 What is 80-20 running? Popularized by Steven Sealer and Matt Fitzgerald, it's a philosophy which does away with tempo-based running. So you break down your week and you do 80% of your weekly runs at a very slow pace. That's heart rate zones one or two. And then for 20% of your running, you need to do hard sessions. Sessions where your heart rate gets into zone four or zone five. The idea being that slow running is more efficient at building stamina and endurance for long distance running and for speed. But remembering that we do need to do those fast hard sessions to build our VO2 Max. The more miles we do in a week, the faster we'll become. Running 80% of your runs really slowly means you're less tired, which means you can get out of bed the next morning and do another run. 80-20 requires you to be disciplined and controlled. It's too easy to run your easy runs hard and it's too easy to neglect the VO2 Max efforts. And that's it for today's video. Thank you for watching and I'll see you in the next one. Bye.