Knockout

right|200px|thumb|[[Ingemar Johansson knocks Floyd Patterson out, becoming boxing heavyweight champion of the world, on June 26, 1959.]]

right|200px|thumb|A heavy blow to the head is a frequent cause of a knockout. [[Muhammad Ali delivers one to Brian London and retains his heavyweight championship by third-round KO on August 6, 1966.]]

A knockout (abbreviated to KO or K.O.) is a fight-ending, winning criterion in several full-contact combat sports, such as boxing, kickboxing, Muay Thai, mixed martial arts, karate, some forms of taekwondo and other sports involving striking, as well as fighting-based video games. A full knockout is considered any legal strike or combination thereof that renders an opponent unable to continue fighting.

The term is often associated with a sudden traumatic loss of consciousness caused by a physical blow. Single powerful blows to the head (particularly the jawline and temple) can produce a cerebral concussion or a carotid sinus reflex with syncope and cause a sudden, dramatic KO. Body blows, particularly the liver punch, can cause progressive, debilitating pain that can also result in a KO.

In boxing and kickboxing, a knockout is usually awarded when one participant falls to the canvas and is unable to rise to their feet within a specified period of time, typically because of exhaustion, pain, disorientation, or unconsciousness. For example, if a boxer is knocked down and is unable to continue the fight within a ten-second count, they are counted as having been knocked out and their opponent is awarded the KO victory.

In mixed martial arts (MMA) competitions, no time count is given after a knockdown, as the sport allows submission grappling as well as ground and pound. If a fighter loses consciousness ("goes limp") as a result of legal strikes, it is declared a KO. Even if the fighter loses consciousness for a brief moment and wakes up again to continue to fight, the fight may be stopped and a KO declared. As many MMA fights can take place on the mat rather than standing, it is possible to score a KO via ground and pound, a common victory for grapplers.

In fighting games such as Street Fighter and Tekken, a player scores a knockout by fully depleting the opponent's health bar, with the victor being awarded the round. The player who wins the most rounds, either by scoring the most knockouts or by having more vitality remaining when time expires during each round, wins the match. In some fighting games like Soul Calibur as well as platform fighters like Super Smash Bros, the player can also score a KO when the opponent falls off the fighting area. This differs from combat sports in reality, where a knockout ends the match immediately. However, some fighting games aim for a more realistic experience, with titles like Fight Night adhering to the rules of professional boxing, although technically they are classified as sports games, and share many of the same features as NFL and NBA video games.

Technical knockout<span class="anchor" id="Technical knockout"></span>

right|250px|thumb|The referee may stop a match if they deem either competitor unable to fight.

A technical knockout (TKO or T.K.O.), stoppage, or referee stopped contest (RSC) is declared when the referee decides during a round that a fighter cannot safely continue the match for any reason. Certain sanctioning bodies also allow the official attending physician at ringside to stop the fight as well. In amateur boxing, and in many regions professionally, including championship fights sanctioned by the World Boxing Association (WBA), a TKO is declared when a fighter is knocked down three times in one round (called an "automatic knockout" in WBA rules). Furthermore, in amateur boxing, a boxer automatically wins by TKO if his opponent is knocked down four times in an entire match.

In MMA bouts, the referee may declare a TKO if a fighter cannot intelligently defend themselves while being repeatedly struck. and over time have been linked to permanent neurodegenerative diseases such as chronic traumatic encephalopathy ("punch-drunk syndrome"). Because of this, many physicians advise against sports involving knockouts.

Knockdown

thumb|right|275px|A boxer has been knocked out and is being inspected by a ring doctor.

A knockdown occurs when a fighter touches the floor of the ring with any part of the body other than the feet following a hit, but is able to rise back up and continue fighting. The term is also used if the fighter is hanging on to the ropes, caught between the ropes, or is hanging over the ropes and is unable to fall to the floor and cannot protect himself. A knockdown triggers a count by the referee (normally to 10); if the fighter fails the count, then the fight is ended as a KO.

A flash knockdown is a knockdown in which the fighter hits the canvas but is not noticeably hurt or affected.

Archie Moore 132
James Red Herring 58
Eric Esch 58
Tony Galento 57
John Henry Lewis 57
Pascual Perez 57
Charley White 57
Kid Williams 57
Len Harvey 57
Jose Luis Castillo 57
Bob Fitzsimmons 57
Tiger Flowers 56
Georges Carpentier 56
Pedro Montanez 56
Irish Bob Murphy 56
Charles Kid McCoy 55
Dixie Kid 55
Gorilla Jones 55
Freddie Mills 55
Manuel Ortiz 54
Marcel Thil 54
Solly Krieger 54
Jose Napoles 54
Bennie Briscoe 53
Obie Walker 53
Peter Kane 53
Wladimir Klitschko 53
Shannon Briggs 53
Eugene Criqui 53
Joe Louis 52
Mike McTigue 52
Philadelphia Jack O'Brien 52
Lew Jenkins 52
Marvin Hagler 52
Rocky Graziano 52
Ezzard Charles 52
Arturo Godoy 52
Kid Chocolate 51
Packey McFarland 51
Jimmy Slattery 51
Abe Attell 51
Miguel Angel Castellini 51
Jorge Vaca 51
Jorge Paez 51
Marco Antonio Rubio 51
Charley Burley 50
Jose Legra 50
Eder Jofre 50
Muhammad Ali 49

Technical knockout<span class="anchor" id="Technical knockout"></span>

Knockdown

See also

References