STEPHEN SEILER

WHO IS STEPHEN SEILER?

Stephen Seiler is the exercise physiologist who, more than any other researcher, defined how modern endurance athletes structure their training. Working from his lab at the University of Agder, he documented that elite athletes across cycling, rowing, cross-country skiing and running converge on the same intensity distribution — roughly 80% easy, 20% hard, with very little time in the middle. That observation is now known as polarised training and the 80/20 rule, and it is the framework Roadman builds every training conversation on.

KEY IDEAS

The major positions Seiler is known for in cycling and endurance sport.

• →Polarised training: ~80% of sessions at low intensity, ~20% at high intensity, very little time in the threshold/tempo grey zone.
• →Elite endurance athletes across disciplines converge on the same intensity distribution — it is not a coaching opinion but a measured pattern.
• →The biggest single mistake amateurs make is riding their easy days too hard, which compromises the quality of their hard days.
• →Long, slow distance is the irreplaceable foundation — high-intensity work without an aerobic base produces short-lived gains.
• →Heart rate, RPE, and lactate at sub-2 mmol/L are all reliable markers for genuine Zone 2 — power alone misses the day-to-day variation.