Easy endurance: why running slowly makes you run fast
Easy endurance is the comfortable pace, the one where you can speak in full sentences. It makes up 70 to 80% of a plan's volume, and it builds the base that quality sessions rely on. Here is how your AI coach frames it, and how heart rate tells you when you are running too fast.
Last updated: October 27, 2026
What easy endurance builds
At low intensity the body develops its capillary network, mitochondrial density and the ability to use fat as fuel. These are the adaptations that let you hold a marathon, and that make quality sessions more productive.
It sits between 60 and 70% of VMA, or 65 to 75% of maximum heart rate. With a VMA of 15 km/h, that is a pace of 5:45 to 6:40 per kilometre: much slower than most runners think.
Why you should watch heart rate too
Easy pace varies with heat, terrain, fatigue and sleep; heart rate says what the body is actually doing. The easy runs of Running Workout plans reach your watch with a pace target, in percent of your MAS: keep an eye on heart rate and slow down if it goes above 75% of your max HR. Prefer a heart-rate target? Ask your assistant for an easy run targeted by heart rate, and it sends it to your watch.
If your max HR is not known, the coach estimates it from your Garmin activities, tells you, and proposes to confirm it. It never invents it.
The most common mistake
Running easy runs too fast. The grey zone, between 75 and 85% of max HR, tires without building endurance and without stimulating threshold. It is mistake number one for runners who plateau despite high volume.
- 60 to 70% of VMA, 65 to 75% of max HR.
- Speaking in full sentences must stay possible.
- 70 to 80% of weekly volume.
The coach's weekly review spots easy runs done above target in Garmin activities and points them out. Slow down is the most frequent advice it gives, and the most effective.
Frequently asked questions
Do I really have to run that slowly?
Yes. Progress comes from the contrast between easy and hard sessions. An easy run at 80% of max HR is neither.
How do I know I am in easy endurance?
You can speak in full sentences, and your heart rate stays under 75% of your maximum. The watch shows it live, and alerts you outside the range when the workout carries a heart-rate target.
Should a beginner walk?
Often, yes: if running slowly pushes HR above 75%, alternating walking and running keeps intensity in the right place. The restart plan builds it in.
Let your assistant write your sessions
Running Workout connects Claude, ChatGPT or Gemini to your Garmin account through the official API. Nothing to install, and no Garmin password to hand over.
See the connection guide