If it seems like “American Ninja Warrior” was just here,—that’s because the popular NBC show has never really left, with a plethora of “Ninja Warrior”-inspired gyms, contests and high-profile competitors calling Colorado home. The same goes for “American Ninja Warrior’s” Matt Iseman, a 46-year-old Denver native who visits frequently for work and family. As the longest-serving host of the eight-year-old show, Iseman has benefited from “American Ninja Warrior’s” impressive cultural momentum as the obstacle-course competition has spun off TV series (including USA Network’s “Team Ninja Warrior,” which Iseman also co-hosts) and countless home practitioners. Iseman, who won NBC’s “New Celebrity Apprentice” in February and has a Daytime Emmy to his credit for “Clean House,” returns next week for NBC’s FanFest.