Journal

Train smarter.

Practical articles on heart rate, recovery, sleep and training.

What is HRV and why should you care?

HRV stands for heart rate variability — the tiny difference in time between your heartbeats. And it says surprisingly much about how fit you are.

The Pro X gives a daily score from 0 to 100. But what does 67 vs 82 actually mean? And when should you really rest?

We compared 12 trackers in this price range on battery, accuracy and features. One caveat: yes, we make a tracker ourselves.