Equally important is the remodelling of soft tissue structures, muscles and ligaments, in order to maintain the corrected posture. These are important questions to the chiropractor interested in spinal correction and they can only be answered through an understanding of rheology. To put it simply, rheology looks at why various materials react differently when loads are placed upon them. All materials possess these four properties in some proportion, however, to explain each property we will discuss each in its ideal form. The symbol for elasticity is shown as a zig-zag line which represents a perfect spring.
Plasticity is represented by a block resting on a base with friction between the two surfaces.
The viscous element is idealized as a dashpot, or a vein immersed in a viscous fluid. In a perfect elastic element, deformation is immediate and proportional when a force is applied. The elastic deformation of a rubber band is easily visible to the unaided eye whereas the elastic deformation of a steel beam would require delicate instruments to measure. Plasticity is best explained by picturing a heavy box on a flat surface. However, once friction is overcome deformation is constant and proportional.