Work hardening, or strain hardening, is an increase in mechanical strength due to plastic deformation. In metallic solids, permanent change of shape is usually carried out on a microscopic scale by defects called dislocations which are created by stress and rearrange the material by moving through it. At low temperature, these defects do not anneal out of the material, but build up as the material is worked, interfering with one another's motion and thereby increasing strength and ductility is decreased by considerable amount.
A technique that assists an injured employee to gradually readjust to the physical demands of a job. The injured employee practices job-related tasks using less weight, a shorter period of time, or slower pace than is required in the actual job.