What do cell phones, assembly lines, computers and iPads have in common? Massage therapists know the answer: repetitive stress injuries (RSIs). As the newest member of RSI-contributing technologies, attention is turning to personal computer tablets such as the iPad.

New research indicates use of such tablets contributes to RSIs, including shoulder pain that could be more problematic than that created by traditional desktop computer use.

Investigators studied 15 experienced tablet users who completed a set of simulated tasks with two media tablets, an Apple iPad2 and a Motorola Xoom.

"During the experiment, users completed simple computer tasks such as Internet browsing and reading, game playing, email reading and responding, and movie watching," noted a press release. Head-and-neck postures and gaze angle and distance were measured using an infrared three-dimensional motion-analysis system.

"For both tablets, the gaze angle changed in a similar fashion to the head flexion across all configurations, with non-perpendicular viewing angles causing increased head and neck flexion," noted the press release. "Head and neck flexion angles were greater, in general, than reported for desktop or notebook computing."

Compared to

desktop computing scenarios, the use of media tablet computers is associated with high head-and-neck flexion postures, "and there may be more of a concern for the development of neck and shoulder discomfort," said lead investigator Jack T. Dennerlein, Ph.D., of the Department of Environmental Health, Harvard School of Public Health, and Brigham and Women's Hospital.

Only when the tablets were used in the table-movie configuration, where the devices were set at their steepest case angle setting and at the greatest horizontal and vertical position, did posture approach neutral. This suggests that tablet users should place the tablet higher, on a table rather than a lap, to avoid low gaze angles, and use a case that provides steeper viewing angles, the press release noted. However, steeper angles may be detrimental for continuous input with the hands.

"Further studies examining the effects of tablet and configuration on arm and wrist postures are needed to clarify and complete the postural evaluation," said Dennerlein.

The research was published this week in Work: A Journal of Prevention, Assessment, and Rehabilitation.

Related articles:

• Texting Craze Creating Ongoing Pain Condition?

• Computer Injuries, Beyond the Mouse