With efforts to legalize mixed martial arts still stalled in New York, a new Canadian study says the sport has a higher rate of concussions and other match-ending head trauma than football, hockey or boxing.
New York's Senate has proposed making professional MMA legal and regulating the sport.
Backers say it's already widely seen on television and practiced in gyms around the state, including unregulated amateur competitions.
They call the new study flawed and note ongoing research in Cleveland examining active and retired fighters' brain health.
The University of Toronto study examined records and videos from 844 professional bouts.
Researchers found nearly 13 percent ended in knockouts, while 21 percent ended in technical knockouts, usually after a combatant was hit in the head approximately 10 times shortly before the referee stopped it.