2.1. Study Design
AHC, MetS
Participants were full-time professionals, managerial, or clerical workers recruited from five companies, each with more than 1000 employees located in the Tokyo metropolitan area in Japan. The original study was a randomized controlled trial (RCT) of a smartphone lifestyle intervention application. Participants eligible for the RCT were employees that had completed the annual health check-up (AHC) and had been categorized with MetS or were considered to be at risk of MetS based on their AHC results. The participants of the original RCT were recruited among 7437 eligible employees. A total of 272 participants were enrolled and randomized into 2 arms: 181 were in the intervention group and 91 were in the control group. Participants in the intervention group were asked to use a wearable device 24 h per day and a dedicated smartphone application for the entire 3 months of the study. Participants in the control group completed a questionnaire using a dedicated smartphone application. All participants received detailed information about the study both in writing and face-to-face. Information provided to study participants included, but was not limited to, ethical considerations, the purpose of the study, and the right to discontinue at any time without penalty. All participants understood that participation was entirely voluntary and provided written informed consent. The study was approved by the Ethics Committee of the School of Engineering, the University of Tokyo (approval number: KE18-44). Participants in the intervention group were gifted the wearable device as an incentive if they completed the final questionnaire at the end of the study. Participants in the control group were gifted the wearable device at the end of the study.