These days, it may seem like there’s a million different data points that you’re supposed to keep track of—hello, steps, sleep, and recovery scores!—and it’s difficult to know which ones are worth ...

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 ...

Your heart beats around 100,000 times every day. Heart rate is a key marker of cardiovascular activity and an important vital sign. But your pulse is not as steady as a precision clock – nor would you ...