Time travel. The answer to how the early bodybuilders got access to these drugs is time travel. I mean, its obvious to anyone with even a modicum of intelligence, and by that I mean the mental ability needed to run basic non-voluntary bodily functions like respiration and heartbeat, that early bodybuilders were also time travelers. Simples.
So there we have it. All the proof needed to say for certain that Steve Reeves and his cohorts were in fact, on "stayroids". Time-fooking-travel.
FM, baby. FM.