I get the biggest front shoulder pump from biceps curls. I hate it. Even when I do DB curls on a recline bench. Even when I use an arm blaster belt. Even when I do preacher curls, which I don’t like, because all the tension runs out in the top half of the movement (and coincidentally all the frat boys only do the top half of this movement). We have one machine at my gym where your arms go on a horizontal preacher bench and you do curls (it’s a machine, remember, so the fact that this wouldn’t work with free weights due to gravity doesn’t come into play), and if I use that, and I consciously push DOWN with my elbows as hard as I can, I can sometimes keep my front delts out of it. Think of this as the same principle as Janda situps, but for biceps. By actively flexing my rear delts, it should force my front delts to relax.
Now, I know that front delts are supposed to come into play a bit in biceps curls, but when I finish a set (with strict form, no less), and I have a huge delt pump and my arms are tiny and look like toothpics stuck in an orange (the arm coming out of the shoulder), I get p.issed.
I must have really messed up neural pathways or something.
Then again, I get a huge front delt pump from flat bench, too. And squats. And situps. That’s why I have big ass strong shoulders and I never do shoulder movements.