It's hard to learn how to fight until you've actually stepped into the ring, which is why the expertise of professional fighters is so highly valued in instructors at martial-arts clubs. With teachers whose in-the-ring careers earned them nicknames like "Merciless" and "Little Giant," American Combat Club's crew members turns their own grappling and striking experiences into a lineup of mixed-martial-arts classes fit for all levels. They teach a fusion form of boxing and kickboxing that incorporates elbow and knee strikes, as well as a Brazilian-jujitsu-based grappling program that elucidates takedowns, submissions, and defenses against commonly encountered holds. Becoming a well-rounded fighter requires more than just technical skill, however, so the teachers also offer full-body conditioning classes in which participants flip tractor tires, swing sledgehammers, and heft medicine balls until they finally confess that they can't actually cure the common cold.