Flexion of wrists with barbell in the back

Move the wrist or forearm without shifting the elbow or losing hand alignment. Control both directions, especially when resistance is used. 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 shoulders and forearms; match resistance and range to a intermediate level and never force a painful repetition.