Like I said, when it comes to kumite, k-1, kickboxing, ufc, pride, whatever, the actual attacks most commonly used whether karate, kickboxing/muay thai are roundhouse kicks, front kicks, and thigh kicks. There's not a huge difference when you get down to brass tax. Other attacks are effective in specific situations provided you are proficient in using them: back kicks, axe kicks, side kicks, crescent kicks, but these situations don't arise frequently, and especially not in sport fighting.