Start: You'll need a rolled-up workout towel for this one. Attach a stirrup handle to the low pulley, grab the handle with your nondominant hand, and kneel sideways to the cable column so your dominant side is toward the weight stack. Bend your nondominant arm 90 degrees so the elbow braces the towel against your hip. Your forearm should be parallel to the floor, in front of your abdomen.
Finish: Pull the handle out and away from your torso, keeping the towel pinned against your hip with your elbow, as if you were opening a door. Pause when your forearm is as far to the side as it will go, then return to the starting position. Finish the set with that arm, then switch and repeat with your other arm.