Abstract: The apparatus of the invention monitors spinal motion to detect movements of the lower back in lifting, bending and twisting through the use of a modified "t"-shaped collimated light beam emitted from a unit worn at the base of the spinal column and detected along the column as long as the spinal motion is within prescribed limits of flexion, extension, and left and right lateral movements--and beyond which an audible signal alert is provided as a warning of unsafe spinal movement.