Range of motion (ROM) exercises provide a way to maintain joint flexibility. In passive ROM, someone moves the joints with no assistance from the customer. In active ROM, the customer does the exercises alone or with the devices' assisatance, such as a strap. ROM is important to prevent contractures. A contracture is a shortening of muscles, tissues, tendons, and skin at the joints, due to lack of movement and exercise. When joints continue bent over time, they can no longer be straightened.