Windshield Wipers is an advanced level core exercise. Lay on your back with your arms out to your side and your knees up so that they are perpendicular to the floor. Rotate your knees to one side using a comfortable range of motion then rotate over to the other side. Press your opposite hand down on the ground to keep your back on flat. To increase the intensity of the exercise you can extend your legs so that they are straight.
Core | Advanced | Rectus Abdominus (Abs), Obliques