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. Exercise Instructions Step 1 Start in a standing position while holding a dumbbell in each hand. Step 2 Place the dumbbells on the floor, jump out into a plank position and perform a push-up. Step 3 Jump back up to the starting position and press both dumbbells overhead.