Validity and reliability of upper extremity three-dimensional kinematics during a typing task

Computer use continues to be considered a risk factor for work-related musculoskeletal disorders despite a greater awareness of the risk associated with excessive use, the implementation of safety features and the introduction of extensive interventional programs. Better understanding of risk factors in movement patterns is needed. This study identified the most suitable variable for work-related upper extremity motion analysis as being peak-to-peak range of motion. Assessment was by three-dimensional motion analysis for upper extremity ergonomics. The study was designed to validate and examine the reliability of these parameters in the setting of keyboarding. Sixty-two right-hand dominant participants (non-skilled typists) were recruited. Motion analysis was performed using the Cartesian Optoelectronic Dynamic Anthropometric CX-1 (CODA) system with markers which were attached to the right hand, elbow, wrist and fingers. Range of motion and angular velocity were recorded while the subjects repeatedly typed a predetermined sentence five times. The re-test examination was repeated after an interval of one week. The findings clearly demonstrated discriminative validity in wrist range of motion (p<.01), test-re-test, reliability (83>ICC>.70) and inter-rater reliability (95>ICC>.70) for most variables. The CODA system has considerable potential for understanding movement patterns in the upper extremities. These findings can provide the basis for future studies on the efficacy of ergonomic intervention programs.