:''KO redirects here. For other uses, see [[Ko]]. For other uses of knockout, see [[Knockout (disambiguation)]].''
'''Knockout''' (also referred to as a '''K.O.''' or '''knock'''), is a winning criterion in several [[full-contact]] [[combat sport]]s, such as [[boxing]], [[kickboxing]], [[Muay Thai]], [[mixed martial arts]] and others sports involving [[strike (attack)|striking]].[[Image:Box24-knock-down.jpg|thumb|250px|A boxer is knocked down and receives the 10-count.]] A knockout is usually awarded when one participant is unable to rise from the [[canvas]] within a specified period of time, typically because of fatigue, injury (serious or otherwise incapacitating, e.g. a bleeding cut above the eye can blind a fighter), loss of balance or [[unconsciousness]].

==Physical characteristics==
[[Image:Knock out.jpg|thumb|275px|A Cambodian [[Pradal Serey]] kickboxer is still knocked down while his adversary is being proclaimed the winner]]
There is actually very little known about what exactly causes a knockout but many agree it has to do with minor trauma to the brain stem. This usually happens when the head rotates sharply, often caused by a strike. A common misconception is a knockout is caused by compression put on the carotid arteries in the neck restricting blood flow, but this is in fact how a choke out works. <ref> Margaret Goodman, MD  [http://www.secondsout.com/RINGSIDE/sopranos.cfm?ccs=354&cs=9809 Ringside and training principles] URL last accessed [[June 20]] [[2006]]</ref> A basic principle of boxing is to defend against this vulnerability by keeping both hands raised about the face.

If a fighter suffers a [[concussion]] and becomes unconscious from a [[strike (attack)|strike]] with sufficient [[knockout power]], he or she is referred to as having been ''knocked out'' or ''kayoed'' (''KO'd''). Losing balance without losing consciousness is referred to as being ''knocked down'' ("down but not out"). Repeated blows to the head are known to gradually cause permanent [[brain damage]], with [[Alzheimer]]-like symptoms, and in severe cases may cause [[strokes]] or [[paralysis]]. Because of this, many [[physicians]] advise against sports involving knockouts.<ref>Lieberman, Abraham. [http://www.liebermanparkinsonclinic.com/content/view/48/31/ Causing Parkinson: Boxing, Brain Injury]. ''www.liebermanparkinsonclinic.com''. URL last accessed [[March 4]] [[2006]].</ref>

==As a winning outcome==
[[Image:SingletonBox-knockout.jpg|thumb|right|250px|A knockout can be characterized by temporary unconsciousness.]]
In [[boxing]], a knockout occurs when a fighter is knocked down and does not get up within 10 seconds, as counted by the referee.

===Technical knockouts===
A '''technical knockout''' ('''T.K.O.''') is often declared when the referee or other judges (such as official ring [[physician]], the fighter him or herself, or the fighter's [[cornerman|cornermen]]) decide that a fighter cannot continue the match, even though he did not fail the count.<ref>Sugar, Bert. [http://www.owingsmillsboxingclub.com/boxing.htm Boxing]. ''www.owingsmillsboxingclub.com''.  URL last accessed [[March 4]] [[2006]].</ref> [[United Kingdom|British]] records refer to TKOs as either "retired", if the fighter refuses to continue, or "R.S.F.", for Referee Stopped Fight.

==In mixed martial arts==
In [[mixed martial arts]], the definitions of knockouts and technical knockouts vary according to organization and jurisdiction. According to its publicized rules, the Japanese [[PRIDE FC]] promotion does not declare 'knockout' as an official type of victory, but rather only technical knockouts when the referee considers a fighter unable to continue<ref>PRIDE FC official website. [http://www.pridefc.com/pride2004/about/rules.htm Pride Rules]. ''www.pridefc.com''. URL last accessed [[March 4]] [[2006]].</ref>. Under New Jersey's ''Unified Rules of Mixed Martial Arts'', which has become the ''de facto'' standard of MMA rules in the United States, a knockout is defined as a "failure to rise from the canvas"<ref>New Jersey State Athletic Control Board. [http://www.state.nj.us/lps/sacb/docs/martial.htm Mixed Martial Arts Unified Rules of Conduct Additional Mixed Martial Arts Rules]. ''www.state.nj.us''. URL last accessed [[March 18]] [[2006]].</ref>. In [[Pancrase]], a knockout is declared when the competitor loses consciousness, and a technical knockout when the referee or judges consider a fighter unable to continue the match<ref>Pancrase Hybrid Wrestling official website. [http://www.pancrase.co.jp/en/rules/index.html#010 Pancrase official rules -2005 Edition-]. ''www.pancrase.co.jp''. URL last accessed [[March 4]] [[2006]].</ref>.

==References==
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[[Category:Martial arts terms]]
[[Category:Boxing terms]]

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[[he:נוקאוט]]
[[ja:ノックアウト]]
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