^^ It was either teens or early 20's.
I've seen this one before. Someone pointed out that Arnie used to powerlift and weighltift. All those big pump sessions he used to do were mainly pre-contest. The rest of the year he did all sorts of things. Apparently he had a pretty decent C&J, and there was a cut scene from Raw Deal where he did a C&J.
I can't find the pic but he also used to participate in some strongman-like events in Munich. There's a pic from his "Education of a Bodybuilder" bio of him pulling a giant stone.