MUSCLES ENGAGED Abdominals The abdominal muscles (abs) provide movement and support to your core area. The deeper and closer to the spine the particular abdominal muscle is, the more effect over body posture it will have, and this often contributes significantly to a healthy back. Exercise Instructions Step 1 Start on your back with both legs in the air and your hands placed at the side of your body. Step 2 Lift your hips off the floor and drive your feet straight up towards the ceiling by contracting your upper abs. Step 3 Lower your body back down until your tailbone softy touches the floor and repeat.