The effects of typing speed and force on motor control in symptomatic and asymptomatic office workers

Office workers commonly suffer from Work-related Neck and Upper Limb Disorders (WRNULD) due to prolonged computer use. The speed and force performance in the keystroke actions are important elements in motor control that can be influenced by musculoskeletal symptoms. This study examined the keystroke performance of symptomatic and asymptomatic office workers when they were challenged by the demands of increased speed and force of keyboard operation. Two groups of female office workers were compared in terms of their keystroke dynamics during three typing conditions which involved normal typing speed and force ("Normal"), typing with increased speed ("Faster") and typing with increased force ("Harder"). The results showed that both the Case Group (n=21) and the Control Group (n=20) performed with similar levels of Mean Speed and Mean Peak Force in the Normal condition. The Case Group subjects reported significantly increased discomforts in the Faster and Harder conditions but not the Control Group. In the Faster condition, the Case Group showed trends for greater Speed and Force Variability. In the Harder condition, the Case Group showed more associated increase in Mean Speed while achieving a lower increase in Mean Force. These differences were even more apparent when Case Group was sub-divided into High-Low Discomfort sub-groups. The results may suggest a relationship between musculoskeletal discomforts and the speed and force control in keystroke actions. Relevance to Industry: The control of speed and force in typing are important components of occupational exposure in office workers, and they may have implications towards explaining why some workers get WRNULD and others do not. The results suggest that symptomatic individuals may respond differently when ergonomic interventions are introduced.Department of Rehabilitation Science