Cybersecurity researchers at the University of Toronto examined eight popular wrist-worn trackers. They tested how they communicate with mobile apps and even upload and store a user's workout information on manufacturers' computer servers. The researchers conclude that several models expose users to potential internet snoops and hackers even when devices aren't being used for exercise and mobile apps are turned off. Each of the devices uses Bluetooth technology that emits a signal and a unique ID that can be detected even when the tracker is not paired with a mobile phone. This "can leave their wearers exposed to long -term...