MUSCLES ENGAGED 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. 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. Equipment Used Plyometric Box Plyometric Boxes increase athletic ability concerning quick movements and explosiveness. They come in a variety of different heights (12"-48") and are usually made of metal or wood. Exercise Instructions Step 1 Stand in front of the box with your feet about shoulder width apart. Step 2 Perform a burpee and make sure that your chest and thighs make contact with the floor. Step 3 Jump up on the box and fully extend your hips and knees at the top.