Months before the 1975 Mr. Olympia contest, filmmakers George Butler and Robert Fiore persuaded Schwarzenegger to compete, in order to film his training in the bodybuilding documentary called Pumping Iron. Schwarzenegger had only three months to prepare for the competition, after losing significant weight to appear in the film Stay Hungry with Jeff Bridges. Lou Ferrigno proved not to be a threat, and a lighter-than-usual Schwarzenegger convincingly won the 1975 Mr. Olympia.

What was the name of the bodybuilding film Schwarzenegger starred in?