STARTING POSITION:
You need to place a bench in front of the pulley. Select the appropriate resistance in the weight stack. There should be a bar that is attached to a pulley in its highest position. Grab it with a supinated grip and lay down on the bench. Place your feet on the bench. Your arms should be extended and the cable should have tension.
MOVEMENT:
Contracting your biceps, fully bend your elbows while you exhale. Make sure you only move the forearms. Return to the starting position in a smooth movement while you inhale. The moving weights should not touch the rest of the stack.
TIPS: The exercise key is quality over quantity. The trick is to perform the exercise using proper form.