Frank originally came to prominence in 1993 portraying the Green Ranger, a villain who eventually became a hero and was later known as the White Ranger. Overall, between various reboots of the TV show and movies, Frank appeared 200 times as a Power Ranger, more than any other actor.
Frank frequently displayed his martial arts abilities on the show, skills he began developing at the age of 4, initially training in karate under noted Southern California instructor Louis D. Casamassa and his son, sport karate champion Chris Casamassa. He would go on to study a number of other martial arts before creating his own system, dubbed "Toso Kune Do," and opening several karate schools in California and Texas.
Frank debuted in mixed martial arts in 2010 at the age of 36. He went 4-0 as an amateur and 1-0 as a professional winning all his bouts in the first round, though there were allegations the matches were fixed.