With this exercise your lay face down to isolate your biceps.
Lay face down on a high bench with your head at one end and your toes pressed against the floor to support you.
Grasp a barbell with palms facing up, about 12 inches apart.
Extending your arms to the floor, curl your arms back towards your head in a slight arc, so your biceps touch your forearm.
Slowly return to the starting position.