Using touch-screen keyboards on tablet computers for long periods of time could lead to strain in the shoulders, suggests a study in the November issue of Applied Ergonomics that compared the musculoskeletal impact of three types of keyboards.

The small study found touch screen, or virtual, keyboards, which lack a feedback mechanism indicating a key has been pressed, require less typing force and finger-muscle activity than conventional keyboards. But tablet users must keep their fingers hovering above the keyboard to avoid...