If you have a low cable pulley with a rope attachment available in your gym, the rope curl is an effective exercise for targeting the arm flexor muscles. Similar to the dumbbell hammer curl, the rope curl involves the flexion of the arm using a neutral (palms facing each other) grip, which results in greater activity of the brachioradialis and brachialis compared to the biceps.
The brachioradialis is a muscle which runs from the forearm to the upper arm, thus making the rope curl a good forearm exercise in itself. The brachialis is a muscle which runs beneath the biceps, and is also responsible for the flexion of the elbow joint. As said, these two play a greater role in the rope curl compared to the biceps, which are more active during traditional barbell, dumbbell and EZ bar curls where a supinated (palms facing up) grip is used.
Due to using a low cable pulley, the rope curl can also be performed lying down. This can not only be useful for athletes who wish to use stricter form, but is also a great option for those with back issues or other injuries which make the standing version not feasible.