Garmin Forerunner 645

You do the running. Forerunner 245 Music does the thinking. This GPS running smartwatch evaluates performance stats such as VO2 max, aerobic and anaerobic training effects, and training status, which indicates if you’re under training or overdoing it. 

You can also track advanced running dynamics such as ground contact time balance and stride length. Store up to 500 songs right on your watch for phone-free listening, and even sync your favourite music from select streaming services.