Monday, February 26, 2007

Putting Theory To Practice: Newton's 3rd Law of Motion

"For every action there is an equal and opposite reaction."
Sir Isaac Newton

Last week, I understood a little more about how Newton's Third Law of Motion applies to karate. It was a typical post-practice scene, with Sensei and I talking story as I hit the heavy bag. And as usual, Sensei provided corrections and suggestions in between stories about his training on Okinawa, anecdotes about people he ran into that week, and some various musings we were both entertaining. Like I said, talking story. Sensei mentioned that I should push against the ground with my feet when I hit. This wasn't the first time I heard it, nor was Sensei the first person I heard it from. He pressed his foot against mine to let me feel how I should be doing it. Again, that night wasn't the first time. However, this time something clicked. Having my weight towards the outside of my feet as they pushed against the ground suddenly made it easier to keep good posture and to time the kime. It was easier to use koshi naturally and to employ hara... or, at least to feel it. It wasn't a perfect hit, far from it. But it felt good. No, it felt great. Certainly better than any of my previous tries that evening... maybe one of my better ones up until that point, period.

I already knew about Newton's 3rd Law and that whenever I pushed off the ground, the entire earth pushed back with the same amount of force. I already knew that I have the ability to walk, run, and jump around because even though the earth and I are pushing against each other with the same amount of force, I accelerate a lot more because the earth has far, far more mass than I do. Technically, I accelerate the earth by the merest fraction when I do this... we all do. And as I mentioned before, other styles tell their students to push against the ground during their techniques to take advantage of this wonderful earth-moving power, although whether or not their stance and posture maximizes this benefit is another matter.

But until my accumulated experience of trial and error from continued practice allowed me to understand it, all that knowledge was worthless in a fight. Knowing theory can only point you in the right direction. Knowing methodology gives you the opportunity to train properly. Training properly gives you experience. Experience is the difference between knowing and understanding, and understanding makes all the difference in the world.

"Knowledge is empirical and not intellectual. It is to be experienced and from experience comes understanding."
Sensei Pat Nakata

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bernie said...

Your wrist should turn just as your toe turns at the moment of impact. Aside from getting the increased force traveling from your foot to your fist, the twisting motion of your glove adds centripetal force to your target. If you have a small hand like I do, this is an advantage over a larger opponent since this force decreases with a larger diameter fist given the same mass and speed of the punch.

Bujutsu Blogger said...

Thank you for your comment, bernie.

To provide some more background information, we do not use gloves, since that prevents the forming of a solid fist. Furthermore, we hit only with the knuckle of the index finger instead of both knuckles. As you say, a smaller surface area creates more pressure. For that matter, we keep the hand and forearm completely tight during the entire range of motion, but the upper arm and shoulder is completely loose. This allows a solid fist with complete fluidity of arm motion.

We also delay the twist until the very end as you suggested. In our methodology, this allows the knuckle to drop down after we impact (not right before), which facilitates weight transfer into the opponent. To optimize this weight transfer, we do not twist the toe or move the leg while in a natural stance, since this causes some of the force to be lost as we understand it.

What is your background? I'm obviously an Okinawan karate guy (Shorin Ryu).

Bujutsu Blogger said...

Oh, and I forgot to mention one thing. You mentioned something about the mass of the fist. The mass of the fist does have some bearing on the amount of force generated, but since the body weight is transferred into the equation after impact, the mass of the fist is somewhat irrelevant to the total force generated. This is entirely different than whip mechanics, which many use to generate power for punching. In other words, the weight involved in whip mechanics would merely be the tip of the whip (the hand) and not the handle (the body). In our methodology, we prefer to hit with a baseball bat and use the total mass (hand and body). A rough analogy that won't stand up to extreme physics scrutiny, but one I still find appropriate.

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