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Cornell ergonomist offers web guidelines on how children can avoid injury while at their computers

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sitting at a computer
sitting at a computer
Photograph (from a research videotape) on the left shows the incorrect posture of a tall eighth grader for sitting at a computer with both elbows and knees at angles less than 90 degrees. Photo on the buttom shows correct posture.

American children typically spend between one and three hours a day at a computer, putting them at high risk for wrist, neck and back problems, says a Cornell University ergonomist.

The problem is their sitting position. The rule of thumb is that knees and elbows should be placed at an angle of 90 degrees or greater, says Alan Hedge, professor of design and environmental analysis at Cornell and director of Cornell's Human Factors and Ergonomics Laboratory, speaking at the National Ergonomics Conference in Anaheim, Calif., in December. To help schools and parents provide safer workstations, Hedge is offering guidelines on the World Wide Web. The site, at, provides articles on "Workstation Ergonomics Guidelines for Computer Use by Children," "Ergonomics and Children: How to Prevent Injury in the Classroom" and "Ergonomic Guidelines for Arranging a Computer Workstation -- 10 Tips for Users."

Hedge, who has co-authored several research papers on how computer use by schoolchildren puts them at high risk for injuries, now offers ways to combat these injuries. Among his recommendations: Students should have good back support, place their feet on the floor or on a footrest, and the angles of their elbows and knees should be no tighter than 90 degrees. Perhaps most important is wrist angle: wrists should be in a flat, neutral position while typing.

"This is best achieved by using a keyboard on a lowered, negatively sloped keyboard tray. In schools, computer stations should be adjustable," Hedge says. "Our studies indicate that without any instruction, middle-school students, for example, reduce their risk for musculoskeletal problems when they work at an adjustable, ergonomically designed workstation."

In his presentation at the conference, Hedge pointed out that:

  • 95 percent of schools now have computers for student use;
  • There are 4.4 million computers in American schools, with an average student-to-computer ratio of 10-to-1;
  • 63 percent of 9- to 17- year-olds prefer web surfing to watching TV;
  • Internet savvy students get more A's than other students but do worse in spelling, punctuation and grammar;
  • At present rates, today's children will spend more than two years during their lifetimes on e-mail and more than 23 years on the Internet.

Hedge will be presenting a paper on children's ergonomics with his colleague, Associate Professor Lorraine Maxwell, and graduate student Marisol Marrero at the 24th Triennial Congress of the International Ergonomics Association, to be held in conjunction with the 44th annual meeting of the Human Factors and Ergonomics Society, July 30 to Aug. 4 in San Diego.