What Fitness Tracker Data Is Actually Useful for Your Doctor?
Photo: Jacob Lund (Shutterstock) Whether a smartwatch or a ring, many of us now wear fitness trackers, which means we have collected a lot of data on how much we…
What Your ‘Heart Rate Variability’ Says About Your Health
Photo: BallBall14 (Shutterstock) One feature a number of fitness trackers offer is a metric called “heart rate variability,” or HRV, which is the interval of time between each heartbeat. But…