Muscle Group: Forearms
Rope twists specifically target the brachioradialis. This is the most prominent of the forearm muscles. When the palm is down, the brachioradialis is the muscle that dramatically pops up and over your elbow joint.
Attach a rope attachment to a low cable pulley. Now hold the rope with your forearm resting on your thigh in a hammer position. With your wrist flexed upward, twist the weight as far to the right as you can and then as far back to the left as you can.
This is an easy exercise to superset with bicep rope movements.