Stir the Pot Exercise for Core Strength, Spinal Stability and Athletic Control Basic planks can be useful, but eventually many active adults need a greater challenge. The stir-the-pot exercise is an advanced core-stability drill performed with the forearms on a stability ball. Instead of holding completely still, you make controlled circles with the arms while the trunk resists movement. That combination increases the demand on the abdominal muscles, shoulders, hips, and spin