Yes, you can do fitness with this watch, just like with the vivoactive 4. It offers more or less the same basic fitness and health functions, with improvements such as a more accurate heart rate sensor and more sports modes (over 30 compared to 20), but no barometric altimeter or guided exercise animations. The battery is larger (up to 11 days in watch mode compared with 7-8), and it includes heart rate measurement, swimming and skiing, which are Android/iOS compatible.