80/20 training

80/20, or polarized training, means doing about 80 % of your running easy and 20 % hard. It is how most endurance athletes train.

• Easy means conversational: you can speak in full sentences, roughly below 75 to 80 % of your maximum heart rate.
• The hard 20 % is intervals, tempo or hills: 1 to 3 quality sessions a week, no more.
• The trap is the middle: running every run « moderately hard » leaves you too tired for real quality and too fast to build endurance.
• Count it in time, not in sessions: with 4 hours of running a week, about 50 minutes are hard.

Slowing down your easy runs is often the quickest way to get faster.