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 your feet together and your heels tucked up towards your butt. Step 2 Curl back and touch your shoulder blades and your arms to the floor behind you. Step 3 Curl back up ad touch in front of your feet making sure your shoulder passes your hip.