MUSCLES ENGAGED 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. 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 by lying on your back with your knees up at a 90 degree angle and your arms spread out to the sides. Step 2 Keeping your back pressed against the floor, sway your knees to the side until your bottom leg is about to touch the ground. Step 3 Lift your legs back up to the starting position, keeping your knees at a 90 degree angle.