A prospective study of computer users: II. Postural risk factors for musculoskeletal symptoms and disorders.
Marcus-M; Gerr-F; Monteilh-C; Ortiz-DJ; Gentry-E; Cohen-S; Edwards-A; Ensor-C; Kleinbaum-D
Am J Ind Med 2002 Apr; 41(4):236-249
Background: Despite widespread recommendations regarding posture during computer use, associations between specific postures and musculoskeletal health are not well characterized. Methods: Six hundred and thirty-two newly hired computer users were followed prospectively to evaluate associations between posture and neck or shoulder (N/S) and hand or arm (H/A) musculoskeletal symptoms and musculoskeletal disorders. Participants' postures were measured at entry and they reported symptoms on weekly diaries. Participants reporting symptoms were examined for specific disorders. Multivariate Cox regression models were used to estimate associations between postural variables and risk of symptoms and disorders, controlling for confounding variables. Results: Keying with an inner elbow angle > 121°, greater downward head tilt, and presence of armrests on the participants chair were associated with lower risk of N/S symptoms or N/S disorders. Keying with elbow height below the height of the "J" key and the presence of a telephone shoulder rest were associated with a greater risk of N/S symptoms or N/S disorders. Horizontal location of the "J" key > 12 cm from the edge of the desk was associated with a lower risk of H/A symptoms and H/A disorders. Use of a keyboard with the "J" key > 3.5 cm above the table surface, key activation force > 48 g, and radial wrist deviation of > 5° while using a mouse was associated with a greater risk of H/A symptoms or H/A disorders. The number of hours keying/week was associated with H/A symptoms and disorders. Conclusions: The results suggest that the risk of musculoskeletal symptoms and musculoskeletal disorders may be reduced by encouraging specific seated postures.
Musculoskeletal-system-disorders; Epidemiology; Keyboard-operators; Computer-equipment; Office-workers; Risk-factors; Job-stress; Physical-stress; Repetitive-work; Cumulative-trauma-disorders;
Author Keywords: musculoskeletal disorders; computer; video display terminal; prospective study; ergonomics; posture
Fredric Gerr MD, Department of Environmental and Occupational Health, Rollins School of Public Health, Emory University, Atlanta, Georgia
Disease and Injury: Musculoskeletal Disorders of the Upper Extremities
American Journal of Industrial Medicine
Emory University, Atlanta, Georgia