CARTHAGE, Mo. -- Ultimate fighting was once the sole domain of burly men who beat each other bloody in anything-goes brawls on pay-per-view TV.

But the sport often derided as "human cockfighting" is branching out.

The bare-knuckle fights are now attracting competitors as young as 6 whose parents treat the sport as casually as wrestling, Little League or soccer.

The changes were evident on a recent evening in southwest Missouri, where a team of several young boys and one girl grappled on gym mats in a converted garage.

Two members of the group called the "Garage Boys Fight Crew" touched their thin martial-arts gloves in a flash of sportsmanship before beginning a relentless exchange of sucker punches, body blows and swift kicks.

No blood was shed. And both competitors wore protective gear. But the bout reflected the decidedly younger face of ultimate fighting. The trend alarms medical experts and sports officials who worry that young bodies can't withstand the pounding.

Tommy Bloomer, father of two of the "Garage Boys," doesn't understand the fuss.