some thoughts on the biomechanics of full serve motion vs. isolated motions

spacediver

Hall of Fame
One thing I've thought about is how practicing small chunks of the service motion relates to actual serving. For example, I've spent a lot of time with myself (and a bit of time with friends), working on the latter portion of the upward swing. First I teach them what internal shoulder rotation is, and how it affects the racquet head path during the upswing. Then I explain elbow flexion, and elbow pronation (though I emphasize that internal shoulder rotation is far more important than elbow pronation).

Now when someone practices this portion of the serve in isolation, the pattern of independent torque vs. motion dependent torque is likely different from when you are using a full service motion. In the isolated motion, you arguably have to consciously activate the internal rotators and triceps to a larger degree, as they cannot derive their torque from the forward angular momentum channeled up through the torso. On the other hand, when one is practicing these motions, it's usually at a much slower pace than during a real serve, so perhaps this balances things out in terms of intensity of muscle activation.

Either way, I still think it's incredibly useful to go through these motions as it still provides kinesthetic feedback that is relevant to the real service motion. My knowledge of muscle neurophysiology is limited, but I think that there are receptors in the muscle tissue that fire regardless of whether the joint is actively or passively rotated. In particular, the temporal pattern of this kinesthetic feedback may generalize to full serving mechanics and can thus reinforce good serving mechanics.

Another related limitation of isolated practice is that you don't experience the same muscle loading patterns (stretch shortening cycle) as you would when you have momentum being passed up from the torso. However, in my experience as a developing athlete, learning to harness muscle loading is something that comes quite naturally. So I don't think that practicing isolated movements will interfere with learning to use muscle loading as one progresses to fuller mechanics.

Which leads me to the last point... progressions. I think a geat progression model is to start at the final portion of the motion (latter part of upswing), and then progressively add antecedent elements in cumulative fashion. One good heuristic may be to wait until the student is able to achieve a great whip motion until progressing to the next step. By a great whip motion, I mean utilizing the available kinetic chain to produce good racquet head speed (safety considerations may have to apply here, as attempting to generate high racquet head speed with isolated motions may put dangerous stress on relatively weak joints such as the shoulder, elbow and wrist). By employing this approach, the student has a series of well defined goals and can learn to discover good mechanics. As they progress, they can learn to keep their arm loose and relaxed, as they let the legs and torso (and hopefully "imprinted" patterns of muscle activation) guide the motion.

I'm going to test this out on friends, as well as myself. I'm thinking about teaching myself to serve with my left arm (I'm extremely right hand dominant), as I think this will be a good test of these ideas, and may also give me some useful teaching insights.
 

NLBwell

Legend
In simpler terminology, I'll teach the serve starting with holding the racket up in the air, then the toss, then hitting the ball with just the wrist (I don't expect them to get it over the net), elbow and wrist, shoulder and elbow and wrist, then start including the body. The toss point does move a bit when the body starts moving.
It works really well, getting beginners to hit serves correctly quickly and can work out kinks in more advanced players serves.
 

SystemicAnomaly

Bionic Poster
I taught myself to serve with my non-dominant (right) arm in a similar fashion. I would practice a fuller motion with shadow serves (no ball) but used a progressive approach, as you've suggested, when learning to serve with an actual ball.
 
Which leads me to the last point... progressions. I think a geat progression model is to start at the final portion of the motion (latter part of upswing), and then progressively add antecedent elements in cumulative fashion. One good heuristic may be to wait until the student is able to achieve a great whip motion until progressing to the next step. By a great whip motion, I mean utilizing the available kinetic chain to produce good racquet head speed (safety considerations may have to apply here, as attempting to generate high racquet head speed with isolated motions may put dangerous stress on relatively weak joints such as the shoulder, elbow and wrist). By employing this approach, the student has a series of well defined goals and can learn to discover good mechanics. As they progress, they can learn to keep their arm loose and relaxed, as they let the legs and torso (and hopefully "imprinted" patterns of muscle activation) guide the motion.

I'm going to test this out on friends, as well as myself. I'm thinking about teaching myself to serve with my left arm (I'm extremely right hand dominant), as I think this will be a good test of these ideas, and may also give me some useful teaching insights.

It's interesting that you would start at the final portion of the motion.

While this is the "action part" of the serve, it seems to me that an all out swing forward with pronation is what every tennis server sees as their most important goal.

But I would take a different approach.

I would concentrate initially on the attaining an aggressive trophy pose that emphasizes continuous balance as the tossing arm continues up, and the upper body turns away from the ball (coils) on a progressively greater knee bend and the body forms a bow shape with the a steep shoulder angle and front hip pushed forward.

It's not easy to get to that trophy pose in a controlled, balanced way while tossing the ball with the non-hitting arm.

But if a player is able to get to that position, he will posess the ability to "unwind" all of the elements in a kinetic chain: leg extension, uncoiling and cartwheeling.

It seems to me that most players initially focus too much on the racquet swing and hitting, and fail to adequately prepare. (It's what grabs their attention, and they will push hard to get that arm action down.)

But having an initial continuously balanced firm foundation of how to get the serve started allows the swinging/hitting to well up from all the other necessary body movements.

Plus, they will have learned a good tossing motion that incorporates the other body movements.

They will also have a view of the ball looking up from the end of that trophy position that will allow them to coordinate the hitting into a seemless serve.

When you learn to read it is a-b-c. When you learn to sing it is do-re-mi. When you learn to serve it is: toss-AND-coil/knee bend/bow
http://www.youtube.com/watch?v=CeZp90h-Ar8&feature=channel

Just my thoughts.
 

VikPopov

New User
FYB do a number of progression videos where they start at the final part of a stroke and add preceding parts. I did try their technique using my non-dominant hand so see how good it is as a teaching aid and I thought it was useful.
 

spacediver

Hall of Fame
thanks for the feedback.

charliefederer, you make some interesting points. I have close to zero experience actually teaching the serve, so a lot of my musings are theoretical.

Perhaps progressions can work both ways (forward and backwards), and each style will end up prioritizing different types of learning.
 
thanks for the feedback.

charliefederer, you make some interesting points. I have close to zero experience actually teaching the serve, so a lot of my musings are theoretical.

Perhaps progressions can work both ways (forward and backwards), and each style will end up prioritizing different types of learning.

I am sure over time different parts of the serving motion will have to be revisited again and again.

It has just been my observation that too many servers stuck at the <4.0 level never learn the secret that the whole body has to be in balance with a big windup to power a consistant first and second serve.
 

kiteboard

Banned
All bad servers never learn to bow the hip out and form an arch back.. They don't understand external shoulder rotation (forcing the shoulder back towards the net) vs. internal shoulder rotation (rotating into pronation). They don't understand radial deviation of the wrist (place your stick arm out in front of you and twist your stick hand to the right upwards) or ulnar deviation of the wrist (rotate the wrist to the left downwards), and the true nature of wrist pronation: a fully deviated path from right (during full coil/trophy pos.) to left (a full uncoil upon striking the ball). They don't understand that the leg drive is timed to increase external and internal shoulder rotation, and is straight up in the air, not towards the net. They don't understand that without a good toss, no one can serve well, high enough up, and in the right spot forward for first serves, and more back for seconds (kicks or twists) or still forward for more aggressive faster slice serves. They don't know how to twist the upper body on the intitial coil, nor how to unleash the twist into the pronated strike.
 
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