The Serve: Twist Versus Forward Rotation

[doctorhl]

I can’t get a player to admit that if vibrations are felt in the knee,, hip, shoulder, elbow joints when learning a new service motion, then there is a sequencing problem. Most students want to blame the credibility of the new technique or just be satisfied with “muscling through” their old method which is inefficient or prone to injury. Their thought process??.....“ this technique destroys my timing”. But, this video series will be a game changer for those are willing to improve.

[seano]

Stotty -

Great idea. Love it.

SeanO

[stotty]

I think the best way to establish a better understanding Brian's video series is to put it into practice. We need some guinea pigs. What interests me most is the business of applying Brian's science. Hopefully in the coming weeks I can isolate a few kids in my club with leg drive problems and start a video workshop in this thread. Anyone will be welcome to chip in with some words of wisdom. Hopefully it will bring 10splayer out of hibernation, too.

Watch this space....

[BrianGordon]

Thanks don_budge - look forward to reading this in the coming days.

[don_budge]

Brian...the preceding is something that I posted some years ago. I use the rollercoaster and the track theory in teaching the serve. It's interesting to merge your theories with my paradigm.

[don_budge]

The Three Rules for Injury Free Serving...Perfect Motion...Perfect Motion...Perfect Motion

This is honestly one of my favorite posts of all time. I had a lot of fun trying to express this idea. The Gravitational Pull on the Racquet Head. It's a car on a RollerCoaster ride that stays on track.

Love Rollercoaster...The Ohio Players 1975

https://www.youtube.com/watch?v=aBkVV9xxCHE

The Roller Coaster of Love...Part 1

Then I wrote this in April for Phil's "frustrating" thread...I deleted this one as well. Stupid me, I didn't realize that this was somehow related to Rod Cross's physics lesson on...what is it he is talking about anyways? I remember talking to my college roommate and doubles partner and backcourt mate on the basketball court, many years ago, 1076 I believe it was...he was a Chemical Engineering major, I said to him..."you know Jim, a tennis match is really one big physics problem and equation, I wonder if you could take an entire tennis match and express it as an equation in terms of force, vectors, with specific quantification." He looked up at me from his studies and said, "That's an interesting thought." I never did follow up on my thought. He went on studying and I went out to practice.


Roller Coaster of Love...remember that tune?


Phil...I have been studying your video over the last couple of weeks and gleaned everything I can from it. The one view has its limitations and the still sequence of your serve adds some insight as well. The only sure way to do this thing is in person...care to fly over to Sweden for a couple of lessons. Just kidding.


The service motion is a bit complex and it involves quite a bit of motion from all of the different parts of the body...so we try to simplify things by creating a model we can relate it to in simple terms. The model that I use is the “berg och dallbana” which translates literally into English from Swedish as the “mountain and valley course”...but it means “roller coaster”. A roller coaster is an amusement park ride that is perfectly designed using the law of gravity. The design is so perfect that the ride feels that it is wildly out of control and traveling at incredible speed...but is so amazingly in control that the owners of such rides are betting everything they have that the ride will not spin out of control and kill a bunch of innocent people on a Saturday afternoon. This is the safe and secure principle we shall attempt to modify your backswing to in order to get you going forward into the “hit” with perfect and effortless energy. We are going to be using gravity as our main source of energy...to create a perfect, yet simple motion...a roller coaster of a serve.


Here’s the thing, Phil...about the set up and backswing. This is a real challenge without having you in front of me to study for a while. To set you up to begin your motion I would like you to create a line directly at your target with the toes of your two feet which are approximately shoulder width apart. Imagine this line going forwards towards your target and all the way back of you to the fence. This line will serve as our “track” for the backswing. I would like to see you bent slightly at the waist so that your arm can “swing” from your shoulder without your body getting in the way. Finally, I would like you to line your racquet up to your target as well, on the same line as the line that your feet created. Point your racquet at the target and hold it about waist high supported by your left hand. Weight distributed from between 60/40 to 70/30 from the front foot to the back. Great...now we have you lined up, and taking aim.

Here we go...hold on to your hat! One thing that we must clarify before we go into any kind of explanation about the motion is the pressure of your grip. Sam Snead referred to the grip on his golf club as holding it with only so much pressure as you would hold a live bird. We only hold on with our hand tight enough to not let go of the racquet. We maintain only enough pressure in the entire arm, forearm and wrist to swing the arm and racquet back into position in one piece without disturbing the exact position that it is in at the setup position. We must eliminate all sources of tension and resistance when we are attempting to use pure gravity to dictate our motion. From this relaxed and confident position at setup we need only to release the racquet with our left hand that is supporting it, and allow the weight of the racquet head to merely fall upon the line of the track all the way back to the fence until it reaches a position at the top of the hill. From the starting position, the roller coaster car begins its decent down the first hill until it reaches the bottom where it will begin its assent slowly up the second hill all the way to the top. Remember the track is along the line that we created with our feet towards our target and it extends all the way back. Keep the racquet on this track. By allowing gravity to dictate the direction and speed of our backswing we will create the position back in our swing where the laws of gravity make the most sense and the least number of things can go wrong. In fact nothing can go wrong...just like the roller coaster. By dropping the racquet head and allowing the weight of it to travel smoothly in front of you and only using the energy of your weight transferring to the back foot by slowly turning your shoulders and allowing your arm to freely swing back into position, we create a position where the racquet will naturally drop behind us at free fall speed into what you are referring to the “pro drop” position.

Now this is where things get a bit interesting...and exciting. Thinking about this point of the motion where the racquet makes a loop starting at free fall speed, behind our backs and how it relates to a roller coaster, we can imagine where the cars of the ride go into a loop and the riders are actually upside down on the track with only gravity to keep them glued to the track. This is where the riders of the roller coaster are screaming at the top of their lungs and their faces are contorted with the g-force that is plastering the tissue of their faces to their skulls. It’s in the loop, baby! This is where the drive of the legs, the turning back of the shoulders and the thrusting or throwing motion of the racquet combine to exponentially create an incredible amount of speed with very little effort. You can imagine that the line a piece of pencil would draw if it was attached to the tip of the racquet...this is your track for the roller coaster of your serve.

The backswing is where I observe the source of your issues. It looks to me that if we can get you into position you can make the move forward if you can maintain a loose grip on the racquet and the relaxation in your arm to create a whip like sensation. (insert post #32 at this point for the action of the wrist)


Just one more thing...it looks to me in frame #3 you have tossed the ball right out of the picture and in frame #4 it is returning to earth. I think your toss is a bit high...which would lead us to the next lesson, how and where to toss the ball.


A description of the Pancho Gonzales serve…

The Gonzales service is a natural action that epitomizes grace, power, control and placement. The top players sigh when they see the smooth, easy action. There is no trace of a hitch and no unnecessary movements. I have never seen a serve so beautifully executed. The toss is no higher than it has to be and it is timed so that he is fully stretched when he hits it. The backswing is continuous and the motion of the backswing blends into the hit and continues into the follow-through without a pause..

Like you...I am a huge admirer of the Gonzales serve...and he obviously knew his "metaphysics".

[BrianGordon]

don_budge - yes, I can see the analogy and yes altered states was probably the last movie I saw (or caddy shack). The platform is my preferred stance due to the simplicity as you mention. Also it is more productive in generating the forward angular momentum because the positioning of the feet optimizes the direction of the ground forces required for that momentum.

The forward angular momentum requires the net force from the ground to pass just behind the body center of mass so the role of the feet is to direct that force appropriately. This is primarily a upward oriented force (linear) so twisting the feet to produce a twisting torque from the ground would be much less important compared to the golf swing the instructor describes.

The screw driver analogy would be closer to some ground stroke techniques but that is another (very long story). Thanks for the the though provoking questions.

[don_budge]

The Golfer in the Woodpile...

Thanks don_budge. You could be right about missing my calling but tennis was in my blood since the age of 5. Golf was also as my mother was an accomplished amateur player with a legit chance to be pro - she unfortunately (probably for her) made the choice to have me and start a family. Her brother also was very good in college and on the minor league circuit and was a scratch player well into his sixties - so I was raised around golf.

Me, I played a lot but was never able to apply my mechanics apparently as about a 10 handicap was the peak of my career. I agree about the symmetry of being accomplished, in practice or theory, between the two sports. I appreciate the higher level of importance placed on mechanics in golf - often mystified why many tennis players tend to be resistant.

Aha...thanks Brian. Thanks for this. It helps to connect the dots. The three little...dots.

I never cease to amaze my self with little things. Impressions. Clues. Call them what you will. But while tennis might have been in your blood...golf is definitely in your DNA. I love the connection to golf and a 10 handicap is nothing to sneeze at. Just FYI...I took my first golf lesson on my fortieth birthday and had the handicap down to a 2 when I took the job here in Sweden teaching tennis that eventually led me to this website. Connecting dots Brother.

But back to the ability to amaze myself with myself. Some posts back I referred to you as a "fascinating individual" and now you have shed further light on the subject. I suspected a golfer in the woodpile so to speak. It makes sense. It sort of makes me wonder...but never mind. This chromosomal connection to golf may actually predispose you for a love of tennis. More of my theories. Have you ever seen "Altered States"? But never mind. You recall my comment about "tennis being golf on the run" and "I learned more about teaching tennis from playing, learning and teaching golf then I ever did from playing tennis". Just indulge me a bit if you would Sir.

I have frequently made the observation that the tennis serve is somehow related to a golf swing only it is sort of upside down. With the tennis serve we "tee it up" at a point over our heads as high as we can reach. In a golf swing the ball is lying on the ground or teed up slightly above the ground. So in order to keep this simple and directly or indirectly related to this particular video about twist rotational force versus forward rotation...let's talk about the feet.

If you recall I asked you about which stance that you preferred and I was most relieved to hear that your response was the platform. This is the perfect place to begin. Why would you prefer the platform stance for starters (the point in which to initiate the discussion)? The second part of my inquiry is a follow up to something that I asked you but you missed in the myriad of layers of my often rambling inquiries...what about the role of the feet? Theoretically all motion must begin from the ground up so what kind of pressure or rotation are the feet making in the service motion. Just to remind you...I saw on a video this summer when I was trying to resurrect my golf swing from the dust bin...one instructor compared the action of the feet to applying pressure on the ground as if you are tightening a screw into the ground on the backswing and then doing the reverse on the forwards motion.

I think that tennis instructor should take golf lessons in order to better understand biomechanics on a feeling basis...qualitative versus quantitative. Somehow it might just be simpler as the motion is produced from a static position but that doesn't seem to make it any easier. It is still so difficult to get your ass in position...if you know what I mean. Biomechanically speaking.

Thinking a bit more on the subject as I am typing...it's interesting to try and imagine your explanation of rotational forces in the golf swing. The twist versus the forwards.

[BrianGordon]

Thanks don_budge. You could be right about missing my calling but tennis was in my blood since the age of 5. Golf was also as my mother was an accomplished amateur player with a legit chance to be pro - she unfortunately (probably for her) made the choice to have me and start a family. Her brother also was very good in college and on the minor league circuit and was a scratch player well into his sixties - so I was raised around golf.

Me, I played a lot but was never able to apply my mechanics apparently as about a 10 handicap was the peak of my career. I agree about the symmetry of being accomplished, in practice or theory, between the two sports. I appreciate the higher level of importance placed on mechanics in golf - often mystified why many tennis players tend to be resistant.

[don_budge]

Thanks for this don_budge. To me it looks better in black and white than watching an old guy gimping around.

Never thought much about the Dr. thing. I guess on some level it validates the 20 years of "higher education" to understand human motion. On the other hand it probably makes many wonder who would be crazy enough to spend that kind of effort to understand how to hit a little yellow ball. At any rate, please call me Brian - no-one I know calls me Dr. and most call me Bri - my players shorten it to B.

I didn't read your piece but will if you tell me where to find it. Afraid golf mechanics is outside my realm although some in my academic labs studied it. From that I got bits and pieces. I will say the best qualitative description I've seen of mechanics in any sport is the golf book: Search for the perfect swing by Cochran and Stobbs. Are you familiar with it?

I'm with you on the platform stance. Thanks for your kind words and time, BG

I think that transcript is a good complement to the video. I thought you were looking pretty distinguished and sounding very credible. A nice performance. I'll check out the golf book. You may have missed your calling. It seems to me that what you are doing for tennis is what any number of fellows are doing for golf. I really feel that generally speaking there is a much better understanding biomechanically speaking in golf than there is in tennis. There aren't too many doing the sophisticated analysis that you have laid out from your research.

I sometimes cryptically make the comment that I have learned more about teaching tennis from playing, studying and teaching golf than I did from playing tennis. I describe tennis as golf on the run. The nice thing about golf is that you don't have to succumb to the years as early as you do in tennis. There isn't any real hurry to get to the ball. Which is another story in itself. It would be interesting to see if your understanding of biomechanics would help you to learn the golf swing.

[BrianGordon]

Thanks for this don_budge. To me it looks better in black and white than watching an old guy gimping around.

Never thought much about the Dr. thing. I guess on some level it validates the 20 years of "higher education" to understand human motion. On the other hand it probably makes many wonder who would be crazy enough to spend that kind of effort to understand how to hit a little yellow ball. At any rate, please call me Brian - no-one I know calls me Dr. and most call me Bri - my players shorten it to B.

I didn't read your piece but will if you tell me where to find it. Afraid golf mechanics is outside my realm although some in my academic labs studied it. From that I got bits and pieces. I will say the best qualitative description I've seen of mechanics in any sport is the golf book: Search for the perfect swing by Cochran and Stobbs. Are you familiar with it?

I'm with you on the platform stance. Thanks for your kind words and time, BG

[don_budge]

Interesting video Brian. I can call you Brian...can't I? Do you know in Sweden that people never refer to doctors and Dr. So and So? In this society they are really on guard that nobody thinks that they are better anyone else. Just a little cultural anomaly.

Brian...did you ever read my little story of the roller coaster serve? I'm not certain if I drew it to your attention or not. I transcribed your video in the two posts above. It's a great exercise for me. I must have heard the video at least five times in total by going back and forth...listening and typing. I think it really enhanced my understanding of what you were driving at.

Question for you Sir...do you know anything about golf and the golf swing? I think that you would find that motion to be ultimately fascinating too. I have compared it to an upside down tennis serve. In a tennis serve we attempt to tee the ball up where we are going to hit it instead of teeing it on the ground. Golf swing analysis seems to be light years ahead of tennis swing analysis. You seem to have a corner on the market when it comes to breaking down the motion to its bio-mechanical foundation.

I find this concept of "ground force" rather curious. I notice one of your models using a platform stance which a advocate almost exclusively. The less moving parts, the less that can possibly go wrong. In such a complex motion it seems wise to make it a simple as possible. I saw on a golf video the instructor was recommending to use the feet like they were turning a screw into the ground on the backswing and doing the reverse on the forward swing.

Very interesting video and it was fun to transcribe it. Studying your paradigm and at the same time studying you. Nice delivery! Nice serve!

[don_budge]

Twist Rotation Versus Forward Rotation…Dr. Brian Gordon (cont.)


Transcribed from video below (cont.)

https://www.tennisplayer.net/members/biomechanics/brian_gordon/serve_twist_versus_forward/

I will also say that there is a requirement for a slight twist rotation from the ground reaction so in the ground reaction again I am trying to generate a forward rotation of the body. I do need a minimal input from the back leg to get the hip initially started around. That will help as I acquire twist rotation from the forward angular momentum later in the swing.

When I talk about these things people inevitably say to me…”oh, but there are examples in the fairly recent history of players that do seem to still be rotated like this”. So in other words they appear to still be driving a significant amount of their kinetic fuel from generating a twist rotation from the ground. But closer inspection of those players shows that they actually use this forward rotation or somersault based swing mechanics and they are only essentially starting from a more turned position in order to change the axis of rotation from parallel to the baseline to a little bit skewed. The reason that one would want to do that is that it makes the rotation generation a little bit more diagonal compared to the baseline which is a very useful thing in generating spin rotation on the ball, particularly on kick rotation.

So…for servers, Pete Sampras being a notable example, that generated both pace abut also significant amount of rotation on the serve, it would be beneficial to instead of having a purely forward rotation axis to have one that is diagonally skewed to diagonalize the transition from the torso rotation to the arm and having the arm segments coming out not so much forward as they would on a flat power serve in the forward oriented one to a more diagonal path which would facilitate their ability to generate a significant amount of rotation on top of the (power/path ?).

This series is really a follow up to a series that I wrote on John’s site tennisplayer.net in the mid 2000’s. It was a very detailed and difficult to understand and read series of five or six articles really getting into the base mechanics of the stroke. This is a follow up in that it is designed to be a little bit more applied. In other words, I am describing things rather than writing them in brutal detail. So…hopefully that will enhance understanding of what I wrote a little over a decade ago. Most of which still stands…actually all of it still stands. There’s been some additions to it.

[don_budge]

Twist Rotation Versus Forward Rotation…Dr. Brian Gordon


Transcribed from the video below:

https://www.tennisplayer.net/members/biomechanics/brian_gordon/serve_twist_versus_forward/

Having played a wide variety of sports it quickly became apparent to me that tennis was by fare the most complex and difficult to master. So I can remember as a young man…actually a boy growing up I spent countless hours thinking about how this stroke should work, experimenting with the best way to do things which is a little bit unusual for a child of that age. But if I was to be completely honest I would say that most of the concepts that are in my current teaching methodology have been present in my recent research were actually hatched before I was twelve years old.

So I guess it was inevitable at some point that I would further my knowledge and course of study become involved in the study of biomechanics which is the physics of human motion. Because of my interest in tennis strokes as a young man and trying to become a better player that was obviously what I chose to work on. All of the strokes are of interest to me but of particular interest was the serve because it struck me as being one of the most complicated and interesting motions in all of sports.

So as my education progressed and I became able to use quantitative methods of measurement and take a much deeper look at stroke mechanics in the serve in particular several things appeared to emerge. The information that came out through my study starting in essentially 1995 through my Masters and PhD work and up to the present in my applied work on the tennis court, showed that the certain mechanics that I was seeing are much different than the ones that I was taught when I was a young man.

In particular what I was taught when I was young and to a great extent this is still prevalent in tennis today is that the serve is fundamentally a twist based motion. Which is to say that the forces that are exerted on the ground in the preparation of the body should be such that the body is rotated very far away from parallel to the baseline…er, perpendicular to the baseline and that the forces that are exerted on the ground are used to generate a twisting rotation of the torso. I can remember as young as eight years old when I was told this, thinking this makes absolutely no sense.

Why would a motion in which I am fundamentally developing racquet speed in a vertical direction be predicated by a twisting rotation of the torso? So, in other words, I am being asked to twist my body this way and yet produce racquet head acceleration this way. From a very young age that made absolutely no sense to me. What was interesting is that as my knowledge increased and more data come about, I found out that the more better servers in more recent times do not in fact use a twist rotation of the body directly to impact racquet speed development.

To be clear, when I talk about a twist rotation, I am talking about rotation of the body around an axis that is vertical. So my hips, my shoulders, everything is twisting this direction about this axis which means that I am using ground forces, pushing on the ground interacting with the ground to generate a twisting rotation. But what the research has shown is that the way that the serve is developed is not so much through this twist rotation but actually through a forward rotation of the body. A forward rotation of the body, which I refer to a lot as a somersault rotation, is around an axis that is parallel to the baseline. If we consider that axis passing through the centre of my body, I would be generating rotation starting from the ground and then through transferring the rotations around this axis. A forward axis making my body rotate essentially forward which is in stark contrast to a twisting rotation.

So all of the actions that I use starting with the ground, pushing on the ground are used to develop a forward rotation and the subsequent body rotations are used to transfer that rotation or what in biomechanics we call angular momentum through the torso and into the hitting arm. This is a far different paradigm that I learned as a boy and a paradigm that is still fairly prevalent in tennis. So in a twisting rotation I would start rotating away from the baseline, I would use the ground to generate a twist rotation and I was actually taught to step through with the back foot. Again that makes no sense if the goal is to generate vertical racquet acceleration.

More recent serving and what my serve evolved to without coaching, by the way, is that rather than doing that you generate forces from the ground to generate a forward rotation you would leave the ground and land with the front foot with the body actually tumbling forward. So in other words I am developing all of this rotation and using that as kinetic fuel for the motions of the arm approaching impact in the upwards swing. I don’t mean to imply that the twist is not actually important. What I am saying and what I will discuss later is that the twist rotation of the body does not necessarily need to be generated by exerting effort in pushing against the ground. The twist rotation, particularly of the upper torso, can be derived from the forward rotation generated from the ground by placing the body in a very particular orientation in the air. That seems to be what most of the high level servers do to this day.

[BrianGordon]

jmtennis - great questions - thanks.

There is of course some risk associated with trunk rotation but it is my experience it is no greater than the risk associated with playing tennis in general, or any sport for that matter. Most of back injuries seem to occur through a simultaneous combination of twisting and non-twisting torso rotations. The most dangerous is twist combined with extension often seen in preparation for the backswing.

I've been fortunate not to have any back injuries in my many years of coaching. I'd like to believe this is due to good mechanics but maybe I'm just lucky. The lateral trunk rotation occurs before the twisting - they do not occur with significance at the same time (lateral - backswing; twist - upward swing). Further, the extent of lateral rotation is built in over time starting at about 5 degrees and progressing to about 25 degrees. Even 25 degrees is pretty moderate and fortunately the most required to transfer forward angular momentum.

Pronation of the forearm is insignificant - the forearm acts as transmission for the internal shoulder rotation but is not independently pronated, in fact the opposite, research has indicated it is supinated slightly on average. The wrist goes to a neutral position from muscular contraction of the wrist flexors - this is not a motion dependent event - internal shoulder rotation tends to drive the wrist into extension, not flexion.