Want to know what your best resting heart rate was over the last month, or how you've been sleeping? Now, you may be able to just ask the Fitbit app instead of manually digging into the data yourself.

Fitbit is working with Quest Diagnostics to see whether metrics like heart rate, heart rate variability, sleep cycles, and stress can be used to detect early signs of metabolic deterioration — a ...

If you wear a fitness tracker, you've likely seen a stat labeled "HRV" pop up on your screen. But what does it mean, and does it matter? Short for heart rate variability, HRV has become a popular ...