well conditioning goes with it but i think its more of a mental element...just that you need to go through with your actualy kick. any hesitation can cause serious injury to yourself which is why you would just go balls out with it
well the roundhouse kick can be powerful if utilized correctly, its not always about speed and stregth. But its more of like a tai chi thing as to how much power is behind it. Bruce lee is a perfect example. he knew how to utilize spower as appose to strength
Now no matter how good anyone is...there is always someone who is faster, stronger, smarter, more skilled. Who do you guys think is the best? Personally one of my favorites is Jackie Chan. But i think he is closely followed by tony jaa