JMIR Publications

ABSTRACT

Background:

Device-based measurements of physical behavior, using the current methods, place a large burden on participants. The MOTUS system could reduce this burden by removing the necessity for in-person meetings, replacing diaries written on paper with digital diaries, and increasing the automation of feedback generation.

Objective:

To describe the development of the MOTUS system and evaluate the potential of MOTUS to reduce participant burden in a two-phase usability evaluation.

Methods:

MOTUS was developed around 1) a thigh-worn accelerometer with Bluetooth data transfer, 2) a smartphone app containing an attachment guide, a digital diary, and facilitating automated data transfer, 3) a cloud infrastructure for data storage, 4) an analysis software to generate feedback for participants, and 5) a web-based app for administrators. We recruited 19 adults (mean age [SD, range] 45 [11, 27-63] years, 11 female) to assist in the two-phase evaluation of MOTUS. In phase one, seven participants evaluated the usability of mockups for a smartphone app. Participants interacted with the app while thinking aloud and any issues raised were classified as critical, serious, or minor, by observers. This information was used to create an improved and functional smartphone app for evaluation in phase two. In phase two, 12 participants completed a 7-day free-living measurement with MOTUS. On day 1, participants attempted 20 system-related tasks under observation, including; registration on the study webpage, reading the information letter, downloading and navigating the smartphone app, attaching an accelerometer on the thigh, and completing a diary entry for both work and sleep hours. The success of task completion and any issues encountered were noted by the observer. On completion of the 7-day measurement, participants provided a rating from 0 to 100 on the System Usability Scale and participated in a semi-structured interview aimed at understanding their experience in more detail.

Results:

Task completion rate was 100% for 13/20 tasks, >80% for 4/20 tasks, and <50% for 3/20 tasks. The average rating of system usability was 86 on a 0-100 scale. Thematic analysis indicated that participants perceived the system as easy to use, easy to remember, and subjectively pleasing overall. Participants with shift work reported difficulty with the entry of sleep hours, and 66% of the participants experienced slow data transfer between the app and the cloud infrastructure. Finally, a few participants desired a greater degree of detail in the generated feedback.

Conclusions:

Our two-phase usability evaluation indicated that MOTUS can reduce the burden of device-based measurements on participants. Issues around the system’s slow data transfer, participants with atypical work shifts, and the degree of automation and detail of generated feedback, should be addressed in future iterations of the MOTUS system.