FORT DODGE, Iowa — It's a sport where punching, kicking and slamming a knee into someone's gut are allowed. And like it or not, its popularity has surged in recent years. Known on the street as cage fighting (search), extreme fighting or mixed martial arts, it features a combination of wrestling, boxing and jujitsu. The goal: Knock your opponent out cold ... or force him to surrender. "I don't think it's that violent. It's the same in football, baseball and basketball — they all get injured just as bad. It's just a sport," Fort Dodge, Iowa, cage fighter Donnie Nordstrom...