HAMMERLOCK

The hammerlock is the shoulder lock in which the attacker rotates the opponent's arm behind their own back, applying hyperextension force on the shoulder joint. The position resembles the gesture of pulling a chicken's wing behind its body, which is where the alternative name comes from. The technique is one of the older submissions in the catch-wrestling tradition and was inherited into Brazilian Jiu Jitsu via the early Gracie family integration of wrestling techniques.

The mechanics begin when the attacker has captured one of the opponent's wrists from a back-control or turtle position. The attacker pulls the wrist behind the opponent's back while controlling the elbow to prevent the opponent from rotating out, then applies upward force on the wrist to drive the shoulder past its functional range. The lock works because the shoulder's structural design does not accommodate full rotation behind the back under load — the rotator cuff and shoulder capsule reach their limit quickly.

The hammerlock is illegal in IBJJF competition due to safety concerns about rotator cuff injury, but legal in ADCC and most modern no-gi rulesets. It has historically been used more in catch wrestling, judo, and sambo contexts than in pure BJJ, but modern competitors who train across multiple grappling disciplines (notably the Russian and Eastern European sambo-influenced grapplers) integrate it into their broader submission vocabulary. Defensively the hammerlock is escaped by rotating the elbow forward to follow the lock, by tucking the captured arm tight to the body before the lock engages, or by tap-to-grip when the rotation has fully closed.