Grab an EZ-bar using a shoulder width and palms down (pronated) grip.
Now place the upper part of both arms on top of the preacher bench and have your arms extended. This will be your starting position.
As you exhale, use the biceps to curl the weight up until your biceps are fully contracted and the barbell is at shoulder height. Squeeze the biceps hard for a second at the contracted position.
As you breathe in, slowly lower the barbell until your upper arms are extended and the biceps is fully stretched.