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AnswersWhat is the 80/20 rule in endurance training?
The 80/20 rule is the observation that successful endurance athletes do roughly 80% of their training at low intensity and about 20% at moderate to high intensity. It comes from studies of how elite rowers, runners, skiers and cyclists actually train, most influentially Stephen Seiler's. It is a description of what works, not a law — but it is a good default for amateurs, who tend to do far too much in the middle.
How it is counted matters
Count by session and a threshold run looks like a hard day. Count by minute and it is mostly easy: a warm-up, a cool-down and recoveries around perhaps twenty minutes of real work. Race Shape counts by the interval, not the session, which is why a plan that feels like it has three hard days a week can still be close to 80/20.
| A typical threshold run | Where the minutes go |
|---|---|
| Warm-up and easy running | 21 min — easy |
| 2 × 10 min at threshold | 20 min — hard |
| Recovery jog | 2.5 min — easy |
| Cool-down | 10 min — easy |
| This session, counted by minute | about 63% easy, 37% hard |
Why amateurs drift away from it
With limited time, every session feels like it should count, so easy days get run a little hard and hard days get run a little easy. The result is a lot of moderate running that is too hard to recover from and too easy to drive improvement. Protecting the easy days is usually the single change that improves a self-coached athlete most.
Common questions
Is it 80/20 by time or by sessions?
By time is the more useful measure. By sessions, a typical week might be two or three hard days out of six.
Does it apply to beginners?
Yes, arguably more. New athletes have the most to gain from aerobic volume and the least ability to absorb a lot of intensity.
Is polarised training the same thing?
Closely related. Polarised training pushes the hard 20% towards genuinely high intensity and keeps the middle zone almost empty; 80/20 describes the split without being as strict about the middle.
Sources
- Seiler, K. S. & Kjerland, G. Ø. (2006). Quantifying training intensity distribution in elite endurance athletes: is there evidence for an "optimal" distribution? Scandinavian Journal of Medicine & Science in Sports.