Ferd--I should have more in-depth stuff on the "How-to Defend" thread later on. And I will address the Knee. I promise.
Ironman would be correct on the basis’ that he covered with the knee. I think I'll take it a step further and expound on a few things:
First thing to consider when throwing a knee (actually all strikes) is range. Most people think that Knees are purely "inside" weapons (aside from a jumping/flying knee), but the truth is that if you can reach out and touch someone with your hands you can knee them also. In fact, most of the texts I’ve read advocate that you have at least a hand on your opponent when you throw the knee, as throwing the knee generally upsets your base by leaving you with only one post on the ground. Further, your grip can be used to pull the opponent into the knee which benefits you twofold by helping you ensure that the knee will hit, and by helping the generation of force by accelerate your target toward you.
Knees should be thrown with a “rear leg” bias in order to generate any consequential stopping power. Even if you want to throw a knee with your front leg, you would have to do a quick “shift step” to change leads so that your front leg ends up cocked to the rear to fire. Otherwise you don’t have enough distance to accelerate your leg to generate the maximum amount of stopping power.
To throw a straight free-standing knee, or knee outside of the clinch (khow
in Muay Thai):
1) Push off your rear foot while you use your front foot to bring you forward (just like coming out of the bottom of a deep lunge).
2) Rotate the striking side of your hips toward the target.
3) Bring your knee in a straight line into your target, making sure to connect with the point of the knee.
4) Punch you hips forward as your knee connects (this makes the difference between throwing a knee, and throwing a knee with bad intentions).
The reason why knees are so damaging is the fact that the movement involved to throw a knee always effectively moves your total center of mass toward the target. This is unlike a punch that can be thrown “arm only” without the benefit of the rest of your body mass. Remember: Force = Mass X Acceleration
. As the legs account for anywhere from 30% to 40% of our body mass, the only thing you have to concern yourself (besides actually connecting with the target) is generating speed. On that end, throw knees with an emphasis on speed
as the mass is already there.
This vid here
is a great example of a properly thrown knee.