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Stepping out and cutting in

May 16, 2009

Here’s a hard concept – when using a katana, there’s no distinction between a cut and a step.

At this point, about 98% of the readers (can you have 98% when probably only three people are reading this?) are saying, what the hell? Obviously, a cut is a sword motion, and a step is a body motion. How can there be no distinction? That’s pretty much the reaction I get from my students when I say that sort of thing, and even when I demonstrate it, I get the impression that they’re mostly just humoring me. The other day, I did a bunch of cuts with one of my students as a warm-up exercise – at the end, he was sweating and panting, and I wasn’t even slightly winded. Am I in much better shape than he is? Doubt it. I’m just doing less work.

So, here’s the story: a cut is powered by the core of the body. While it’s possible to do a cut without moving (which is a different story, though the basic principles are the same), normally one makes a step, and the line of the cut follows the line of the step. So, a step back at 45 degrees results in a cut that pulls down at a 45-degree angle; a step straight to the side results in a horizontal cut. So, you’re saying, OK, the cut and the step have to be in the same direction in order for the power of the step to be expressed in the cut, but they’re still two different motions, right?

In order to really get this, you have to understand what constitutes a step. Every step involves three turns of the upper body – when you extend your foot, the body turns away from that foot; when you shift your weight, the body turns towards the formerly-unweighted foot; finally, when you stabilize your center on the new base, the body turns to the inside, away from the foot. For example, if you’re stepping with the right foot, the body turns left-right-left. For a small step, the turns are very small, but they’re still there.

Those turns are the source of the power for your cuts. Take a horizontal step as an example, since it’s the easiest to picture. Obviously, if you hold the sword out in front of you and just slide your body to the side, the sword will follow a path that could cut, but it won’t have any power. However, when the body makes its second turn, the one that goes towards the destination foot, your body movement and the turn will combine to move the sword. At this point, the sword is moving several times as fast as your body, because it’s out on the end of a several-foot-long lever (your arm), which is turning through maybe 45 to 60 degrees for a flat horizontal step (remember, you start and finish by turning back, so that middle turn has to be actually the sum of the other two if you’re going to end up facing the same direction).

Now, we have the sword moving quite fast through the air, along a nice straight line. But there’s more – given good structure through your arm, you’ve got your whole body mass behind that sword. Since you’re not changing the angle of your shoulder during this process, in order to stop the sword, the target would have to stop your step completely. Force = mass * acceleration, and you’ve got a lot of both. This motion yields an extremely powerful cut, and here’s the best part – there’s no arm motion at all! The only muscles you’re using are the ones involved in the step, specifically the core muscles that drive the turns. That means that you can do this all day, and the only effort you’re expending beyond simply stepping back and forth is literally just holding the sword up against the force of gravity.

Of course, like everything you can put into words, this is all a simplification – some arm motion is unavoidable unless you’re ridiculously tense (see my earlier posts :-)), the motion of the step isn’t really linear either in direction or speed, and so forth. Also, if you’re doing a cut that’s not yokogiri (the horizontal cut), you’ll need some vertical arm movement to get the sword to follow the correct line. That said, the basic concept is correct – all the actual power comes from that turn, and the shift of weight, both of which are driven by the core muscles. This is one of the hardest (physical) concepts to get when using a heavy weapon, and it’s why the students always seem to be working so much harder than the teacher.

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