It is also used, but not formally named, in Judo[1] though it is sometimes referred to as dō-osae in Japanese, meaning "trunk hold".

Tsunetane Oda, a judo groundwork specialist who died in 1955,[3] demonstrated the technique on video.

In this guard the legs are hooked behind the back of the opponent, preventing them from standing up or moving away.

The position affords many options for the guard player to initiate techniques such as sweeps and submission holds.

The guard also allows one to elevate or set the opponent off balance and because of this it is particularly useful in avoiding damage and allows transitions to other dominant positions.

Likewise, skilled use of the x-guard can prevent the opponent from attempting a kick, or throw them off balance should they raise a leg.

The position was used by Brazilian Jiu-Jitsu practitioner Nino Schembri and popularized and made into a system by Eddie Bravo.

The 50-50 (Fifty-fifty) guard is a position popularized by Roberto “Gordo” Correa and extensively used by the Mendes Brothers, Rafael and Guilherme Mendes, Bruno Frazzato, Ryan Hall and Ramon Lemos from the Atos Jiu-Jitsu Team.

There are several ways of doing so; many involve pain compliance whereby the practitioner persuades the opponent to release their guard through an abrasive action.

Examples of this type of action would be digging the practitioner's forearms into the inner thigh of the opponent, standing and attempting a can opener neck crank, or in the case of a mixed martial arts setting, to simply strike the opponent until the guard is released.

Passing the guard however has perils of its own, as it has a tendency to leave the practitioner particularly vulnerable to counterattack in the form of sweeps and submissions.