Start: Grab a barbell or EZ-curl bar with an underhand, shoulder-width grip, and lie on your chest on an incline bench set at 45 degrees. Hold the bar at arm's length below your shoulders.
Finish: Curl the bar up as high as you can without allowing your upper arms to move forward. Pause at the top and contract your biceps. Slowly return to the starting position.
Bend back your wrists so the heels of your hands lead the movement. This makes the exercise tougher on your biceps.