Mike Gullett / AP

Skyler Bloomer, 11, does chin-ups during a training session at Garage Boys Fight Crew in Carthage, Mo, on March 5. Bloomer and several other kids are training to compete in ultimate fighting tournaments.

“If they get in trouble or get bad grades, I’ll hear about it and they can’t come to training,” he added.

In most states, mixed martial arts is overseen by boxing commissions. In Missouri, the Office of Athletics regulates the professional fights but not the amateur events, which include the youth bouts. For amateurs, the regulation is done by sanctioning bodies that have to register with the athletics office.

The rules are different in Oklahoma, where unauthorized fights are generally a misdemeanor offense. The penalty is a maximum 30 days in jail and a fine up to $1,000.

Joe Miller, administrator of the Oklahoma Professional Boxing Commission, said youth fights are banned in his state, and he wants it to stay that way.

“There’s too much potential for damage to growing joints,” he said.

Miller said mixed martial arts uses a lot of arm and leg twisting to force opponents into submission. Those moves, he said, pressure joints in a way not found in sanctioned sports like youth boxing or wrestling.

But Nathan Orand, a martial arts trainer from Tulsa, Okla., said kids are capable of avoiding injuries, especially with watchful referees in the rings. He thinks the sport is bound to grow.

“I can see their point because when you say ’cage fighting,’ that right there just sounds like kids shouldn’t be doing it,” Orand said.

“But you still have all the respect that regular martial arts teach you. And it’s really the only true way for youth to be able to defend themselves.”

Back in the Carthage garage, Bloomer said parents shouldn’t worry about kids becoming aggressive from learning mixed martial arts. He said his older son was picked on by bullies at school repeatedly last year but never fought them, instead reporting the problem to his teachers.

And fighters including his 8-year-old son get along once a bout is over, Bloomer said.

“When they get out of the cage, they go back and play video games together. It doesn’t matter who won and who lost. They’re still little buddies.”