For the purposes of Athlete Mode for the Renpho Bluetooth Smart Scales, an athlete is defined as someone who consistently works out for approximately 3 times a week for 2 hours. This may also apply to people, who previously worked out frequently for a long period of time but less now. This mode is also suitable for people involved in endurance sports, such as running and cycling.
If you are still wondering whether or not you should use Athlete Mode, don't worry too much about it. There is not an exact moment where you are - or are not - an athlete. Some people will get a slight underestimation on athlete mode and a slight overestimation on standard adult mode, falling into a gray area. In which case, the most important factor to look for in the Renpho Bluetooth Smart Scales is when you are given consistent readings over a period of time. Sticking with the same assessment system will likely yield a better overall picture of a person's health status. Relative changes in value are more meaningful than the absolute value of a single measurement.