Russian hook
A Russian hook is a punch, used in Russian combat sports, which resembles a traditional boxing hook yet keeping the puncher's thumb towards the floor. Its name is a Japanese wasei-eigo, Russian hook, coined by Satoru Sayama due to its association with mixed [martial arts in Japan], where it was popularized by Igor Vovchanchyn and Fedor Emelianenko. In karate it is classified as an inverted strike or uraken and called furi uchi or mawashi uchi.
Technique
The Russian hook or mawashi uchi is superficially similar to a regular boxing hook, but unlike most boxing punches, it disregards hip and body movement and instead capitalizes on rotation of the shoulder and arm. While doing it, the puncher internally rotates his punching hand so the thumb points down to the floor and follows a trajectory around a vertical axis, hitting the opponent with the knuckles of an upside down hand. Some sources consider it less of a punch than a forward-facing backfist, liable to be found illegal in orthodox boxing. In karate it is used often to travel around the opponent's head and strike its back.It is considered a complicated and situational technique, which becomes more useful in rulesets combining both striking and grappling. Throwing the hook minimizes leg movement and positioning, making it easier to respond to a takedown attempt, and eases the transition to grappling after impact. The technique also allows the user to extend his arm and range almost as much as a straight, and simultaneously raises the shoulder of the punching arm up to cover the chin. However, improper contact increases the risk of hand injuries compared to other punches.