A study has suggested typing on a touch-screen for lengthy periods of time could be more likely to cause muscle problems in the upper body than a conventional keyboard.
The study, commissioned by researchers at Northern Illinois University, analysed experienced touch typists of mixed sex with no history of musculoskeletal disorders in the upper body.
Touch-screen devices, unlike traditional keys on desktop PCs and notebooks, are only activated by physical contact with the skin and as such, users cannot rest their fingers on the keyboard. Instead, they must keep their wrists and fingers hovering over the screen so that they don’t accidently hit the keys, meaning muscles are left tense and motionless. The researchers believe that could lead to ‘prolonged static muscle loading’ in the shoulders.
Jeong Ho Kim, lead author of the study said: “The prolonged static muscle loading is a risk factor for musculoskeletal disorders, thus using a virtual keyboard for long periods of time may increase the risk for musculoskeletal discomfort and disorders in the shoulder.”
Participants in the study, who had been computer users for an average of 14 years and current touch-screen users with either tablets or smartphones, were asked to twice type excerpts from Grimm’s Fairy Tales on touch-screen, desktop and notebook keyboards. Electrodes recorded the level of muscle activity in their forearms and shoulders.
They discovered that, whilst muscle activity in the forearms was lowest when participants typed on a virtual keyboard, the trapezius muscles saw a higher level of activity between the neck and shoulders.
“Because a function of the trapezius muscle is to support the arms, floating the hands and forearms while typing on the virtual keyboard may have increased the static loading in the trapezius muscle and consequently resulted in higher muscle activity,” Professor Kim said.
“Although the differences were relatively small, these small exposure differences could be important when they accumulate over time.”
The discomfort with touch-screen keyboards was higher, participants said, while typing speeds and accuracy were reduced by 60% and 11%, respectively.
Use of touch-screens is becoming increasingly popular in the UK with many people now required to use a tablet at work. Physchologists recommend minimising use where possible, but if this avoidable advise users to the plug the tablet into a conventional keyboard, to limit muscle pain.