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. Equipment Used Medicine Ball A medicine ball (also known as an exercise ball, med ball, or fitness ball) is a weighted ball roughly the diameter of the shoulders (approx. 14 inches). Medicine balls come in a variety of weights from 2lbs. to 30lbs. and can be made of hard plastic, dense rubber or synthetic leather material. Exercise Instructions Step 1 Start in a seated position on the Bosu with your tailbone centered right in the middle. While keeping your back straight and your knees bent, tilt your body backwards until your feet lift off of the floor. Step 2 With the medicine ball in both hands, twists from hip to hip, keeping your feet off of the floor the entire time. Step 3 Continue for the recommended number of reps or length and time maintaining proper form throughout the entire exercise.