The Kinetic Chain

[stotty]

Hi Everyone,

I was wondering if someone could clarify the kinetic chain process.

Is the correct sequence

1. Coil torso, load then drive with legs and let ground reaction force unwind the torso to send the arm flying

2. Coil the torso, load and drive with the legs, then physically rotate the torso and then physically extend the arm through the shot

3. Coil the torso, load and drive with the legs, then physically rotate the torso and then let the arm go through with the momentum generated.

4. None of the above!

Many thanks in advance!!

[johnyandell]

Doesn't it go legs, torso, arms? Somebody help me out here.

But to me the so-called "kinetic chain" is an explanation of how the body does certain things, not a description of what the body is actually doing.

For example, in the full turn position on the forehand, the outside leg is coiled, the shoulders are turned at a certain angle, the left arm is stretched, etc.

The positions for the rest of the stroke follow. If the extension point in the swing is in a certain place, the body can find it--it may be superfluous or even counterproductive to try to make these positions by trying to control the complex (and natural) interplay between the body segments.

Having said that, maybe someone can still give a better description of how this term is used and what it means.

[oliensis]

The metaphor that works for me (and for martial arts students I've had) is that the effort goes into drawing the bow (in this case, getting into the "load" position in which potential energy is maximized--on the forehand that would be w/ legs loaded, torso and shoulders turned), and then you just let it go. And that's what validates the "chain" metaphor in the phrase "kinetic chain."

Of course physiologically it's more "active" than just letting it go (muscles contract as legs drive through, stomach muscles, and so on...), but the sense of the body as a set of loose and linked parts helps one to allow the transfer of momentum from one link of the chain to the next (legs, waist, shoulders, arm) to be additive (or even exponentially multiplicative).

One of the best metaphors I've run across is in T'Chi:
Heart directs mind. Mind directs ch'i (internal energy). Ch'i directs body. (I would preface that 3-part phrase w/ "belly directs heart."

This last may be a way of saying that it might be better to focus on getting into the "load" position and then just focusing on what you're doing to the ball rather than on your own body.

So, in one way, I think it starts with the legs and the rest of the body follows. But in another (maybe more important way) it starts with the intention and the body follows naturally. (Which may be the same thing as what Mr. Yandell was saying.)

[stotty]

That's great input both of you- thanks! I've mentioned to John already that the more I read books etc., the more confused I get!

I've read up about the chain a few times before and some authors mention coupling time which is the time you have in which to contract the muscles after pre-stretch before you lose the potential elastic energy, I think it's around 0.2 of a second. They talk about doing this for the obliques in the core which led me to believe that you do have to physically fire the torso.

Anyway, I will put what you both say into practice and let you know how it goes!

[bottle]

I Hate the Stupid Kinetic Chain

And I'm not the only one.

The USPTA pro who gave me my basic lessons, Jim Kacian, called it "Cartesian" thinking. To my mind that means too left-brained and logical
and going in a clod-hopping sequence.

Today, for instance, I found some success in serving by slowing up my elbow twist up and to the inside and then, as racket tip was relaxedly approaching low point, cocked hard to the outside with forearm muscles to accelerate the rest of the serve.

That meant forearm muscles first and triceps muscle second-- ono, a violation of KINETIC CHAIN AND PROBABLY THE MAGNA CARTA TOO!

[bottle]

If not Kinetic Chain, then What?

Jim liked "I am a snake" better.