Abstract: A device for preventing or relieving pain in the lower back of a human subject includes a body-engaging element configured for engaging a region of the subject's body inferior to the lumbar vertebrae while the subject lies in a supine position. A drive mechanism is configured to move the body-engaging element through a repetitive cyclic motion which includes an operative motion along a first path including a primarily vertical lifting motion followed by a primarily horizontal tensioning motion, and a return motion along a second path, the second path lying generally below the first path. The body-engaging element preferably includes at least one surface configured for engaging a rear surface of both of the subject's legs from the knees downwards.