The leading metrics among U.S. wearable users are fitness-related, according to a recent survey by eMarketer. When asked what health/fitness metrics do U.S. wearable users track with their devices, 59 percent count on these devices to tally their daily steps, and 42 percent use the tech to track workouts. According to the survey, 32 percent track calories with their devices and 17 percent track stress levels. Meanwhile, just 8 percent monitor chronic health conditions with smartwatches, fitness trackers, and the like.