NEW YORK (Reuters Health) - The rate of serious head injuries among professional mixed martial arts competitors is potentially twice that of professional football players, according to U.S. researchers.
With the sport growing in popularity, especially among youth, new rules may be needed to protect kids and professionals alike from repeated traumatic brain injuries, a new study concludes.
"When people compare mixed martial arts to other sports, we need to take into account the risk of persistent effects down the line," said Michael Hutchison, a researcher at the University of Toronto who led the work.
The popularity of mixed martial arts, which combines techniques and skills from a variety of fight disciplines including judo, karate and kickboxing, has exploded around the globe in recent years. Professional mixed martial arts matches are now legal in all states but New York.
Yet players' risk of head injury hadn't been well studied, according to Hutchison and his coauthors. The highly physical nature of the contact sport - which some critics consider dangerous or violent - got the researchers wondering just how high a risk players run of getting knocked out repeatedly.
"The fighting seen on TV was what piqued our interest, given how public mixed martial arts has been and the interest that's been generated over the past few years," Hutchison told Reuters Health.
"What you see is one thing, but how can we quantify injuries that happen, and what are the mechanisms and characteristics important from a brain injury and prevention perspective?" he said.
The team investigated by watching video recordings of 844 professional mixed martial arts matches sponsored by the Ultimate Fighting Championship - the most prominent mixed martial arts promoter worldwide - to count two types of events.
The first event they looked for was knock-outs, in which players are literally knocked unconscious. The second, known as technical knockouts, occur when a referee or other authority judges that the player is too woozy to successfully defend him- or herself. Both kinds of knockout end the match.
The researchers also used statistics to investigate which factors were associated with a player having a higher risk of a knockout or a technical knockout due to being struck multiple times.
They found that players suffered a knockout in 12.7 percent of matches, and that a technical knockout took place in about 19 percent, meaning that nearly one-third of matches ended as a result of some type of head trauma.
These numbers mean that out of every 100 matches in which a mixed martial arts athlete could be knocked out, known as an athlete exposure, the injury would happen 6.4 times.
The comparable concussion rates for boxing and kickboxing are, respectively, 4.9 and 1.9 per 100 exposures, the authors note.
It's probably safe to consider a knockout equivalent to a concussion, since any head injury that causes unconsciousness usually includes a concussion, the team writes in the American Journal of Sports Medicine.
Technical knockouts are harder to characterize, but the state of woozy helplessness that causes a referee to stop the match is certainly similar to concussion symptoms, the researchers point out.
Moreover, they observed that competitors often used the few seconds before the referee stepped in to repeatedly kick the downed opponent in the head.
If all knockouts and technical knockouts are counted as concussions, the rate among professional mixed martial arts athletes seen in the study was about 16 per 100 athlete exposures.
It's tempting to compare those statistics to rates of concussions in sports such as football, which has been found to have 8.08 concussions per 100 plays, and ice hockey, with 2.2 concussions per 100 athlete-encounters.
Yet the research team hesitates to generalize that far because of the uncertainty over how many technical knockouts really included concussions.
"Is this more dangerous than other sports? We really are not quite there yet, because it's one thing to look at how likely an event (such as a knockout) is to happen, and another to look at how long the effects will last," Hutchison said.
Nonetheless, they suggest that all children be banned from participating in the sport, noting that medical associations in the U.S., Canada and Australia have made the same recommendation.
Rule changes that encourage referees to step in more quickly and train them to recognize the symptoms of concussions, might also help to protect professional competitors from the long term damage of repeated brain injuries, the researchers say.
SOURCE: bit.ly/1id8j2O American Journal of Sports Medicine, online March 21, 2014.