Shoulder loading while performing automotive parts assembly tasks: A field study

The purpose of this study was to complete in depth task analyses for a series of automobile parts assembly jobs and quantify the range of mechanical shoulder loading sustained by the workers. Nine jobs were selected from within an automobile parts assembly plant and 26 participants (12 males, 14 females) were filmed while they performed regular assembly line duties. Workers spent the majority of their time in neutral shoulder postures, and about 1/3 of the shift in mild shoulder flexion or abduction. Cumulative shoulder flexion moments ranged from 76-160 kNm*s while cumulative shoulder abduction moments ranged from 42-119 kNm*s. Peak shoulder flexion moments ranged from 26-124 Nm and peak shoulder abduction moments ranged from 30-93 Nm. The analysis revealed a wide range of shoulder loading between jobs, and workers completing the same job. This study demonstrates the importance of measuring a variety of postural and mechanical demands for every job to adequately address all aspects of the work that might influence the development of injury. This is the first study to document entire shift cumulative shoulder moments during automotive parts assembly work. This quantitative assessment provides insight into the range of loading that workers are currently experiencing, and demonstrates the variability between workers completing the same task.