Knee
A knee strike (commonly referred to simply as a knee) is a strike with the knee, either with the kneecap or the surrounding area. Kneeing is a disallowed practice in many combat sports, especially to the head, downed opponent. Styles such as Muay Thai and several mixed martial arts organizations allow kneeing depending on the positioning of the fighters. Knee strikes (particularly to the groin for males) are generally agreed to be effective self-defense maneuvers.
Straight
The straight knee (also known as a front knee) is a typical knee strike, and involves thrusting the front of the knee into the head or body of an opponent. The straight knee can be applied from a stand-up position both when the combatants are separated, or when they are clinching. A particularly effective clinching position for throwing front knee is the double collar tie, where the head of the opponent is controlled. On the ground, front knees can be effective from a few top positions such as the Side control and north-south position. Typical targets for the front knee include the head, hips, ribs, solar plexus, stomach and thighs. In Muay Thai, a double collar tie with a front knee to the face was traditionally called Hak Kor Aiyara.
Curved
The curve knee (also sometimes called a side knee) is similar to the front knee except that it does not use a forward thrusting motion, but is instead rotated from the outside. Whereas the front knee needs some space in between the combatants to be performed, the curved knee can be executed from a minimal distance, such as in a close clinch. Typical targets include floating ribs, hips, and the side of the abdomen.
Flying
A Flying Knee (known as hanuman thayarn in Muay Thai, and sometimes called a jumping knee) is a knee strike very similar to a front knee, except that it is performed in stand-up fighting by jumping, and often by rushing towards the opponent. A more reckless application of the flying knee strike can be applied by rotating the body so that the side of the knee strikes the opponent, used more as an offensive pushing attack rather than a concussive KO attack. Generally, flying knee strikes can be effectively applied when the opponent is off-balanced, recovering from previous strikes, or as a counter to a strike by the opponent. It can also be used as a follow-up maneuver after delivering a particularly incapacitating strike. One such example of this was at a UFC event where David Loiseau, after buckling his opponent Charles McCarthy with a Spinning Back Kick to the abdomen, immediately charged in with a flying knee, knocking McCarthy down against the cage and finishing the fight via technical knockout.
