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 Barbell A barbell is a piece of exercise equipment used in weight training, weightlifting and powerlifting. Barbells range in length from 4 feet (1.2 m) to 8 feet (2.4 m) and vary in diameter. Exercise Instructions Step 1 Hold the barbell on your chest with your hands just a bit wider than your shoulders. Your feet shoulder be hip width, your knees locked, your quads and glutes flexed and core engaged. Step 2 Press the barbell directly overhead. Step 3 Lower the barbell back to your chest and press back up again without bending your knees or hip.