By lying down you are able to isolate the muscles of your biceps without standing or sitting.
Muscle group: Biceps
Attach a short bar to a cable pulley set on the lowest setting.
Lie down on a mat or the floor with your feet touching the weight stack.
Grasp the bar with and underhand grip (palms facing up).
With your arms fully extended and your elbows at your sides, pull the bar in an arc to your chest.
Pause for a moment contracting your biceps, and then return to the starting position.