Getting out from underneath a heavier opponent when pinned face down

Question

I have an unusual question and I hope you can help me. I'm a fantasy romance writer and know nothing about fighting, although I watch a lot of Muay Thai and kickboxing.

So there's a sparring scene in my book. The main character is a highly trained assassin. In this particular scene, he's sparring with an opponent who is taller, heavier, and physically stronger than him; the opponent also has good technique, though not quite as highly trained. For demonstration purposes, the assassin allowed himself to be pinned to the ground by this heavier guy, who is pressing his knee at the base of his spine, trying to restrict his breathing (the assassin is face down, which is important).

How would the assassin get out of such a position?

What would he have to do exactly, if that's possible? I need to describe it in a couple of sentences and I need it to be realistic. Basically, I want to show off his skill and the ability to get out of a tight spot while fighting an opponent who outweighs him and finding himself in an unfavourable position. He is not allowed weapons.

If that won't work, could you suggest another position and escape that would demonstrate a high level of skill?

Answer 1

If the opponent is balancing on only a single knee to pin you down, the easiest way out is definitely rolling. First slowly bring your elbows in toward your torso and use your forearms as frames between you and the ground, do the same with your knees. We need a small amount of space between us and the ground for leverage to roll. Once our wedges are in place we are going to explode and rotate our hips and shoulders to face the direction of our opponents posted foot (meaning the foot they are using for balance, not the knee on the back).

This will probably land us in a position called mount, and still on the bottom which is still a pretty losing spot, but there are plenty of mount escapes we can use from here. For inspiration on those search youtube for "BJJ mount escapes"

Answer 2

Given assassins are generally known for using simple and effective (and not entirely sporting) maneuvers, I'd go with the self-defense technique of kicking the opponent in the groin. For someone to be pinning you​ down with one knee, odds are their legs are somewhat spread. Kicking up and back like trying to kick your own butt has a decent chance of hitting the groin, particularly for a flexible and precise combatant. From there, it's taking advantage of the distraction by rolling them off of you laterally, pushing up with the arms while twisting the hips.

If you want to make it sound less prosaic, have the assassin strike a "nerve cluster" in the leg or back. Basically the same thing, but it suggests the strike was precisely targeted, not blind flailing.

Answer 3

Training in Budo Taijutsu we practice this a lot. You can preform our postures either standing, sitting, or laying down. The posture is called ichimonji. By shifting your waist and spine your entire body shifts. This shift starts in the hips. It moves your opponent enough that you can throw them off you without much strength required. From there, if you have the strength left you can end up on top of their chest by rotating on your leg that was on the ground and throwing your other leg up and over; this opens you up to a whole lot of fun. I'm trying to find a video of it on the ground but I can't.