MUSCLES ENGAGED Chest Strengthening the chest muscles will help you push things easily and effortlessly. The muscles in your chest help stabilize your shoulder joint, which reduces your vulnerability shoulder joint injuries. Working your chest muscles also has an aesthetic factor (body contouring). 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. Exercise Instructions Step 1 Start in a push-up position with your hands under your shoulders and your lower back flat. Step 2 Lower yourself down to the bottom of a push-up and then press out as explosively as you can so your hands come off the ground at full extension. Step 3 Place your hands back on the ground softly and repeat.