How the Spren HRV Baseline Works

At the beginning of your journey with Spren, the app is establishing your baseline. 

It will give you an estimate after 4 days - after understanding your average HRV values and how much they fluctuate. The app will continue to build your baseline for about 2 weeks - during this time, the Readiness Score may not match how you are feeling as the app is getting to know your normal HRV range and fluctuations. 

After this, the app compares each Morning Readiness reading to the established baseline to determine how far out of balance you are as compared to your individual patterns.

Ideally, you’ll form your baseline during a “normal stress” week. Exercise, work, etc. is fine during your baseline, but you don’t want to establish it during an abnormally stressful or high-volume training week or if you are sick if possible. 

The good thing is, that the baseline constantly adjusts and updates itself over time, so as your health or fitness levels change, it will learn what your new baseline patterns are. This happens on a rolling 10-day basis.