Seated Alternating Dumbbell Curl with Rotation

The seated alternating dumbbell curl is a biceps isolation exercise performed one arm at a time from a bench, with the forearm rotating as each dumbbell travels up toward the shoulder. That twist matters: the biceps brachii both bends the elbow and turns the palm up, so rotating under load recruits it more completely than a locked grip does. Sitting removes the hip drive that creeps into standing curls, which is why coaches program it when a lifter keeps cheating reps. Alternating arms also doubles the rest each side gets between reps, letting you hold cleaner form deeper into a set. Pause for a full second at the top, where tension peaks, and lower for two to three seconds. Sets of ten to twelve reps per arm, with a weight you could curl fourteen times, build both size and definition in the upper arm.