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. Hamstrings The hamstrings play a crucial role in many daily activities, such as, running, jumping, walking and cycling. Strengthening your hamstring muscles help to protect your knees from injury by absorbing the stress placed on the knee. Weak hamstrings can lead to knee injury. 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 Stand on top of the upside down Bosu with your foot placed right in the center. Step 2 Bend forward holding a slight bend in your knee and lower the dumbbell to the tip of the Bosu. Step 3 Stand back up through the back of your leg and press the dumbbell over your head.