Heart rate variability (HRV) is the variation in the time between two consecutive heartbeats over a specific period. Doctors may use HRV as an indicator for certain aspects of a person’s health, ...

It may sound dramatic, but the rate at which your heart is beating plays a key role in how long you’re likely to live. According to expert cardiologists and academic researchers, resting heart rate ...

Garmin and Whoop devices (among others) display a stress score, but the science doesn't really add up. Here's how to actually make those scores useful.

The issue: Many runners (particularly women) report that their fitness trackers tell them they’re exercising in a higher zone ...