Biceps curl with barbell prone on an incline bench

Flex the elbow without letting the shoulder drift forward or the torso swing. Lower the load under control until the starting position is restored. Use a steady tempo: control the return phase in particular and avoid relying on momentum. Exhale through the hardest part and inhale as you recover the starting position.

Check that the movement stays stable in both directions and that the torso is not compensating. The goal is controlled loading of biceps and forearms; match resistance and range to a intermediate level and never force a painful repetition. Make sure the bench is stable and that the shoulders, pelvis or feet do not shift during the set.