Isolated planar trunk strength and mobility measurement for the normal and impaired backs: Part I — The devices

Abstract The isolated and planar human trunk strength and mobility measurement have been somewhat elusive due to lack of appropriate devices, however much needed. Four devices (FELT-I, FELT-II, AROT and SDST) have been designed, fabricated and calibrated to measure trunk flexion, extension, lateral flexion, and axial rotation of the normal as well as the injured subjects safetly. The simulataneous measurement of the isolated planar force and motion will allow determination of the strength capability with changing posture. Such isolated values may allow a better understanding of tissue tolerance as related to specific loads among normals. It may also allow characterization of generalized problem among injured or impairment restricted to a small range. The calibration of the fabricated devices was linear within the range of the human capability. In extensive testing of 179 subjects, the devices proved to be robust and reliable. Relevance to industry This paper is relevant to industry in two ways. One, the devices reported here are new products for possible manufacturing and marketing. Second, through the use of these devices isolated strength capabilities will permit resolution of industrial tasks in their fundamental components allowing a better strength-matched job design to enhance safety. Also, functional impairment of injured workers can be determined.