Usability study of wearable inertial sensors for exergames (WISE) for movement assessment and exercise

Background: Accurate assessment of movement limitations and compliance monitoring of exercises to restore movement are necessary to tailor treatments for individuals with motor deficits. Although several commercial-grade technologies are available to clinicians for evaluating movement limitations, they require one-on-one time-consuming assessments with limited reproducibility across care settings. To address these limitations, a wearable inertial sensors for exergames (WISE) system has been designed with: (I) an animated virtual coach to deliver instruction and (II) a subject-model whose movements are animated by real-time sensor measurements from the WISE system worn by a subject. This paper examines the WISE system's accuracy and usability for the assessment of upper limb range of motion (ROM). Methods: Seventeen neurologically intact subjects were recruited to participate in a usability study of the WISE system. The subjects performed five shoulder and elbow exercises for each arm instructed by the animated virtual coach. The accuracy of ROM measurements obtained with the WISE system versus those obtained with the KinectT were compared using the root mean square error (RMSE) of the computed joint angles. The subjects additionally completed a system usability scale (SUS) to evaluate the usability of the virtual coach for tutoring ROM exercises. Results: The absolute agreement between the WISE and Kinect devices was moderate to very good and it was limited because the Kinect sensor suffers from occlusion. The Bland-Altman limits of agreement for the exercises in the coronal and transverse planes were within the acceptable limits of +/- 10 degrees. The SUS response data produced relatively high third and first quartile scores of 97.5 and 82.5, respectively, with the interquartile range of 15 and the minimum score of 65, suggesting that the subjects were interested in using the animated virtual coach for tutoring ROM exercises. Conclusions: An animated virtual coach-based WISE system for mHealth is presented, tested, and validated for guided upper limb ROM exercises. Future studies with patient populations will facilitate the use of these devices in clinical and telerehabilitation settings.