I train with some world class powerlifters (WPO and IPA champs) and most have jacked bis/tries and do little if any iso work, and they def don't have "Arm Days". WTF I am not knocking anybody on here for how they train, but an arm day is like a day off. IF you want big arms do some heavy pressing and some heavy pulling. A 400 lb board press and some weighted chins will blow your arms up. Peace