You’re committed to becoming more active and healthy. So you join a gym, find a workout buddy, or hire a personal trainer. And like more and more of us, you might also buy a fitness tracker—a wearable wireless device with built-in sensors that measure your physical activity. According to a Gartner study, 68.1 million wearable fitness trackers are expected to sell in 2015, and 91.3 million in 2016.

These mostly wrist-worn devices can tell you far more about your physical activity than the humble pedometer ever could. Current trackers—both dedicated devices and smartwatches with sensors—can measure your heart rate, distance traveled, speed, altitude, calories consumed, and even your sleep patterns the night before. As they evolve, and new kinds of sensors are built in, they can do what some targeted, wearable medical devices (such as blood glucose meters andcardiac monitors) can already do: Things like checking your breathing rate, stress level, and different types of brain activity.

Source: qz.com