Wrist velocity is an important risk factor for work-related musculoskeletal disorders in the elbow/hand, which is also difficult to assess by observation or self-reports. This study aimed to evaluate a new convenient and low-cost inertial measurement unit (IMU)-based method using gyroscope signals against an electrogoniometer for measuring wrist flexion velocity. Twelve participants performed standard wrist movements and simulated work tasks while equipped with both systems. Two computational algorithms for the IMU-based system, i.e., IMUnorm and IMUflex, were used. For wrist flexion/extension, the mean absolute errors (MAEs) of median wrist flexion velocity compared to the goniometer were <10.1 degrees/s for IMUnorm and <4.1 degrees/s for IMUflex. During wrist deviation and pronation/supination, all methods showed errors, where the IMUnorm method had the largest overestimations. For simulated work tasks, the IMUflex method had small bias and better accuracy than the IMUnorm method compared to the goniometer, with the MAEs of median wrist flexion velocity <5.8 degrees/s. The results suggest that the IMU-based method can be considered as a convenient method to assess wrist motion for occupational studies or ergonomic evaluations for the design of workstations and tools by both researchers and practitioners, and the IMUflex method is preferred. Future studies need to examine algorithms to further improve the accuracy of the IMU-based method in tasks of larger variations, as well as easy calibration procedures.

Wrist angular velocity assessment is important for assessing the risks in hand-intensive work. This study compared the measurement accuracy of an inertial measurement unit (IMU)-smartphone system, an electronic goniometer and an optical tracking system (OTS) for measuring wrist flexion velocity. Six participants performed three sets of standard hand/wrist movements and three simulated work tasks. The results showed the IMUs had adequate accuracy comparing to the OTS during standard movements of low to medium pace. The accuracy of the IMUs compared to the OTS was lower during fast pace movements and simulated work tasks. Still, the IMUs had in general small differences compared to the goniometer in flexion/extension and simulated work tasks. Therefore, the IMU system may be used by researchers and practitioners for assessing wrist flexion velocity in hand-intensive work. Future studies need to explore algorithms to improve the IMU-smartphone system and reduce errors.