Most fitness trackers offer a wealth of heart-rate data. Here’s how to make sense of it. By Talya Minsberg If you wear a smartwatch or fitness tracker, you likely already have access to a steady ...

A few weeks back, we reported on a research group that figured out how to measure heartrate using perturbations in WiFi signals. [Nick Bild] was interested in this so-called “Pulse-Fi” technique, but ...