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Adjustable keyboard and mouse trays lower posture risks for middle schoolers working at computers, Cornell study finds

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Middle school students put themselves at risk for musculoskeletal problems when they work at a computer keyboard on a desktop instead of from an adjustable computer tray, according to a new Cornell University study.

"At traditional desktop workstations, these middle school students definitely sat in at-risk positions for potential musculoskeletal problems when using computers," says Kathryn Laeser, who conducted the study for her Cornell Master's thesis last year. "They reduced their risk, however, when they worked at an adjustable, ergonomically designed workstation."

Without any instruction, students consistently assumed better posture at the adjustable workstation and maintained that posture throughout keyboarding and mousing tasks, she says. The upper arm, in particular, was taken out of high-risk positions at the adjustable workstation.

However, although the improvements were statistically significant for the forearm, neck, wrist and trunk, they were only modest and did not fall into low-risk ranges, says Laeser, now a facilities planning consultant in San Francisco.

In the study, published in the winter issue of the Journal of Research on Computing in Education (Vol. 31, No. 2, pp. 173-188), 58 students in grades six and eight first used a keyboard and monitor on a desktop. Then they used a preset tiltdown keyboard system, consisting of a negative slope tiltdown keyboard tray and a mousing surface positioned closer to the student's body. The students' posture was assessed at both types of workstation arrangements using a standard observational measurement tool.

The study was under the supervision of co-authors and professors Lorraine Maxwell and ergonomist Alan Hedge, both in the design and environmental analysis department at Cornell. Hedge had reported in 1995 that the lowered keyboard tray on a gentle, negative tilt away from the user puts 60 percent more typing movements within a low-risk zone for carpal tunnel syndrome.

In the latest study, Laeser also found that more students preferred working at the adjustable workstation.

Laeser's findings were similar to another recent Cornell study of elementary schoolchildren working at computers, published in Computers in Schools (1998, vol. 14, issues 3/4, pages 55-63). The researchers found that almost 40 percent of third to fifth graders studied used computer workstations that put them at risk for developing musculoskeletal problems. None of the 95 students studied scored within acceptable posture ranges.

Laeser's study was supported by the College of Human Ecology at Cornell.

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For a slide show summarizing the study, see

For information on the Department of Design and Environmental Analysis, see