So are there ways of pinning someone where they're in a position where they simply can't exert enough force to resist in any useful way, EVEN if they're willing to injure themselves?
I feel like there are, from my experiences as an uke. Sometimes I just feel like I'm in a position where there's nothing I can brace myself against so as to create any kind of force.... Maybe I just haven't ever tried to test it to the point of injury, but sometimes it doesn't really feel like it's pain or risk of injury that's stopping me from escaping. It feels more like I'm in a position where I'm more than usually weak.
Yep. There have been times I've told my nage, as I'm tapping, "you are causing me pain so I'm tapping, but you don't actually have me pinned
." A good pin might give me wiggle room to test it, but it is immobilization, not pain, that stops me short. A REALLY good pin gives me no desire to even test it.