Concentration Curl

The concentration curl is the most focused biceps movement there is: seated, you brace your elbow against the inside of your thigh and curl a single dumbbell up with a slow, deliberate squeeze. Anchoring the arm removes every trace of swing, so there's no way to cheat the rep — the biceps works in complete isolation, and that strict, concentrated contraction is what builds the peak of the muscle. Working one arm at a time also lets you give each side your full attention and even out any strength gap, and it asks for almost nothing: one dumbbell and a bench. It's the classic finisher, the movement you reach for to squeeze the last bit of work out of the biceps after your heavy curls are done. The things to watch are a loose wrist that can get strained under load and letting your form drift as you tire. Curl slowly, squeeze hard at the top, and lower under control. For sheer biceps focus, nothing beats it.