A study of forearm muscle activity and wrist kinematics in symptomatic office workers performing mouse-clicking tasks...

The present study examined various biomechanical parameters in symptomatic and asymptomatic computer users during mouse-clicking tasks with different speed and precision demands. Surface electromyography (EMG) of right wrist flexors and extensors were compared between individuals with computer-related wrist/hand symptoms (n=9) and pain-free controls (n=8). Each subject performed four mouse tasks with high and low precision, constant and fastest speed of 5 min each. Results showed that Case subjects recorded significantly lower EMG amplitudes during maximum voluntary contractions in three out of four forearm muscles (p=0.001-0.019). Normalised median amplitudes of extensor carpi radialis and flexor carpi ulnaris showed significant differences between groups in the speed conditions (p=0.01, 0.04, respectively). Case subjects reported significant discomforts in the wrist/hand region in all tasks, while recorded significantly longer response time and fewer mouse clicks compared to controls. Results suggested that forearm muscles in symptomatic individuals were inhibited in their maximal activation as well as during functional tasks, and this may imply altered motor control mechanisms in forearm muscles contributing to work-related musculoskeletal disorders.