Overview of MMA

Though rules have been adopted, there is no general sanctioning body for the sport, and the sets of rules vary according to the laws of individual organizations and localities. It was thought that Olympic recognition would be forthcoming for the 2004 Summer Olympics, held in Athens, under the banner of pankration. However, the International Olympic Committee was unconvinced that Greece could handle the total number of sports proposed. To placate the IOC, the organizers removed all new medal sports and pankration missed out.[5]
The techniques utilized in mixed martial arts competition generally fall into two categories: striking techniques (such as kicks, knees and punches) and grappling techniques (such as clinch holds, pinning holds, submission holds, sweeps, takedowns and throws). Some unarmed hand to hand combat techniques are considered illegal in most or all modern competition, such as biting, eye-gouging, fish-hooking and small joint manipulation.[6][7][8] Over the last ten years, strikes to the groin have become illegal in all sanctioned organizations.[6] The legality of other techniques such as elbows, headbutts and spinal locks vary according to competition or organization.
A victory in a bout is normally gained by the judges' decision after an allotted amount of time has elapsed, a stoppage by the referee or the fight doctor (in the event that the competitor is injured or can no longer defend himself intelligently), a submission, by a competitor's cornerman throwing in the towel, or by knockout.
While competition in the sport is occasionally depicted as brutal by the media,[9] there was no death or crippling injury in a sanctioned event in North America[10] until the death of Houston, Texas fighter Sam Vasquez on November 30, 2007.[11] Vasquez collapsed shortly after being knocked out in the third round of an October 20 fight at the Toyota Center in Houston by Vince Libardi.[12] Vasquez had two separate surgeries to remove blood clots from his brain, and shortly after the second operation suffered a major stroke and never regained consciousness.[11] The only other verified fatality in competition is the 1998 death of Douglas Dedge in an unsanctioned fight in Ukraine. There are unconfirmed reports that Dedge had a pre-existing medical condition.[13] Questions also have been asked about the health of Vasquez before his final bout, although no firm information has yet surfaced. Since he was age 35, he would have had to undergo extensive pre-fight medical screening in order to obtain a license to compete in Texas.[11]
A study by Johns Hopkins University concluded "The overall injury rate [excluding injury to the brain] in MMA competitions is now similar to other combat sports [involving striking], including boxing. Knockout rates are lower in MMA competitions than in boxing. This suggests a reduced risk of TBI in MMA competitions when compared to other events involving striking."[14]

Reference: http://en.wikipedia.org/wiki/Mixed_martial_arts