Roundhouse kick
A roundhouse kick (also known as a round kick or turning kick) is a kick in which the attacker swings his or her leg around in a semicircular motion, striking with the front of the leg or foot. This type of kick is utilized in many different martial arts and is popular in both non-contact and full-contact martial arts competitions. The kick has many variations based on stance, leg movement, striking surface, and the height of the kick.
Tae Kwon Do Method
The taekwondo roundhouse kick is performed by first drawing the knee straight up in a "chamber" position. This chamber, identical to the chamber of many taekwondo kicks (front kick, side kick, etc.) is utilized so that the opponent cannot guess which kick will be thrown. This differentiates it from Muay Thai, karate, and other roundhouse kicks, which tend to incorporate rotation before or during the rising of the knee. The knee is then rotated so that it is nearly parallel to the ground (counter clockwise for the right leg roundhouse) and the kicking hip is simultaneously rotated towards the opponent. The rotation of the hip, combined with the snapping of the leg forward, gives the kick its power. The striking surface is the instep or the ball of the foot. This is also called an "off the line" or "rear leg" roundhouse kick.
A similar kick is the front leg roundhouse, or "pop kick." To begin the front leg roundhouse kick, the leading leg is drawn up vertically, then rotated and snapped towards the opponent in the manner described above. The fast kick version is done by skipping forward with the rear leg, moving the kicker towards the opponent while simultaneously chambering and snapping the front leg roundhouse. The front kick is generally weaker than the rear leg roundhouse because the hip does not rotate as far; however, it is also generally faster because the leg travels a shorter distance before striking the opponent.
Muay Thai Method
As with many other Muay Thai techniques, the roundhouse kick has gained wide popularity due to its extensive use in mixed martial arts (MMA) competitions due to its effectiveness in inflicting damage to the opponent, as a properly executed roundhouse kick has been compared by many martial artists to being struck by a baseball bat. It is generally used in varying levels (low, middle, high) to inflict damage to different parts of the opponent's body. Low kicks generally target the thigh just above the knee joint for the purpose of weakening the leg, which serves many purposes such as limiting the opponent's mobility and potentially his ability to stand on the leg altogether. Middle kicks target the area above the hip bone and can damage the opponent's ribs and liver. High kicks target the opponent's head and have been responsible for numerous knockouts in competition.
There are several traits which give the Muay Thai Roundhouse a very different feel and look. The main methodological difference is that the person delivering the kick will raise up on the ball of his foot while he kicks, mainly to allow for greater pivoting/turning speed, and increased power (this method obviously has it's detractors, as not all martial artists agree that the ball of your foot is where you should be in a roundhouse kick). The person will also follow through with his hips, as the power of this kick comes from the pivoting of the hips instead of snapping with the leg, which stays relatively loose during the kick. Additionally, Muay Thai roundhouse kicks use the shin to make contact with the target instead of the instep of the foot. This further adds to the power of the kick, as the shin is more durable than the foot.
The practical difference is the objective of the kick. A standard karate or tae kwon do roundhouse kick has you snap your instep at your objective, but a Muay Thai roundhouse often uses the combined momentum of the snap and the speed of the leg to offer a faster and more powerful kick (albeit at the cost of control, in the opinion of some). Because the kick is executed with so much speed and power, a missed kick requires the kicker to continue spinning a full 360 degrees back to their starting position.
In Popular Culture
Roundhouse kicks were introduced to the West by the spread of Eastern martial arts. Possibly due to the move's combination of motion and power—the attacker spins fully around, which makes for a powerful-looking attack—it became a prerequisite feature in many fighting video games (either as a combination attack or a finishing move) and a common 'finishing move' in martial arts sequences in film and television. The latter case is best exemplified in Walker: Texas Ranger, in which the lead character (played by Chuck Norris) almost always defeated the episode's villain with a reverse roundhouse kick, inevitably to the head, shown twice from different angles. In professional wrestling the roundhouse kick is often referred to as a shoot kick because of its association with shoot-style wrestlers.