Superman Does His Own Stunts
Superman having a costume that includes bulky muscles is nothing new, actually it originated back with George Reeves costume to make him look like he had some extra weight on him. The costume also probably helped pad any crash landings he might have had, as the guy did most of his own stunts on the show! He performed stunts like jumping from relativinly high heights, jumping off a springboard, and swinging through windows. Although, he did use a stunt man for some of his harder stunts, it was still pretty impressive to be able to carry out the stunts while being able to ensure hitting his mark to make the scenes look as realistic as possible.
