3.2. Technical Issues with Wearable Devices and Training Monitoring
During the study, some main technical issues occurred with the use of the actigraphy devices, the smartphone app, and the PASS system.Initially, we were able to start the program with only subjects who used smartphones with the iOS system (Once the app was downloaded, however, technical problems occurred for most EG participants with the download of the training data from the health band to the app. Therefore, the EG participants trained without the desired data feedback for most of the study period.Another relevant issue was related to data synchronization from the app to the PASS (error message: “Synchronization with server failed”), which occurred with both iOS and Android systems. Consequently, coaches could not always receive the data reports and properly monitor physical activity. In several cases, the PASS reports were empty and/or contained only partial information, i.e., only data for HR or daily steps. Because participants from the EG group were not able to train with the constant support of the data feedback due to the pitfalls of the digital instruments, there was in fact no EG group. Therefore, the findings at baseline and W18 and their changes over time could not be compared between the two groups and were evaluated altogether for both groups’ participants. In addition, adherence to the AP program could not be assessed due to a lack of complete training data transfer to the server.