isometric/concentric/excentric

[Dana Sheets]

short definition :
isometric training : when the muscle works but stays at the same length.
concentric : when the muscle increases volume while shortening
excentric : when the muscle works while stretching.

Bill & anyone else - can you frame (or tell me where I can read) how the traditional sanchin kata practice (1 slowly, 1 with dynamic tension, 1 with explosive power) around these three terms? Or use traditional exercises that would be familiar to everyone?

I'm afraid the only one I've heard of before is the first - and my brain references Jack LaLane and that's about it.

Thanks,
Dana

[Brian Barry]

I'm sure Bill will go into more detail with this but I'll add my two cents for the sake of immediacy.
I'll use the bench press for an example.
Your pectoral muscles are the ones that are contracting, doing the work. Do they do work only when you push up? I hope not, otherwise you are just letting the bar drop when you move it back down to your chest. So here is how it works.
Concentric action: Pushing the bar up, your pecs are working as they shorten.
Eccentric action: Letting the bar down in a controlled manner, your pecs are working while lengthening.
Isometric action: This would occur if you just held the bar still, but is done best when you do a typical squeezing your hands together at chest level. Your muscles are working, but they are staying still.

Concentric contraction has the most applications in everyday activities, as you will see in our striking.
Your muscles, however, are strongest on eccentric movement. This is where negative lifting comes in play. Back to the bench press, a weight that is above your max is placed on the bar and you slowly let it down. Your spotter(s) help you lift the bar back up and then you let it down again slowly. Though this gives you a chance to work with higher weight than normal and is considered by some to be helpful at increasing your maximum lift, it is difficult to directly apply eccentric contraction to many everyday situations.
Isometric work is actually, I believe, seen more in Uechi-like martial arts than in the majority of sports. Consider Sanchin kata. Practicing staying in your stance without moving is an isometric movement. Even when movement is performed, enough of the body stays still that those parts are still working isometrically.
However, isometric practice only increases the strength of the muscle at one position. So, as far as movement is concerned, why would an all-out isometric contraction benefit you any more than an all-out concentric or eccentric contraction? Consider:

Only one or two seconds are required to take a curl from thigh level to chin height. The hardest part of the curl is not the start or the finish, but instead the middle of the curl, where leverage causes the greatest effort. Yet the muscles are in this position for only a fraction of a second. With isometric contraction, the muscles would be exerting full force in this position for twelve seconds, so, theoretically, one effort here could build as much strength as more than a dozen repetitions performed in the conventional fashion.
--Little, John. Bruce Lee, The Art of Expressing the Human Body. p. 36

If isometrics are used to strengthen the muscle at the location where it has the least mechanical advantage in a specific movement, it increases the overall load that the muscle can bear over a full range of motion.

Now, dynamic tension. This is interesting, because you are working one muscle concentrically when you are moving the other muscle eccentrically. An example: lets look at your biceps and triceps as you straighten your arm. Your tricep is shortening, going through a concentric contraction. But your bicep is lengthening, going through an eccentric contraction. Both muscle groups are doing the work against each other. Then you start to bend your arm. Suddenly, your biceps are going through the concentric contraction while your triceps are going through the eccentric contraction. But they are both still working. You are providing resistance for each muscle group from the other group. Talk about multitasking. However, dynamic tension would not be directly applied in an altercation. You would not want one muscle group slowing your motion when the other group wants to strike. Otherwise you'd eat up a lot of the power you can generate. However, dynamic tension can be great at training your muscles to fire with maximum power during the entire range of a striking motion.

Is any one the best way to go? I don't think so. I work my muscles in all three ways. Explosive motion is almost entirely a concentric movement, but isometric action is clearly a part of our system also, and both isometric and eccentric work can be done to maximize our concentric abilities.

I may be totally off on some of this but if I am I'm sure somebody will tell me.

[Bill Glasheen]

Not bad, Brian.

Eccentric action = Muscle lengthening. It's "cocking the trigger" so to speak. When you are chambering in sanchin, you are engaged in an eccentric action with respect to ALL the muscles that will be firing later on during the thrusting phase of the sanchin kata (from the legs, hip, and waist all the way up the body to the pectoralis and triceps). In a jumping motion, it's that squat down before the jump.

Eccentric training is working a muscle in the "negative" part of the action, as in the way down on a bench press as described above.

Concentric action = Muscle shortening (contraction). It's firing the gun after having cocked the trigger, so to speak. It's what you do in the thrusting phase of sanchin, from the legs, hip, and waist all the way up to the pecs and triceps. In jumping, it's the leap up after the squat.

So in the body of sanchin, the chambering is an eccentric motion, and the thrusting is a concentric motion.

When you are engaged in dynamic tension sanchin (as in Goju), you are engaged in both eccentric and concentric training, as you are working the thrusting muscles both on the way back and on the way out.

Remember that all of this is relative to a motion. If you are pulling something, then you have to think in reverse. Eccentric is letting the oar go forward, and concentric is pulling it to your chest. A grappler often thinks of grabbing and pulling.

Strictly speaking,

Iso*metric = Same position.

Practically speaking, isometric training is a maximal or near maximal contraction while in a static pose. If you are doing kami (jar) training, your fingers are engaged in an isometric contraction while holding the jars. Folks like myself engage in sokusen training in the Uechi kata. Wherever there is a sagi dachi (crane stance) followed by nekko ashi dachi (cat leg stance), I touch down on the sokusen toe and perform an instantaneous, isometric contraction down into the floor. I simultaneously perform an isometric contraction of my tiger hands, as if I am gripping a football and trying to dig my finger tips into it. Usually when doing an isometric exercise, you think of pushing against an immovable object, such as sokusen pushing against the floor. You don't usually think of agonist and antagonist simultaneously contracting maximally (with net zero movement), but by the strict definition of the term the hands are also engaged in an isometric contraction at that point.

With that in mind, we really are engaged in some isometric contraction of the hand (hopefully) whenever we hit something. Otherwise we really aren't going to be penetrating well and we aren't protecting the hands. That's part of what you learn (or are supposed to learn) in sanchin at the end of the thrust. No floppy hands!!!

Hope that helps.

- Bill

[Akil Todd Harvey]

Many Thanks All,

For the question, as well as the answers.......ATH

[Dana Sheets]

yes - this is really worth digesting.

Would make a great topic in the "articles" section of this site as well.

Brian & Bill - you should should type up a draft & submit to George. This is the kind of learning that demystifies the different types of training in the Martial Arts and identifies why old time practices were or were not effective.

Thanks!

Dana