The human body is a complex structure that relies on the musculoskeletal system to provide support and to assist in movement. The musculoskeletal system is an integrated system consisting of bones, muscles and joints.

While bones provide the structural framework for protecting vital organs and enabling stability, skeletal muscles maintain body alignment and create movement (Tortora and Derrickson [122]). In order for the skeletal muscles to provide these functions, they often cross at one or more joints and attach to the articulating bones that form the joint so that when a muscle contracts, movement of a joint can occur in one direction. Muscles tend to work in synergy with each other (rather than in isolation) not just to create but also to control the movement. However, muscles will waste if not used and can also become shortened if not stretched regularly.

Joints are supported not just by the muscles but also by ligaments, which are strong connective tissue structures attached to either side of the joint. Ligaments can also become shortened if they are left in one position repeatedly or over a long period of time, which can then lead to problems maintaining full joint movement.