Step aside, CrossFit. When it comes to extreme workouts, the undisputed champion is mixed martial arts training. What other fitness program has you learning how to wrestle another person to the ground or executing an arm bar like an ultimate fighter? A fast-growing combat sport popularized by professionals, mixed martial arts training is catching on with non-warriors who want that fighter's body without the pain and blood. You can get in fighting shape locally at the Academy in Brooklyn Center, Elements Boxing & Fitness in St. Paul or at Life Time Fitness Centers in Chanhassen and Lakeville. Compared to other extreme workouts, this one's a real knockout.