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. Equipment Used Dumbbells The dumbbell, a type of free weight, is a piece of equipment used in weight training. It can be used individually or in pairs (one for each hand). Dumbbells vary in weight from 3lbs. up to 150lbs. 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 in a standing position on top of the Bosu. Step 2 Hold the dumbbells at your shoulders and press them overhead one at a time. Step 3 Alternate between each side for the recommended number of reps.