Glossary /// Alias
Arm-out rear triangle escape
Also known as Back Triangle Escape — the canonical term used on this site.
Training background: the version with both arms outside the legs
Descriptive — rear triangle with both arms outside
Arm-out rear triangle escape is the descriptive name for rear triangle defence, the version with both arms outside the legs — which makes it substantially faster and less forgiving than its arm-in counterpart.
Etymology. “Arm-out” marks the absence of the shoulder that would otherwise sit between the legs and the neck. That absence is the whole difference: nothing obstructs the strangle, so the escape hierarchy is compressed and the honest window is short.
Mechanics. Blocking the leg swing is the real defence, because once the triangle closes there is no shoulder to buy time. Head extension and an immediate exit follow if it lands, and a defender gets roughly one stack attempt before tapping is the correct decision.
Cross-reference. “Arm-in rear triangle escape” is the slower back triangle. Full escape coverage on Rear Triangle Escape.