Range-of-motion (ROM) testing of the shoulder is part of the physical assessment to identify specific pain generators and detect muscle imbalances and other biomechanical factors that contribute to the condition. The objective of this study was to study the kinematics and muscle contribution during abduction using inertial-sensors and surface electromyography in people who perform office work and use computers. The kinematic and muscle activity during shoulder abduction movement were recorded using the FREELAB system (BTS Bioengineering, Milan, Italy). Most participants reported pain in the right shoulder (92.8%), mainly in the area of the trapezius-descendant (85.7%). The Intraclass-Correlation-Coefficient (ICC) demonstrated good-reliability. Mean-angular-velocity on both going and returning phases was higher on the painful-shoulder side (p < 0.025). The muscle with the highest contribution percentage was the middle-deltoid, followed by the long-head-biceps and the trapezius-descendant. The infraspinatus contribution of the non-painful shoulder was higher than that of the painful shoulder, and the long-head-biceps contribution of the painful shoulder was higher than that of the pain-free shoulder (p < 0.05). The long-head-biceps resisted the superior migration of the humeral head in overhead movement, as compensation for less infraspinatus activity. Performing the test with assessment technology, such as an inertial sensor and electromyography, provides information that is not visible through clinical observation of shoulder abduction movement.