Last night the focus was on escaping from an attack which ends up with someone sat on top of you either punching or choking you.
A big thing was the bridge - thrusting your hips up and to the side to force the attacker off you. I've often seen the bridge described as a good posterior chain exercise. For example as described by Craig Ballantyne below:
This never seemed to me like a really useful exercise. Ok - it is about the only real posterior chain move that you can do with just bodyweight - especially if you just use one leg at a time, but it didn't seem useful..........Last night however things fell into place. This is a really important move! The videos below explain how important this motion is to get someone off you:
We drilled this a lot last night and I am sore today!