Elements of Ergonomics Programs A Primer Based on Workplace Evaluations of Musculoskeletal Disorders

In response to a union request, NIOSH conducted a study to evaluate whether cashiers in a major supermarket chain were developing upper extremity musculoskeletal disorders because of their jobs. The evaluation had two major components.

• The first component compared the rate of upper extremity musculoskeletal disorders in the cashiers with the rate in other supermarket workers. For this purpose, physical exams were given to both groups of workers, including range of motion, limb bending, and stretching tests. The workers rated the pain experienced for the maneuvers. Positive responses on these tests for a particular part of the body, together with questionnaire data indicating recurring or prolonged discomfort in the same area (which began after starting work at the supermarket) were defined as a WMSD. To ensure objectivity, these determinations were made by a physician who had no prior knowledge of either the existing disease state or the job titles of the workers.

• The second component consisted of direct observation and a videotape analysis of the cashier's job, measuring the number of items processed, the number of scans, and the number of keyboard entries required of the cashier. These data were used to gauge task repetitiveness, posture factors, the force required, and efficiency of movement for different checkout counter designs.

The study results indicated that the cashiers had a higher rate of upper extremity disorders than other supermarket workers for all parts of the upper body and that those cashiers with longer employment or who spent more hours per week in checkout tasks showed more evidence of such problems. Further analyses in this study sought to isolate certain checkout counter design features, tasks, and work practices as possible stress factors in light of the pattern of musculoskeletal problems noted [HETA 88–344–2092].