80/20 is a way to organise training: most of your running stays easy, with a smaller share at a harder effort. I use it as a weekly check, not an exact quota. Count minutes, keep your zone method consistent, and adjust the harder work to your experience and recovery.
What does 80/20 count?
For my training log I count time in heart-rate zones. Easy means the low-intensity range in the method I am using. A distribution by session goal can give a different percentage. State which method you used before comparing two weeks.
What does the research show?
Muñoz and colleagues compared training distributions in 30 recreational runners over 10 weeks. Both groups improved their 10K performance; the main difference between groups was not statistically significant. This supports considering mostly easy training, without promising a particular improvement.
How do I use it in a real week?
Start with the amount of running you already recover from. Protect easy days around demanding sessions. If the week has gone badly, remove intensity rather than adding hard minutes to make the chart reach 20%.
What does my own month look like?
From 21.09 to 18.10.2026 I recorded 24 runs, 229 km and 81% of time easy, using a chest strap. That is one dated example. Your useful starting point is your own recent training, not my kilometres.
A worked example with 150 minutes
If your log contains 120 easy minutes and 30 minutes above the easy range, the total is 150 minutes: 120 ÷ 150 = 80% easy, 30 ÷ 150 = 20% above easy. Classify recorded minutes consistently, including warm-ups and cool-downs. This is arithmetic, not a prescription for 30 hard minutes.
What if you run three or four times a week?
One harder session out of three is not automatically 33% hard time: the sessions can have different lengths and include easy running. I would not add a fourth run or extra intensity just to reach 80/20. The study above is evidence about its participants and protocol, not a trial of every possible three-day or four-day schedule.
