In Spain, Guerri et al. (2009) developed a mobile application for low back disorders. It could assess a patient’s muscular condition in any environment in a comfortable way. This application was based on a wireless bio-monitor and a PDA or a mobile phone. The application was evaluated in a preliminary usability, reliability, feasibility and communication performance study. The result showed that the system was easy to use, and the users were satisfied with the usability of the app in terms of both functionality and interactivity. One of the conclusions was “The possibility of using it in a mobile phone has greatly increased its usability.” In this application, mobile phones both sent data to and received data from medical devices.