A Bicep Built for Two(1955)

From Press Kit: Katnip's serenading of a girl cat is interrupted by a tough cat that runs him off and takes over.The love-lorn Katnip is determined to best the muscle-bound cat and enlists the aid of Herman. Herman, with bad-intentions, puts Katnip through a muscle-building course which consists of weight-lifting, bar-chinning and equipment rigged with high explosives.