Enduruc 1.2 - Heart Rate Zone Training

by Josh Kuehn

Enduruc 1.2 is our most exciting release yet. The Enduruc Apple Watch app now features personalized heart rate zones. This new workout view gives you instant insight into your current effort level, allowing you to adjust in real time based on your fitness and rucking goals.

New in Enduruc 1.2

You’ll now see live heart rate zone metrics during your workouts and a detailed breakdown after you finish—all right on your Apple Watch. We’ve also included quality-of-life improvements and bug fixes to make your experience even smoother.

Heart Rate Zone Training

Training just got smarter. Enduruc now uses your age and resting heart rate to create personalized heart rate zones tailored to your fitness level. No guesswork—just personalized, data-backed effort.

During workouts, you can swipe or use the digital crown to scroll down and view the new heart rate zone metrics. After ending a workout, the summary view will show a breakdown of how much time you spent in each zone.

What Are Heart Rate Zones?

Heart rate zones are personalized ranges that indicate how hard your heart is working during exercise. They help guide your training so you’re working at the right intensity for your goals—whether that’s improving endurance, burning fat, or increasing speed. For a deeper dive, check out this Cleveland Clinic overview of heart rate zones.

To calculate your zones accurately, Enduruc uses the Karvonen method—a more precise formula than simple age-based estimates—because it also considers your resting heart rate, a strong indicator of current fitness.

Here’s how it works:

  • Heart Rate Reserve (HRR) = Max HR − Resting HR
  • Target Heart Rate = (HRR × %Intensity) + Resting HR

Using these calculations, the app creates five training zones:

  • Zone 1 (50–60%) – Very light effort, ideal for warm-ups and recovery
  • Zone 2 (60–70%) – Light aerobic effort, great for building endurance and burning fat
  • Zone 3 (70–80%) – Moderate effort, improves aerobic capacity and general fitness
  • Zone 4 (80–90%) – Hard effort, builds speed and boosts performance
  • Zone 5 (90–100%) – Maximum effort, used for short bursts of power and intensity

Enhancements & Bug Fixes

  • New “What’s New” screen highlights recent updates
  • App now opens in month view by default
  • Improved Health and Location permissions flow on watchOS
  • Fixed: Incorrect week selection when switching from month to week view — makes it easier to stay on track

If you’re enjoying Enduruc, love the update? Leave a quick review—it’s the easiest way to support Enduruc and help others find it.