Sit on a preacher bench with your chest against the support pad and your feet flat on the floor. Hold a dumbbell in each hand with an underhand grip (palms facing up).
Extend your arms fully over the preacher bench pad, allowing the dumbbells to hang down in front of you.
Curl the dumbbells upward towards your shoulders by bending your elbows, keeping your upper arms stationary against the pad.
Squeeze your biceps at the top of the movement, then slowly lower the dumbbells back to the starting position. Repeat for the desired number of repetitions.
Form tips
Keep your upper arms pressed against the pad to isolate the biceps.
Ensure your wrists remain straight and aligned with your forearms.
Avoid locking your elbows at the bottom of the movement.