A computerized biomechanical model-development of and use in studying gross body actions.

Gross body actions involved in heavy industry. e.g. lifting and carrying materials. are often the cause of injury to the musculoskeletal system. A computer model is developed which treats the human body as a series of seven links from which reactive forces and torques are computed at each articulation during various simulated materials handling tasks. In addition, an analysis of shearing and compressing forces at the lower lumbar spine is included. The assumptions of the present model are presented, along with a discussion of future models. IT HAS been reported by Troup (1965) that a relatively large portion of industrial injuries (as great as 12 per cent) are back disorders resulting from a lifting task. It is also evident from papers by Tichauer (1965), Raof et al. (1960) and Davis et al. (1965) that the estimation of stresses on various parts of the musculoskeletal system during lifting activities will require a complex methodology which takes account of such factors as (1) instan- taneous positions of the extremities and trunk, (2) curvature changes in the spine, (3) strength variations within different muscle groups and people, and (4) abdominal pressure effects.