Tag: strain

All the articles with the tag "strain".

Zenith 101 Fitness

Heart Rate Zones: How Zenith Calculates Yours and How to Use Them

Zenith uses six heart rate zones built on your personal heart rate reserve. Here's how they're calculated, what each zone does, and how to use them to hit your strain target.


Zenith 101 Fitness

How Zenith Measures Strain

Strain is the single number that tells you how hard your day was. Here's how Zenith calculates it from your heart rate, your lifting, and everything in between.