Once they allowed Lumpsford it opened the door to everyone else to use plastic of some sort.
At least I can't say
for sure Derek has PMMA in his lats or arms. It would be a hard sell saying Derek has it but for example Nick doesn't, or in fact any of the other guys. Derek looks smooth all over but the shape of his arms and lats is natural enough to me.
The woman I believe has used it based on visuals.
In the 90s they allowed some totally absurd looks, Nasser, Ruhl, Ernie Taylor, Dexter Jackson's calves, Ferrigno's implants. Flex Wheeler had absurd amounts of oil, calves looked absolutely mangled, like utter shit. Today everyone thinks those were the glory days, Flex the
Sultan of oil Symmetry. I don't know why many think the sport went to shit only recently.