The hanging windshield wiper is an advanced abdominal training exercise that is also extremely challenging to other muscles of the upper body, including the lats (latissimus dorsi), biceps, and grip. It requires—and builds—great strength in the rectus abdominis or "six-pack" muscles, as well as the obliques and deep core muscles. If you can't perform it hanging from a bar, the lying windshield wiper on the floor provides some of the same benefits.