Originally Posted By: "MAGon"
Having only Karate as a background for striking, I learned to do knee strikes in the manner taught by this art. At least in the styles I've been exposed to, there are only two knee strike techniques, front and roundhouse. Variations are limited only by the Karate-ka's imagination, but they're all arguably variations of these.
Now, I wont get into the front knee strike, as by and large all striking arts that include it in their arsenal roughly do it the same way. The roundhouse knee strike, though, is a different story.
As I was taught to do it, the Karate roundhouse knee strike is performed almost exactly as 66% of a roundhouse kick, the missing 33% being the extension of the lower leg to strike with the foot. I.e.: The strike is chambered by bringing the leg up more or less into the "dog peeing" ( wink ) position. The strike comes from simultaneously pivoting the body inboard, using hip rotation, while bringing in the knee to the body's centerline by using the muscles of the thigh and abdomen. So some large, strong muscles are utilized to power the strike. Among favored targets are the sides of the opponent's body.
So all of the above was to get to this point: I've been intrigued for some time by a knee strike I've seen used in matches by Muay Thai and MMA fighters. Not ever having set foot in an MT or MMA gym, I can only go by what I've seen as to how it's meant to be executed. But it seems that the proper form is to bring the knee up close to the opponent's body, similar to chambering the leg for a front kick. More or less at the apex of the movement, the knee is brought to the strike by pivoting the body inwards and using the adductor muscles of the thighs to bring the knee to the centerline of the body, striking the sides of the opponent'. What's different about this technique compared to the Karate roundhouse knee strike is that the knee and thigh are held vertically while hitting, instead of being brought in more/less horizontally or obliquely. It seems to me that this MT/MMA technique is powered in the main by comparatively smaller, weaker muscles and that its power suffers in consequence (see the attached vid.).

So here's where I'd like to get y'all's opinion: Is there an advantage so solid to striking an opponent's sides a la MT/MMA that it compensates for the substantially less powerful resulting blow, as compared to the Karate roundhouse knee? Thoughts?
Just when you think something is foolproof, they come out with a new and improved type of fool.