THE SHORT ANSWER
Seiler's whole point about threshold is that the middle is seductive and expensive. Sustained moderate-hard work — the grey zone — feels productive because it hurts, but in trained riders it piles up fatigue faster than it drives adaptation. His model isn't anti-intensity; it's about making the hard work genuinely hard and rare enough that you can recover from it. Do your 20% with real intent, keep the 80% honestly easy, and the threshold sessions land. Try to live at threshold and you get the worst of both worlds: too hard to recover from, not hard enough to force the top-end adaptation.
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.
SEILER ON THRESHOLD TRAINING
Seiler’s key positions on threshold training.
- Polarised training: ~80% of sessions at low intensity, ~20% at high intensity, very little time in the threshold/tempo grey zone.
- 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.
IN SEILER’S OWN WORDS
Verbatim from Stephen Seiler’s appearances on the podcast.
“What I saw is that athlete populations from diverse sports that really weren't talking to each other or independent of each other finding the same solution to a problem to a biological challenge.”
“The key feature of polarized training is about 80% of the training is in that proverbial green zone you know the athletes are talking to each other they're doing the work and maybe they'll have a coffee in the middle of a six-hour ride but then some of the days are really tough you know and so they're doing both but they're balancing it in a way that is sustainable.”
“Those two guys said look we don't use any of these recovery modalities the only one we use is sleep and they said that we found out that if we avoid if we don't do the massage and if we don't do the whatever the cold plunge and that we have more time to sleep and sleep is our weapon you know our recovery weapon.”
HEAR IT ON THE PODCAST
Episodes where Stephen Seiler covers threshold training and related ground.
FREQUENTLY ASKED
What does Stephen Seiler say about threshold training?
Seiler's whole point about threshold is that the middle is seductive and expensive. Sustained moderate-hard work — the grey zone — feels productive because it hurts, but in trained riders it piles up fatigue faster than it drives adaptation. His model isn't anti-intensity; it's about making the hard work genuinely hard and rare enough that you can recover from it. Do your 20% with real intent, keep the 80% honestly easy, and the threshold sessions land. Try to live at threshold and you get the worst of both worlds: too hard to recover from, not hard enough to force the top-end adaptation.
What is Seiler's main point on threshold training?
Polarised training: ~80% of sessions at low intensity, ~20% at high intensity, very little time in the threshold/tempo grey zone.
Which Roadman Cycling Podcast episodes cover Stephen Seiler on threshold training?
Seiler discusses threshold training in this episode: "80/20 Training to Ride Faster | Dr Stephen Seiler".
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