A Roundhouse Kick (also called a Round Kick, Turning Kick, or 돌려 차기 dollyeo chagi) is performed by first raising the knee of the kicking leg so that the knee is aimed toward the target, as with a Front Kick. You then pivot on the balls of the non-kicking foot and turn the hip over slightly so that your body is turned sideways toward the target. The leg is then straightened to kick, so that the shin of the leg is moving in an arc that's parallel to the ground as you are kicking.
- In some versions of the roundhouse, the striking surface is the top of the foot. In this case, the ankle is held straight in-line with the rest of the leg and the toes are likewise pointed straight in-line with the foot.
- It is also very common to kick with the bottom of the balls of the foot. In this case, the ankle is bent upward and the toes are likewise bent upward.
The Non-Kicking Leg:
As mentioned above, the non-kicking leg is vital in this kick. In order for your body to rotate so that your side is facing the target, it is vital that you pivot on the balls of the non-kicking foot. In fact, at the moment of the strike, your non-kicking foot should be turned so that it's pointing away from the target.
Torso and Arms:
For this explanation assume that you are kicking with the right leg. While you are turning and kicking, the right arm should be brought down to the right so that it provides a counter-rotation to the kicking leg. In fact it is not uncommon to see people place the right arm all the way down behind the right leg at the moment of striking.
One principle of taekwondo is the principle of action and reaction where (for example) if one arm is moving forward, the other arm should be moving back. In the case of that Roundhouse Kick, that principle is applied by having the right arm move backward while the right leg is moving forward; the right arm is providing the reaction for the right leg.
The left arm is held close to the body, fist closed as if to block. The torso is turned sideways to the target and leans somewhat away from the target.