Starting Position: Begin lying on your back with your legs in the 90/90 position as shown, core engaged. Movement: Press your low back into the floor to engage your core. Straighten one leg towards the ceiling. While maintaining your core slowly lower your leg until your heel is about an inch off the floor. Then bend your knee back to the 90/90 position. You may perform this with a straight leg, or with both legs at the same time for a greater challenge.