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. Equipment Used Wooden Dowel A wooden dowel is a solid cylindrical rod made of wood and is used for a variety of mobility drills. Exercise Instructions Step 1 Hold the dowel in both hands as close as you can but still being able to keep your elbows locked out during the entire range of motion. Step 2 Circle the dowel around your head rubbing your bicep against your ear and trying to create the biggest arc you can behind your back. Step 3 Circle the dowel around the full circle and rub your opposite bicep against your ear. Keep your arms straight the entire time.