Future studies show that activity trackers are starting to lose a bit of their popularity. Much of this likely has to do with consumer fatigue since, after all, activity trackers have been with us since the early 2000s, roughly 20 years now. But another important reason has to do with trackers becoming somewhat obsolete when more and more smartwatches and smartphones are tracking heart rate in addition to an array of innovative activity and health profiles. Like trackers, smartphones and smartwatches can also fit conveniently in your pants pocket, and typically do not need to be charged as often as an activity tracker, especially a refurbished one.