Schwarzenegger has admitted to using performance-enhancing anabolic steroids while they were legal, writing in 1977 that "steroids were helpful to me in maintaining muscle size while on a strict diet in preparation for a contest. I did not use them for muscle growth, but rather for muscle maintenance when cutting up." He has called the drugs "tissue building."

In what year did Schwarzenegger write that he used anabolic steroid because they were "helpful"?