Keeping the kicking leg straight out

It is very important to keep the kicking leg straight out. In fact, this is an art form in itself. Requires a lot of skill. Anticipation of the opponent's move. Judgement of the distance between u and the target. And then the muscular strength to sustain the thrust in such a kick. Whether you are close or far from the target, make it your aim to keep the kicking leg straight. If close, then it means you pack in enough to punch to push the target out of his/its center. Only then will the leg open. If far away, straightening the kicking leg is quite easy. The tilt of the body/torso is adjusted according to how much you decide to keep that leg straight. When practising keep focusing on this aspect to give power to your kicks.