This weekend, asfaces off in a boxing match against undefeated , he'll have many young fans of mixed martial arts rooting for him.
The popularity of MMA has been growing for years worldwide, and lately more kids are getting in on the action — despite the concerns of some parents and pediatricians. More than 3.5 million Americans of all ages participate in MMA for fitness or competition.
Fifteen-year-old Korey Mendoza says he took it up it after he'd been bullied.
"it's just good to learn how to defend yourself and know what to do," he told CBS News' Danielle Nottingham at the gym where he trains in San Bernardino, California.
Korey's father, Sam Mendoza, supports his son's involvement and has seen the sport's popularity surge.
"When we first started and would go to tournaments maybe there would be 100 kids, and now in the database we probably have about 600 or 700 looking for fights actively," he said.
was the inspiration for Kaylee Bramlette, a 13-year-old girl who trains at the same gym.
"It teaches me self-defense," said Kaylee, adding that the toughest part of MMA for her was "probably [to] get the courage to stand up and say you'll do it."
When young fighters like Kaylee or Korey get into the cage, special rules apply. They are not allowed to strike their opponent's head or go for the knockout. And a doctor exams each fighter before and after every competition.
While there's not a lot of data on the dangers of the sport for children, pediatricians like Dr. John Tierney say possibleare a big concern.
"We're always concerned about the growing brain and what damages that might have with a single injury or the accumulation of multiple injuries," Tierney said.
The American Academy of Pediatrics actually warns against children having excessive media exposure to MMA contests, since they might get hurt if they imitate what they see.
Proper coaching and adhering to safety rules can help reduce the risk, and enthusiasts like Korey Mendoza think it's worth it.
"It helped me make friends and be more confident around other people," he said.