Abstract

The shoulder is the joint most affected by musculoskeletal disorders (MSDs), after the back, and accounts for 10% of compensated occupational injuries in Québec workers. Current knowledge does not allow the injury mechanisms to be understood, or workplace prevention recommendations to be validated for the loads to be moved, permissible heights, or prescribed postures. Currently, only the repetition factor is associated with shoulder tendinopathies. The relationship between load and posture is more complex to establish, but it is assumed that, just as with the back, excessive tissue loading is responsible for the majority of shoulder MSDs. This loading cannot be directly measured; modeling therefore remains the best means of evaluating its magnitude.

Sixteen people will participate in experiments in which their movements will be measured while they are performing predefined handling tasks. Movement of the joints and muscular forces will be estimated; the range of movement and muscle activation in the shoulder will be compared for heights and loads.

These experiments will allow the researchers to develop a biomechanical model for evaluating the level of risk of shoulder injury during task performance. Initially, they will develop a protocol and a method for estimating joint movement and muscle forces in the shoulder during complex tasks. They will then will apply this protocol to workers in different sectors and professions, which should identify the least constraining strategies for the musculoskeletal system, provide a better understanding of injury mechanisms, and finally, allow ergonomic recommendations to be issued for limiting shoulder loading.