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. Obliques Many people put a lot of focus on working their abs but forget their surrounding neighbors; the oblique muscles. Obliques serve as stabilizers, and are used in almost every physical activity. Exercising your obliques should be a very important part of your workout program. Exercise Instructions Step 1 Start in a plank position with your back flat and your core engaged. Step 2 Lift your leg up, over and tap it on the floor. Step 3 Alternate legs for the recommended number of repetitions.