Biomechanical model for optimal postures in manual lifting tasks

A mathematically simple but revealing biomechanical model was employed to investigate and clarify the role of various biomechanical factors such as magnitude of load, individual anthropometric characteristics, shape, size and location of loads, etc., involved in the load lifting process. From the model, the concept of determining optimal lifting postures based on minimizing the reaction force at the L4/L5 joint subject to all other muscle/joint complexes not being overstressed is developed. Various moment-load relationships for the various joints are computed along with moment-moment relationships between various joints which were shown to well match experimental results. The model was able to propose many interesting and practical suggestions in the area of manual material handling tasks, especially the lifting aspect.