Holly Hunter never played sports growing up, so portraying tennis star Billie Jean King showed her how it felt to be an athlete.
"We haven't seen too many women athletes portrayed on film," she said. "I thought, what a great opportunity to use my whole body."
Hunter said she was exhausted a month into her four months of training for "When Billie Beat Bobby," airing April 16 on ABC.
"Then I kind of broke through that and started feeling I was in the best shape of my life," she said. "That was intoxicating, to feel capable."
Hunter learned to play tennis and drilled five days a week with 1974 Wimbledon doubles champion Peggy Michel.
"When I did 'The Piano,' people asked me if I learned to play the piano for the movie," she said. "Tennis is like a musical instrument. It's not something you can pick up and be proficient in four months. You can only reach a certain level through an investment of some serious time."