Hinges

I changed my mind.  Yesterday I said we were going to work all arm bars this week.  Today I decided we’d broaden our horizons to include “all” hinge joints in the body, by which I mean the knee and the elbow.

As one student pointed out, they’re very similar structures – they both only bend one direction.  So, if we take a bit of time and consider which way they do bend, we can then think about which way they don’t bend – backward.

There’s something magical about taking someone to the ground using this idea.  Suppose someone gets behind you and wraps you up in a bear hug but leaves your arms free.  One solution is to reach down, grab their heel with both hands and pull up while sitting down on their femur.  This will make them fall over because the knee joint doesn’t go that way.  If you’re mean enough to hang on to the heel and sit all the way down, you’ll land fairly violently on them and possibly give them a knee injury.  If you let go, they’ll simply fall over and you’ll be left standing.  Neat.  Just a moment ago they were upright and behind you in a great position… but now they’re on the ground – all because you understand which way a hinge joint can go and which way it can’t.