MUSCLES ENGAGED Shoulders The shoulder is the most movable joint in the body. However, it is an unstable joint because of the range of motion allowed. This instability increases the likelihood of joint injury, often leading to a degenerative process in which tissues break down and no longer function well. 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. Equipment Used Bosu The BOSU balance trainer stands for "Both Sides Utilized" and is most often used for balance training, various athletic drills and aerobic activities. Exercise Instructions Step 1 Start on top of the Bosu with your feet slightly narrower than shoulder width, a soft bend in your knees and most of your body weight on your heels. Hold the weight plate in both hands just off of your thighs. Step 2 Raise the weight plate up to the same height as your forehead making sure that you keep your core engaged and your knees bent. Step 3 Lower the weight plate back down to the starting position maintaining proper form throughout the entire range of motion.