Defense in jiu jitsu, it seems to me, is fundamentally about first response. If you make the right first decision to stack against an armbar from the guard, to posture against a triangle choke, then I'd bet you're halfway home to escaping and more than halfway home to at least not being submitted "right now." I like to think of the necessary series of moves to escape a bad position. But what seems increasingly important is to make the right first move--if only to give yourself a few seconds to process a more complete escape.
Against the triangle choke, this means pulling from the basic rules ("posturing") and the basic escapes (Mamazinho's "C.C. Grinder" and Pereira's "Midget Slam") the key "first response" that makes them work. Right now, that first response, seems to be to come up on the knee ("Knee Up") on the same side as the trapped arm in the triangle choke.
I've written before about watching OTM's 101 Submission Series and noticing that nobody who was shown tapping to a triangle choke so much as tried to come up on the trapped side knee. It was amazing to notice that. Plenty tried to come up on the other knee but that never worked. The problems with going Knee Up on the choke side are enormous. For one, the guy on the bottom can underhook that Knee Up to get an even better angle for the choke. It's really the self-defeating equivalent of trying to stand out of an armbar from the guard.
Even if the guy on the bottom doesn't take advantage of a Knee Up on the choke side, the second problem is that the physics of the defense are wrong in terms of leaving you vulnerable to both a sweep and further choking. With regard to the sweep, I'm reminded of the point Cesar Gracie makes in the "passing the guard" portion of his instructional DVD. You want to make sure that your base is covered. With one arm trapped in a triangle choke, you are vulnerable to being swept in the direction of that trapped arm. Going Knee Up on the choke side doesn't nothing to change that. Even worse, it exposes that leg to an underhook that can lead very easily to a sweep or further choking (see previous paragraph).
With regard to "further choking", the problem is that a Knee Up on the choke side actually makes the choke worse. Instead of the choke simply being between pressure on your arm against your neck on one side, and the guy's leg against your neck on the other--which obviously is bad enough--the choke is amplified by the squeezing effect the Knee Up on the choking side has on your upper body. And the more you push off with the Knee Up on that side, the more you push yourself into the choke that your arm is complicit in on the other side.
In contrast, going Knee Up on the trapped side actually helps relieve the pressure of your arm against your neck by helping push your shoulder forward (which moves your upper arm forward). When you consider how we're always told when doing the triangle choke to get as little "shoulder" into the choke as possible, you can see why going Knee Up on the trapped side helps.
Going Knee Up on the trapped side also provides you with the strongest possible base from which to regain posture. I've had well-meaning teammates shout "posture!" to me from the sidelines on more than one occasion. But what I've needed was to understand the actual mechanics of regaining posture, the action, not just the goal. Against the triangle choke, getting the Knee Up on the trapped side is the action--or at least the first one.
With the Knee Up on the trapped side, it is easy to see how you can shift into either the C.C. Grinder or Midget Slam escapes. With the C.C. Grinder, that Knee Up on the trapped side will be the knee that you drive into the bottom guy's chest as you grind counter-clockwise, the trapped hand bringing the gi collar across the throat like a slow-motion hook to the jaw. With the Midget Slam, that Knee Up on the trapped side gives you the leverage so that after you've got your hands on the knee of the choking leg, you can twist down and hard, pinning that leg on the mat.
