Article: Researching the Serve

[gzhpcu]

Part 2 of this article has a table mentioning some of the relevant biomechanical points, among which "ulnar deviation". No explanation is given in the text. Is this a movement of the wrist from left to right prior to impact of the ball? Isn't this something to be done consciously, as opposed to pronation, which occurs naturally if your arm is relaxed?

[BrianGordon]

ulnar deviation

Phil-

Ulnar deviation is sideways movement of the hand at the wrist - it is a movement in the direction of the "pinky" finger or ulna bone of the forearm - it is largely a muscular driven action occurring prior to contact (nearer the mid point of the upward swing) before pronation, also a muscle driven action, repositions the the wrist axis to allow flexion near contact - keep in mind the article is on a "flat" serve - the wrist joint movement can be roughly considered a circumduction during the upward swing - extension at the low point --> ulnar deviation at the mid point --> flexion near contact - Brian

[vmiller]

Hi Brian, great article!

In the article, you say that wrist torque is motion driven, but here you are saying that it's muscle driven. Maybe you are talking about two different wrist movements? What am I missing?

I thought the reference to the tricep/nerve experiment was great. I guess it confirms the advice to keep a loose arm.

Have you come up with any teaching implications based on your findings?

Thanks,
Vin

[gzhpcu]

Thanks Brian, yes great article. An additional question: When hitting a spin serve, does one think of doing an ulnar deviation prior to impact, as opposed to pronation which just naturally happens? Is the unlnar deviation a contributor to allow hitting across the ball in addition to hitting up and forward?


edited for clarity

[BrianGordon]

muscle vs motion

Hi Vin-

The ulnar deviation component is clearly muscle driven. The article refers to the late flexion of the wrist near contact - I have pretty compelling evidence about that but not enough measured subjects to go public - when I do perhaps I'll write something up about the kinetic contributions at all the key joints - depends if the readership can stomach this level of analysis. The teaching implications are vast - particulary the role of trunk twisting rotation which is largely overlooked in serving technique - but really all the actions have coaching AND training implications - this contribution breakdown is one of the cornerstone analysis tools we use at our training and development centers in Cincinnati - the first to systematically use Applied Sport Science as the foundation for player development - had to get a plug in - cheers - Brian

[BrianGordon]

ulnar deviation2

Thanks Brian, yes great article. An additional question: When hitting a spin serve, does one think of doing an ulnar deviation prior to impact, as opposed to pronation which just naturally happens? Is the unlnar deviation a contributor to allow hitting across the ball in addition to hitting up and forward?


edited for clarity

Phil-

To be honest I've never done work on spin serves - I don't believe pronation happens "naturally" on any stroke, serve included - I can think of several instances where supination may be motion driven - but I digress - answering as a coach and player, ulnar deviation is the wrist action near and at contact on any form of spin serve used to, as you put it, hit across the ball. Wrist flexion would not come into play on a spin serve, nor would pronation - Brian

[mrhalley]

Leg Thrust contribution?

You analysis of motion starts AFTER considerable force has been generated by pushing off against the ground and thrusting upward.

What is the contribution of the knee extension? Given the size of the muscles involved, this force must be very high. I suspect that is where most of the force is generated. The remainder of the force is a linkage through the body segments.

[BrianGordon]

leg drive

You analysis of motion starts AFTER considerable force has been generated by pushing off against the ground and thrusting upward.

What is the contribution of the knee extension? Given the size of the muscles involved, this force must be very high. I suspect that is where most of the force is generated. The remainder of the force is a linkage through the body segments.

Excellent observation - my work here by design dealt with only the upward swing - it also dealt with kinematic factors such as veloicty, not kinetic ones such as force - the legs are where much contractile force is generated which accounts for nearly all of the ground force elicited. This of course happens during the back swing for most high level servers. The leg "thrust" is important for at least the following reasons:

1. the back swing racquet path/arm characteristics of (a)depth of racquet drop, (b)priming or loading of the shoulder joint complex musculature, and (c)joint safety associated with that priming.

2. aiding hip joint muscles in initiation and maintenance of pelvic rotation.

3. eliciting the ground reaction force that provides angular momentum to the entire system (body+racquet).

In short the leg trust provides the kinetic fuel to facilitate the kinetic joint interactions that CAUSE the segment and joint rotation I describe in the article. This fuel is CRITICAL to the development of racquet speed.

Nice point mrhalley - Brian

[yves]

ulnar deviation: volountary and consicuenciuous action?

Dear Brian,

is teh Ulnar deviation on the serve is Volountary action and consciencious from the server ?? or is it the result from the speed and forces generates by the others factors ; muscles and joint action before ???

thanks for your reply
Yves

[BrianGordon]

ulnar deviation 3

Dear Brian,

is teh Ulnar deviation on the serve is Volountary action and consciencious from the server ?? or is it the result from the speed and forces generates by the others factors ; muscles and joint action before ???

thanks for your reply
Yves

Yves -

My data and the data of others that have measured such things indicates it is mostly a voluntary, muscle driven joint torque at the wrist - qualitatively this makes sense as the forearm is angularly accelerating at the time in question so the motion dependent torque would be in the opposite direction or radial deviation. As such (in response to your email) it is musclular action that should be trained - we use a weighted lever with low resistence - but more than the weight of the racquet.

Brian

[gzhpcu]

The ulnar deviation has another benefit: when serving to the ad court, you can really serve wide to the backhand.

[mrhalley]

Kinetic chain is an interesting phenomenon

Excellent observation - my work here by design dealt with only the upward swing - it also dealt with kinematic factors such as veloicty, not kinetic ones such as force - the legs are where much contractile force is generated which accounts for nearly all of the ground force elicited. This of course happens during the back swing for most high level servers. The leg "thrust" is important for at least the following reasons:

1. the back swing racquet path/arm characteristics of (a)depth of racquet drop, (b)priming or loading of the shoulder joint complex musculature, and (c)joint safety associated with that priming.

2. aiding hip joint muscles in initiation and maintenance of pelvic rotation.

3. eliciting the ground reaction force that provides angular momentum to the entire system (body+racquet).

In short the leg trust provides the kinetic fuel to facilitate the kinetic joint interactions that CAUSE the segment and joint rotation I describe in the article. This fuel is CRITICAL to the development of racquet speed.

Nice point mrhalley - Brian

Brian,

Your analysis is great. I was just thinking that force creation in tennis is just like baseball or football or golf, pushing against the ground and then the force is transferred through the kinetic chain. This kinetic chain is a very interesting thing and it would be interesting to know how it actually works. Obviously, racket speed is not genreated by strength alone. Pro tennis players are not as strong as football players, but they sure can hit the ball harder.

Many articles refer to the kinetic chain, but I have found little that explains how it actually works. Good dissertation topic for the next time

[BrianGordon]

kinetic chain

Brian,

Your analysis is great. I was just thinking that force creation in tennis is just like baseball or football or golf, pushing against the ground and then the force is transferred through the kinetic chain. This kinetic chain is a very interesting thing and it would be interesting to know how it actually works. Obviously, racket speed is not genreated by strength alone. Pro tennis players are not as strong as football players, but they sure can hit the ball harder.

Many articles refer to the kinetic chain, but I have found little that explains how it actually works. Good dissertation topic for the next time

The reason you have found no explanation is because the authors are intentionally vague. The kinetic chain is interesting but using it to generate racquet speed has very little to do with "transfer" of force. That is not to say force generated from the ground is not important. Therefore the ambiguous description you've seen, that you build strokes from the ground up, is a good concept that players and coaches can grasp and benefit from - it does not remotely explain, however, how the "chain" works. John and I have spoken of an article on this very subject - perhaps down the road - Brian

[gzhpcu]

Brian,
I have brought this up before, but it would be interesting to be able to analyze Roscoe Tanner's serve (I know this is difficult since he is not playing as a pro anymore...), simply for the fact that he had a no-frills serve, low toss, with a fast concerted movement (absolutely no pause) and blinding speed. As I remember it: no excessive jumping, twisting, etc., yet a very heavy and fast serve.

[yves]

Re

Dear Brian,

thanks for you reply , I will test to train it

cheers
Yves