In grappling, an Armlock is a single or double Joint lock that hyperextends, hyperflexes or hyperrotates the Elbow Joint And/Or Shoulder Joint. An Armlock That Hyperflexes Or Hyperrotates The Shoulder joint is referred to as a shoulder lock, and an armlock that hyperextends the elbow joint is called an armbar. Depending on the joint flexibility and integrity of a person, armlocks that hyperrotate the shoulder joint can also hyperrotate the elbow joint, and vice versa.
Obtaining an armlock requires effective use of full-body leverage in order to initiate and secure a lock on the targeted arm, while preventing the opponent from escaping the lock. Therefore, armlocks are usually more easily performed on the ground, from positions such as the mount, side mount, or guard. Armlocks are more difficult to perform when both combatants are standing up, though the stand-up variants are a focus in certain systems such as Chin Na. A failed armlock can sometimes result in the opponent escaping and obtaining a dominant position.
Armlocks are considered less dangerous techniques in combat sports allowing joint locks, and are the most common joint locks used as submission holds. In sparring or training, armlocks are generally done in a slow and controlled manner, so that the opponent can submit before any damage is inflicted. In self-defense application, or when applied improperly or with excessive force, armlocks can cause muscle, tendon and ligament damage, even dislocation, or bone fractures.
An armbar (sometimes called a straight armbar) is a joint lock that hyperextends the elbow joint. It is typically applied by placing the opponent's extended arm at the elbow over a fulcrum such as an arm, leg or hip, and controlling the opponent's body while leveraging the arm over the fulcrum. It is used in various grappling martial arts, including Brazilian jiu-jitsu, Catch wrestling, Judo, Jiu-Jitsu and is one of the most common ways to win a match in mixed martial arts competition. The technique has several variations, with the best known and most effective in competition being the juji-gatame. The juji-gatame is so common, that "armbar" is often used synonymously with juji-gatame.
The English word "bar" is used here to signify the opponent's extended arm, while the Japanese word "juji" (十字) refers to the armbar's visual resemblance to the number 10 as written in Kanji, 十. The word juji is also found in "juujika" (十字架), meaning a cross.
The technique is one of the official 29 grappling techniques of Kodokan Judo. It is one of the nine joint techniques of the Kansetsu-waza list, one of the three grappling lists in Judo's Katame-waza enumerating 29 grappling techniques. All of Judo's competition legal joint techniques are arm locks.
Video: Alabama Judo Federation Video channel by Sensei Tirdad Daei: Judo: Ude Garami: Arm entanglement or "figure-four" key lock http://youtube.com/watch?v=IOLx0GCwaDs
Kimura (Brazilian Jiu-Jitsu), chicken wing/double wristlock (wrestling), or reverse keylock are terms used to specify a medial keylock known in judo as gyaku ude-garami (reverse arm entanglement) or simply as ude-garami. The application is similar to the americana, except that it is reversed. It needs some space behind the opponent to be effective, and can be applied from the side control or guard. Contrary to the americana, the opponent's wrist is grabbed with the hand on the same side, and the opposite arm is put on the back side the opponent's arm, and again grabbing the attacker's wrist and forming a figure-four. By controlling the opponent's body and cranking the arm away from the attacker, pressure is put on the shoulder joint, and depending on the angle, also the elbow joint (in some variations the opponent's arm is brought behind their back, resulting in a finishing position resembling that of the hammerlock outlined below). The kimura was named after the judoka Masahiko Kimura, who used it to defeat one of the founders of Brazilian Jiu-Jitsu, Hélio Gracie.
The omoplata (sometimes referred to as ude-garami or sankaku-garami, 三角緘, "triangular entanglement or ashi-garami, "leg entanglement in Judo) is a commonly featured shoulder lock in Brazilian Jiu-Jitsu. The locking mechanism is similar to the kimura lock, but instead of using a figure-four, it is applied using a leg. The omoplata can be applied from the guard, by placing one leg under the opponents armpit and turning 180 degrees in the direction of that leg, so that the leg moves over the back of the opponent and entangles the opponents arm. By controlling the opponent's body and pushing the arm perpendicularly away from the opponents back, pressure can be put on the opponent's shoulder. It is also possible to put pressure on the elbow joint by bending the leg entangling the arm, and twisting it in a specific manner. Though an effective lock, it is more difficult than other armlocks to successfully apply.
A hammerlock is a shoulder lock similar to the kimura lock where the opponent's arm is held bent against their back, and their hand forced upwards towards the neck, thereby applying pressure to the shoulder joint. The hammerlock is well-known as a pain compliance hold in law-enforcement where it is typically used from a stand-up position to control an aggressor, and is also utilized in the application of handcuffs. It is also sometimes seen used as a submission hold in submission wrestling arts and professional wrestling.