DAVID LE/Staff photo. 8/21/15. Vince Klapper, Head Coach at Gymja, an American Ninja Warrior inspired facility inside Danvers Indoor Sports, helps eleven-year-old Max Vanderwilden, of Hamilton, swing from rings to a pole. Klapper and the other "Sensei's" teach kids how to maneuver their way through obstacle courses inspired by the hit show which Klapper has participated on.