Back-end for an Android Application

Develop a mobile application / mobile-friendly website that provides information on how much a person should train in the future based on their historical training load data. The application will have the following features: 1. Set up a basic profile 2. Record their training sessions 3. Display useful stats of each training session (particularly if data is from fitness devices) 4. Show what a user’s future training load range should be within 5. Evaluate a proposed target and track progression 6. Communicate with a network of friends  User interface must be: - Simple and easy to use - Any manual entry requirements to be as “automatic” as possible - Consider a start/stop function to automatically calculate duration. On “stop” it should ask “how hard was this session?”. Linking to GPS metrics in the phone is recommended too - Have an engaging/attractive user interface with appropriate graphics - Designed for the purpose of being used by the general population, regardless of age or fitness level - Have reminders to the individual of their daily training load prescription, with some suggested exercises - Provide instant feedback to the user in terms of recommended future training loads  Data storage/analytics requirements: - Store data of all users in a central database - Ability to conduct aggregate analysis such as average weekly training load of all users aged [x], etc - Ability to store identifiable or unidentifiable data - Data exportable in wide or long format as a .csv file for analysis