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. Quadriceps The quadriceps (quads) are a group of four muscles on the front of the thigh. They allow your knee to straighten and provide stability when standing. Your quads are the most important muscle group for maintaining the ability to stand and to walk independently. Exercise Instructions Step 1 Stand on the Bosu with a slight bend in your knees and your feet pointing forward. With dumbells in hand, resting on your thighs, slowly raise them to the front of the body up to shoulder level. Step 2 Lower the dumbbells back down to your thighs then move them over to your sides on you hips and raise them outwards to shoulder level. Step 3 Lower the dumbells back down to your sides, slide them to the front of your body again and repeat the action.