From September 1934:
There is no accounting for strange accidents. Take what happened to Clark Gable for example. Clark has hunted bears and lions in the most dangerous mountain-lands. He has enacted scores of hazardous stunts for movie cameras. Throughout these experiences, he has never been scathed.
But recently, working on a sequence for his new film, an unexpected noise behind him caused Gable to jerk his head around quickly. The twist sprained the muscles of his neck and shoulder, and the pain of the contracted muscles was so great that Clark was rushed to a hospital.