The "L" shape
One of the principles or concepts I've heard about from time to time over the years is the "L" shape. Specifically, we're talking about making a movement starts in one direction, and then at a certain point, changes direction, usually 90 degrees or perpendicular to the first line.
It's a wonderful principle, really, and while the reasoning behind it is simple enough, it still feels like magic when someone applies it to you. Uke feels energy going in a certain direction. Typically, he reacts by resisting, even just a little. A moment of tension is established. He can deal with that singular line of force or energy pretty well, his body structured is set to withstand it.
But when that line suddenly changes at a right angle, uke isn't prepared or his structure isn't set to deal with that line so he's very weak. A simple concept, but hard to internalize!
The first place I remember learning about had to do with a particular escape from kata gatame. Let's say uke is hold you on your right side. After you've "answered the telephone" and managed to get your right fist by your ear (between your head and the guy holding you) to create a little breathing room, you start by bridging with both legs and hips straight back (or up, I guess, toward your head). You can't half-ass it, either. You really have to drive.
Once you get as far as you can go you make a hard right turn as it were, turning toward uke. It tends to grind knuckles into the mat, so be nice. From there, you can weasel your way out any number of ways that I won't go into now.
"Look at your watch"
Another place I just discovered the other day is with hiza guruma. Man, I don't know what it is about that specific throw, but it seems like I'm always learning new insights on it! My fellow judoka Scott and I were just moving around the other day, and I don't know how we really came to it, but he was the one that started us down that road.
Let's say I'm trying to throw uke on his left knee, meaning I'm propping with my right foot. I'd always been taught to lift the right elbow, or "look at your watch." Lately, I've been playing with other options with that hand (namely based on something Bob Rea once mentioned about what he did, but now that I think about it, I may have misunderstood him all this time).
Now we were going back to the old elbow up/look at your watch method. What we found was once you do that, you've establish a certain line of force or energy, one that, if uke were trying to resist the throw, he could sort of brace against. But then we just yanked our hand straight down. Both of us would end up practically diving into the mat.
Basically, we were creating an "L" shape. If we started off pulling straight down to the floor, of course, we would be stabilizing uke, putting his weight into his own feet. But if did "elbow up" first, got uke's shoulders just a hair out in front of his hips and got him used to one line of force, and then pulled straight down, whoooooo-weeee.
Although, I did notice that it didn't exactly create the typical tobi ukemi, or flying, flippy air fall that hiza guruma usually does. Rather, uke would get somewhat vertical and then roll sort of sideways. I guess that's still technically a guruma, I don't know?
At any rate, it certainly was slick. I'm definitely going to be keeping an eye out for more "L" shaped instances, judo and aikido!