Tech halts injury: ergo expert creates tools to lessen computer user ailments.

A chair that undulates, a mouse that vibrates, a monitor suspended over a desk on a movable arm ... These are some of the newfangled ergonomic products that Cornell University ergonomist Alan Hedge studies to see if they can prevent repetitive motion injuries among the estimated 100 million people who now use computers in the United States.

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"One-third to one-half of all compensatory injuries are repetitive-motion injuries associated with office-type work," Hedge, a professor of design and environmental analysis in Cornell's College of Human Ecology, told the Cornell Chronicle Online.

Back injuries also account for one-third of all workplace injuries. A decade ago most of these were associated with heavy lifting. Today they are mostly caused by people sitting for longer periods of time--often in front of a computer.

"Now kids are using computers at age 2, so by the time they enter the work force they'll already be primed for injuries," Hedge said. "This is very serious because an injury can become life-changing; carpal tunnel, for example, is not curable. They'll have to manage this chronic condition for the rest of their lives."

In the early 1990s, Hedge reported that the average age of workers reporting carpal tunnel syndrome was late 30s to early 40s; last year, he found the average age of onset had dropped to the mid-20s and even younger for some people.

Among his recent projects:

Vibrating mouse: To see if a vibrating mouse could prevent upper extremity musculoskeletal disorders in computer users by signaling people to take their hand off the mouse to avoid overuse, Hedge and graduate student Chris Moe reported at the Human Factors and Ergonomics Society Annual Meeting in October that although subjects do remove their hands more often with a vibrating mouse than with a conventional mouse, they tended to hold their hand just above the mouse.

Undulating chairs: Another study examined whether a seat that made a continuous massaging, wavelike movement at an adjustable rate would alleviate back pain in people whose pain increases when they are seated. Although his findings were mixed, Hedge and graduate student Erin Lawler concluded that the movable seat was a promising concept, particularly for individuals with back problems.

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Movable arms for monitors: A third study looked at how suspending a flat panel computer monitor on a movable arm affects people's comfort, posture and preference. Hedge and graduate student Kathryn Boothroyd found that people unanimously liked the monitor arm because they could adjust their LCD screens, and it gave them more room on their desktops for documents.

"We saw fewer complaints about neck problems and about the workstation because people had more space," said Hedge. He was surprised, however, that users liked the versatility of the movable arm to show others what was on their screen.

"Everything we do can be summed up in the phrase, 'Good ergonomics is great economics,'" Hedge said. "More than 90 percent of a company's costs are people costs, so making small investments in improving the workplace by using good ergonomic products pays huge dividends."