The use of the knees in kicking holds a particular importance to my thinking and practice. In order to generate power in most kicks the movement of the knee is key. Without the knee exploding from a chambered postition towards the plexus most kicks will lack the force they could deliver. By using the center of your body you use your whole body, neglect this and you exponentially dimininsh what you want to do for almost every kick in the system. The non kicking leg maintains your root (especially with impact) and cannot be locked. the knee must bend and even sink with the kick and not striaghten out or lock. The return to the crane afterwards re indexes the spine and brings you back to center alignment and equilibrium…bring the knee back to your center. the further you move from these prinicples of the knee the less effective your kempo becomes.