Iron Agers looove to post that pic of Ron taking air, just love what they think that means. Their beloved Iron Age BBs would've done same if the equipment had been available then. It's not essential, just a convenience after posing.
Arnold was bulky between contests earlier in his career, then later got very light between shows because he obviously couldn't stay big without the juice. It had a huge effect on him and he didn't anywhere near the same guy without it.