Supine Sideliner (or whatever you call it) Breakdown This movement, which has many names, is a great core workout that requires a high amount of body coordination. It starts with the initial hollow body roll, where we’re rocking back and forth with concave shoulders. Next, we need to be able to twist our legs one direction while twisting our arms in the opposite direction, rocking from one hip to the other. Once we have this down, we can use our hands on the floor to assist as we start moving to