racket speed and that's probably a significant contribution. But it's not something (good) players are trying to do...

There’s been a good wording for this: they allow it to happen in controlled manner.

 

[Raul_SJ]

There’s been a good wording for this: they allow it to happen in controlled manner.

In what scenario might the wrist be more laid back after contact? Inside-out forehand? Extreme topspin?

"But hundreds and hundreds of high speed video examples from match play show the wrist is still laid back before, during and after contact. In fact sometimes more laid back after. "

 

[tennishabit]

i just found an ad on 'gumtree.com.au' here from a french tennis coach.

https://www.gumtree.com.au/s-ad/ultimo/sports-partners/tennis-coach-hitting-partner/1082688638

his front page pic's showing how beautifully his rkt 'butting the ball' ie 'wrist lag'.............i reckon it should be printed as posters to put on the wall of every tennis clubs for all the rec-ers to admire n to inspire the kids...................

why the atp goats neol, rafa & roger don't have beautiful poster like that:?))))........their problems or photographers':?))).................

 

[Cashman]

I don't think I've ever had a coach use the words 'kinetic chain'. Do you guys really find your game improves by this sort of minute biomechanical analysis? I reckon it would just confuse things for me.

I also kind of feel like messing with your stroke production specifically to generate more power is going to do more harm than good to your average rec player's game.

Probably the best thing I have done for my own strokes was to read The Inner Game of Tennis.

 

[Dragy]

In what scenario might the wrist be more laid back after contact? Inside-out forehand? Extreme topspin?

"But hundreds and hundreds of high speed video examples from match play show the wrist is still laid back before, during and after contact. In fact sometimes more laid back after. "

Depends on what is “after”. More laid back “just after” will likely appear due to heavy collision (fast incoming ball, fast forward swing). The I/O racquet/arm configuration you refer to may facilitate such an event compared to more of “hooking” type of shot.

 

[Chas Tennis]

Elliott table shows the last link in the chain to be wrist forward flex, which contributes 30% of RHS. Does Elliott, or others, have a similar breakdown of the wrist flex contribution of RHS to the forehand?

https://longislandtennismagazine.com/article386/biomechanics-tennis-fundamentals

Forehand​

​

The backswing, commencing with flexion of the lower legs and irrespective of style, is characterized by a loop, which has shown to increase racket speed (as opposed to the straight backswing which provides control), and a large rotation of shoulders and trunk.​

​

Forward swing to impact consists of trunk rotation initiating racket movement and is responsible for the forward movement of the hitting arm. Shoulder speed has been shown to contribute 25% of racket speed. The rotation of upper arm, forearm, and hand, account for the remaining 75% of racket speed at impact. Research indicates that the segmental contributions are influenced by grip type and ball level. Forward movement of the upper arm is a key feature of forehand mechanics, producing 30% of the racket speed. The hand plays an integral role in generating racket speed. The follow-through is across the line of the body and a recovery step brings the player into the ready position.​

​

Biomechanics and Tennis __ Table 2 has forehand and serve data.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2577481/

 

[Raul_SJ]

The percentages that you mention are from Tennis and Biomechanics, B Elliott. Free online.

Those "contributions" presented are for racket head speeds in the forward direction resulting from each joint's rotary motion at the instant of impact.

How to reconcile Elliot's 30% contribution to RHS, from wrist forward flex, with Groppel's 10%?

 

[a12345]

Someone earlier mentioned Brian Gordon and his video below breaks down exactly whats happening.

At the beginning he talks about the 3 types of swing.

Type 1 the "classic" Serena type is where the body/shoulder/arm rotates in unison with each other in 1 continuous smooth kinetic chain.

The type 3 ATP swing is segmented where the body and arm move independently of one another. He even talks about the explosiveness of the kinetic chain and that its different in that it goes one after another, boom, boom, boom.

This shows how the kinetic chain and its timing, between classic and ATP forehands are different.

If you fast forward to 20 minutes, from there he then explains why the fast unit turn separated from the arm works - what you are doing is creating a stretch-shorten cycle.

He gives an example where he tries to pull his arm in using his bicep muscles. He then gets someone to resist his arm and then they pull away - his arm goes flying.

By rapidly rotating the body and leaving your arm lagging behind you are stretching the muscles in your arm and shoulders. As you release it your arm goes flying forwards.

A rapid body rotation is akin to stretching those muscles and the rapid stopping is akin to letting those muscles go.

So a rapid unit turn and stopping is the way to think about how your body should move in relation to your arm (not in unison, but separate), and the Brian Gordon video explains exactly why.

 

[Chas Tennis]

How to reconcile Elliot's 30% contribution to RHS, from wrist forward flex, with Groppel's 10%?

Tennis researchers did not understand that internal shoulder rotation (ISR) played such a significant part in the tennis serve until Elliott and Marshall published their 1995 measurements. I don't know how long that knowledge took to spread. By 2000 or so the ITF must have agreed and recognized this most important and amazing revelation. Disregard all analyses of the tennis serve before 1995 including the graph above.

There is also an old guideline for technical graphs. If the axes are not defined, or have units, in a way that makes sense and is clear, maybe the graph is no good. In this internet cut and paste information blizzard, look critically at the axes and see if they make sense. Tell me why the wrist has such a high Ground Reaction Force, the server is off the ground! ? (That is why the Elliott publicaions stand out, they make sense and use the scientific approach. When you study the material you understand it more and more, not wonder about the axes labels and generate questions.......)

Those that believe in the Kinetic Chain Concept should get a copy of the much referenced coaching book by J. Bunn, Scientific Principles of Coaching, 2nd ed, (1972). He presents some interesting original thinking. But I still don't buy the Kinetic Chain Concept.

Unfortunately, in the 1970s badminton researchers had discovered that ISR was very significant for the badminton smash and also recognized that ISR was very significant for the tennis serve. They communicated their results but tennis researchers did not pick it up. I wish that I had known what the badminton researchers were saying. In the 1970s, I was reading tennis books and practicing my Waiter's Tray serve - for the next 35 years!! Now I look at the strobe pictures in Vic Braden's 1978 book, Tennis for the Future, and see ISR.............

 

[Raul_SJ]

If you fast forward to 20 minutes, from there he then explains why the fast unit turn separated from the arm works - what you are doing is creating a stretch-shorten cycle.

.

What is meant by "separated from the arm"?

The body turns as a unit in a unit turn. Arm does not separate in the unit turn.

 

[Dragy]

Type 1 the "classic" Serena type is where the body/shoulder/arm rotates in unison with each other in 1 continuous smooth kinetic chain.

I think we should clearly distinguish “unison” from “kinetic chain”. The former supposed putting whole body effort together in one moment or period of time. The latter is ideally about passing the energy step after step. In theory. Practical application has it’s restrictions (body biology), and actual swings are all in the in-between range, closer to either end or another.

 

[Chas Tennis]

Accelerations and Forces

In your description of the Brian Gordon's video there is a very critical distinction - the difference between motion and motion with acceleration. Acceleration is more difficult to see than velocity but accelerations cause the forces.

F = mA
where F is force and A is acceleration, m is mass.

F does not = mV
where V is velocity.

The same as the forces you feel riding in a car as it accelerates or cruises. The same applies for rotary acceleration.

.........................
........... he then explains why the fast unit turn separated from the arm works - what you are doing is creating a stretch-shorten cycle. .............

The 'fast unit turn' does not stretch muscles, the accelerating uppermost body turn stretches muscles. For torque forces you need rotary acceleration not rotary velocity ('fast unit turn') .

........
By rapidly rotating the body and leaving your arm lagging behind you are stretching the muscles in your arm and shoulders. As you release it your arm goes flying forwards.............

The arm lags from the initial acceleration and not from "rapidly rotating the body". To fully release the upper arm and its stretched muscles you cease the acceleration. The uppermost body turn can continue.

........
A rapid body rotation is akin to stretching those muscles and the rapid stopping is akin to letting those muscles go.

As before, "rapid body rotation" does not stretch muscles. Accelerations stretch muscles. It is not necessary to stop the uppermost body's rotation for "letting those muscles go". It is only necessary to reduce or stop strong acceleration of the uppermost body turn in order to let stretched muscles accelerate the upper arm forward. Stopping or slowing the uppermost body turn are options.

........So a rapid unit turn and stopping is the way to think about how your body should move in relation to your arm (not in unison, but separate), and the Brian Gordon video explains exactly why.

Accelerations are the way to think about the forces that occur during the forehand.
There are options on when to apply accelerations to the turning of the uppermost body and when to slow or stop the turning. There are options on when to let the upper arm move relative to the uppermost body.

 

[S&V-not_dead_yet]

I don't think I've ever had a coach use the words 'kinetic chain'. Do you guys really find your game improves by this sort of minute biomechanical analysis? I reckon it would just confuse things for me.

I also kind of feel like messing with your stroke production specifically to generate more power is going to do more harm than good to your average rec player's game.

Probably the best thing I have done for my own strokes was to read The Inner Game of Tennis.

I think it depends on the student, the skill level, the ability and willingness to learn, etc.

I see people who turn to the side and then swing completely with their arm; their body does not rotate even one degree. They are not only leaving a lot of power on the table but stressing their arm to boot. Introducing the KC concept in a slow progression would benefit them immensely, IMO.

TIGoT addresses how to think about your game; the KC addresses how to actually execute. They are complementary.

 

[a12345]

In your description of the Brian Gordon's video there is a very critical distinction - the difference between motion and motion with acceleration. Acceleration is more difficult to see than velocity.

F = mA
where F is force and A is acceleration, m is mass.

F does not = mV
where V is velocity.

The same as the forces you feel riding in a car as it accelerates or cruises. The same applies for rotary acceleration.




The 'fast unit turn' does not stretch muscles, the accelerating uppermost body turn stretches muscles. For torque forces you need rotary acceleration not rotary velocity ('fast unit turn') .



The arm lags from the initial acceleration and not from "rapidly rotating the body". To fully release the upper arm and its stretched muscles you cease the acceleration. The uppermost body turn can continue.



As before, "rapid body rotation" does not stretch muscles. Accelerations stretch muscles. It is not necessary to stop the uppermost body's rotation for "letting those muscles go". It is only necessary to reduce or stop strong acceleration of the uppermost body turn in order to let stretched muscles accelerate the upper arm forward. Stopping or slowing the uppermost body turn are options.



Accelerations are the way to think about the forces that occur during the forehand.
There are options on when to apply accelerations to the turning of the uppermost body and when to slow or stop the turning. There are options on when to let the upper arm move relative to the uppermost body.

When I say "unit turn" it should say "body turn". My mistake. Basically what ive been saying throughout this thread.

as for

"To fully release the upper arm and its stretched muscles you cease the acceleration. The uppermost body turn can continue. "

The upper most body does not continue, it stops to release the arm and it is the arm that gets released forwards.

If you continue to rotate the shoulders you are still stretching the muscles and you havent released them.

 

[a12345]

What is meant by "separated from the arm"?

The body turns as a unit in a unit turn. Arm does not separate in the unit turn.

My mistake here, it shouldnt say unit turn it should just say body turn. I mean the uncoiling rather than the coiling.

 

[Raul_SJ]

I think it depends on the student, the skill level, the ability and willingness to learn, etc.

I see people who turn to the side and then swing completely with their arm; their body does not rotate even one degree. They are not only leaving a lot of power on the table but stressing their arm to boot. Introducing the KC concept in a slow progression would benefit them immensely, IMO.

TIGoT addresses how to think about your game; the KC addresses how to actually execute. They are complementary.

A good coach certainly needs to understand the fundamentals of the kinetic chain to diagnose issues. He may or may not transmit that directly to the student. He will likely use some other cues to convey the message.

I did get better results on serve when I learned on this forum to time the leg extension with the racquet drop to facilitate deeper drop (greater ESR). The coaches at the clinics I attended did not really mention this...

Also, I do get a better result on the serve when I feel the stretch in the chest muscles, although I am not clear on the mechanism of why this chest stretch helps and how it fits into the Kinetic Chain.

 

[a12345]

I think we should clearly distinguish “unison” from “kinetic chain”. The former supposed putting whole body effort together in one moment or period of time. The latter is ideally about passing the energy step after step. In theory. Practical application has it’s restrictions (body biology), and actual swings are all in the in-between range, closer to either end or another.

The passing of the energy step by step is different though, as he mentions in the video he says the timing is different.

If we consider the kinetic chain as legs -hips - torso - upper body - arm - wrist or however you want to break it down, the important difference between the different type of forehand is the timing in between the upperbody - arm.

It is segmented in a type 3 forehand whereas it is more fixed in a type 1.

In a type 1 the kinetic chain between upperbody - arm is more connected and happens together, he calls this a "unit swing" where its more trunk dominated and the arm just goes along for the ride in a relatively fixed position. This is a more "all around the world" motion.

In a type 3 forehand the arm and the body is segmented. The body turns quickly and the arm gets left behind stretching the muscles. As the body turn stops (last part being the shoulders) the muscles get released and throw the arm forwards.

 

[Raul_SJ]

Depends on how you define snap. There is no active pushing of the wrist. However if your wrist is loose it will release from a fully cocked back position during the swing to a slightly more forward position at contact point. And it will do this simply because the forward motion has stopped and the arm and racket is catching up.

.

Is Serena considered lag and snap? Or is she in that Brian Gordon category of torso and arm move more or less together?

 

[a12345]

Is Serena considered lag and snap? Or is she in that Brian Gordon category of torso and arm move more or less together?

Shes more in the torso and arm together camp. Any independent arm movement is very mild. Type 1, Type 2, in between maybe?

She meets the ball pretty much in sync when you see the point at which she stops turning and the racket touches the ball.

 

[FiReFTW]

I guess according to ttw experts djokovic has a wta forehand since its almost exactly the same as serena when it comes to body arm and swing style, lol

 

[FiReFTW]

Chas is right that its the acceleration and a loose wrist that produces the lag and stretch shorten cycle not having to use the body before the arm.
If not then the atp players wouldnt be able to produce this lag when on the run and using only arm, and yet they do when they sometimes "slap" the ball like that.

 

[JohnYandell]

Raul,
No particular scenario that I could tell. Just shows that there isn't forward intentional flex--the wrist is laid back enough the the impact increases the lay back slightly.

 

[Kobble]

Chas is right that its the acceleration and a loose wrist that produces the lag and stretch shorten cycle not having to use the body before the arm.
If not then the atp players wouldnt be able to produce this lag when on the run and using only arm, and yet they do when they sometimes "slap" the ball like that.

You aren't taking into consideration that running gives the whole body momentum that can be leveraged.

 

[Kobble]

A few questions for advocates of the Kinetic Chain Concept:

1) What does the Kinetic Chain Concept have to say about the Stretch Shorten Cycle (SSC)? Never anything as far as I have seen.

"When the segment before slows it passes the momentum to the next one which speeds up and as it slows it passes it to the next one etc but its not a forced and abrupt stop.

The stretch shortening cycle is a way to transfer kinetic energy (1/2m x v^2) into elastic potential energy. It makes it easier to load up that energy to save it for a later time frame and release it.

As for passing on momentum from one link to another, I don’t think that is entirely transferred. This would be like saying that if a person was sitting on a merry go round as the merry go round had them moving at 20 m/s, and the merry go round just stopped, that the person would fly off at greater than 20 m/s. that is not consistent with observed objects rotating around an axis. They are known to fly off at the exact tangential velocity they had before the string was cut. The momentum tied up in the weight and moment of inertia of the merry go round is transferred to the breaking system used to slow (stop it). Now, if someone wants to say, “Ya, the breaking system. The extension on the next limb is the breaking system, and that is where the momentum goes.” No. That is where some of the momentum goes, not all. The inner part will slow because some of that momentum will be tied up in the new addition to its moment of inertia. It is likely that, by most evidence, kinetic energy is the currency for transferring speed in segments, not momentum. If you look at all Langrangian equations, they use kinetic energy terms to describe double pendulum motion. Other more common evidence for momentum of one link not being fully transferred to the next link is the summation of speeds description for the kinetic chain.

 

[Dragy]

The stretch shortening cycle is a way to transfer kinetic energy (1/2m x v^2) into elastic potential energy. It makes it easier to load up that energy to save it for a later time frame and release it.

As for passing on momentum from one link to another, I don’t think that is entirely transferred. This would be like saying that if a person was sitting on a merry go round as the merry go round had them moving at 20 m/s, and the merry go round just stopped, that the person would fly off at greater than 20 m/s. that is not consistent with observed objects rotating around an axis. They are known to fly off at the exact tangential velocity they had before the string was cut. The momentum tied up in the weight and moment of inertia of the merry go round is transferred to the breaking system used to slow (stop it). Now, if someone wants to say, “Ya, the breaking system. The extension on the next limb is the breaking system, and that is where the momentum goes.” No. That is where some of the momentum goes, not all. The inner part will slow because some of that momentum will be tied up in the new addition to its moment of inertia. It is likely that, by most evidence, kinetic energy is the currency for transferring speed in segments, not momentum. If you look at all Langrangian equations, they use kinetic energy terms to describe double pendulum motion. Other more common evidence for momentum of one link not being fully transferred to the next link is the summation of speeds description for the kinetic chain.

If a person was sitting on a merry go round with it’s hips bound to the seat, a sudden stop would cause the upper body fall, where the head would initially move faster than 20m/s. That’s what happens with hand being the end of the arm, and with racquet head coming from deep lag. The former is additionally enhanced with SSC shorten phase, the latter may or may not be deliberately restricted as JY pointed out.

 

[Dragy]

I guess according to ttw experts djokovic has a wta forehand since its almost exactly the same as serena when it comes to body arm and swing style, lol

As a player, especially the one relying on your coach, you may not need to get into all techniques details. But as a poster here giving out opinions you'd maybe find it useful to get understanding of key things. There's crucial difference between Serena and Novak swings in those videos.

Starting from here Serena both rotates her torso and flexes her chest muscles swinging her arm to come in front of torso plane by contact. She never reaches such a position:

Nole, just as most ATP players on most of their FH drives, doesn't let his arm take off from this "trailing" position until chest facing roughly the target, and contact is about to happen. And the reason for this techniques is not to get the fancy lag, but to ensure strong and consistent link and rapidly transfer big power produced by torso rotation to arm.

 

[Kobble]

If a person was sitting on a merry go round with it’s hips bound to the seat, a sudden stop would cause the upper body fall, where the head would initially move faster than 20m/s. That’s what happens with hand being the end of the arm, and with racquet head coming from deep lag. The former is additionally enhanced with SSC shorten phase, the latter may or may not be deliberately restricted as JY pointed out.

Do you have any physical experiments that show the velocity gain on video?

For those wondering, that still isn't transferring extra momentum from the merry go round. Just leveraging the momentum the person possesses as a separate system, and leveraging that in an angular fashion to finagle more kinetic energy out of it.

 

[Dragy]

Do you have any physical experiments that show the velocity gain on video?

For those wondering, that still isn't transferring extra momentum from the merry go round. Just leveraging the momentum the person possesses as a separate system, and leveraging that in an angular fashion to finagle more kinetic energy out of it.

Kinetic chain is a concept, not a physical law/proved theory/etc., something you could apply like a formula. I find SSC mechanics to be the most pure demonstration of the concept, where actual storage of energy takes place. In other cases it could be describing actual decrease in losses due to counteraction of power sources, and lifting limitations, couldn’t it? FH sequential, segmented mechanics is actually a great example: when a player uses best timing instead of trying to use all power sources (leg drive and core muscles to move forward and rotate torso, chest and shoulder muscles to swing arm forward), he achieves better outcome. Same for serve, first loading the shoulder and setting proper body structure, then firing ISR to accelerate the racquet, then pivoting it on top of the motion to direct achieved RHS.

 

[FiReFTW]

As a player, especially the one relying on your coach, you may not need to get into all techniques details. But as a poster here giving out opinions you'd maybe find it useful to get understanding of key things. There's crucial difference between Serena and Novak swings in those videos.

Starting from here Serena both rotates her torso and flexes her chest muscles swinging her arm to come in front of torso plane by contact. She never reaches such a position:

Nole, just as most ATP players on most of their FH drives, doesn't let his arm take off from this "trailing" position until chest facing roughly the target, and contact is about to happen. And the reason for this techniques is not to get the fancy lag, but to ensure strong and consistent link and rapidly transfer big power produced by torso rotation to arm.

Your talking like your right and im wrong and I should accept that your right and get to understand these key things as you say.
But why would I find it useful to get understanding of these key things when my opinion is that these key things are wrong?

You showed two pictures of Serena and Novak at two COMPLETELY different phases of the stroke to prove some point I don't understand even.

If you look at the same time and frames then apart from a few differences like novak having his left arm parallel to baseline and serena having it into the court etc.... there doesn't appear to be ANY significant difference in any part of the body or swing or stroke between the two forehands:

 

[Cashman]

A good coach certainly needs to understand the fundamentals of the kinetic chain to diagnose issues. He may or may not transmit that directly to the student. He will likely use some other cues to convey the message.

This is really my point. I'm not sure how helpful it is to load up with a lot of biomechanical minutiae when you're essentially trying to imprint a behaviour.

 

[a12345]

I guess according to ttw experts djokovic has a wta forehand since its almost exactly the same as serena when it comes to body arm and swing style, lol

The angles are slightly varied between the 2 videos this one below is a would represent the difference better at a flatter angle.

Concentrate on his logo on the shirt. At what point does this pretty much stop moving, or slow down to a minimal movement?

I would say at 14 seconds and 31 seconds for the first 2 shots.

In particular with the second shot, pause it at 31 seconds and see how far away he is from the ball after finishing his body turn. Hes done a fast turn , stopped, and the arm is catching up/being released. The body and arm is segmented.

In your Serena video look at the Nike Logo, it kind of continues turning as shes hitting the ball, the Nike logo is turning much more in unison with her arm.

 

[a12345]

With Simona Halep, the Adidas logo just about turns in unison with her arm. It faces forward right before the racket hits the ball.