Most people run every session at the same medium-hard effort. Endurance athletes do the opposite: most of their training is easy, and the hard sessions are kept truly hard.
// 01Why it works
- It's how the best train. Reviews of elite endurance athletes find that roughly 80% of their training sessions are done at low intensity, with the rest hard.
- Volume without burnout. Easy sessions build your aerobic base but cost little recovery, so you can train more often and stay consistent.
- Better hard days. Fresh legs make intervals count. In one trial, 4×4-minute intervals raised VO2 max more than moderate steady training did.
The exact physiological edge of zone 2 over other easy intensities is still debated. The training pattern itself is well documented.
// 02How to do it this week
- Find the zone: you can talk in full sentences but not sing. That's about a 3–4 out of 10 effort.
- Using heart rate? Estimate max HR as 208 − 0.7 × age (the older "220 − age" formula is less accurate), then aim for about 60–70% of it. It's still only an estimate.
- Do 2–3 sessions of 30–45 minutes: brisk incline walking, easy cycling, rowing or jogging.
- Slow down when it drifts. Walk the hills if you need to.
- Keep 1–2 hard sessions, like intervals, and make everything else easy.
Common mistakes: letting easy days creep into "medium," judging progress after a week instead of a couple of months, and trusting wrist heart rate over how the effort actually feels.
Not medical advice. Talk to a doctor before changing your training if you have a health condition or are new to exercise. See the full disclaimer.
Sources
- Seiler S. Best practice for training intensity distribution in endurance athletes. Int J Sports Physiol Perform, 2010. PubMed 20861519
- Helgerud J et al. Aerobic high-intensity intervals improve VO2max more than moderate training. Med Sci Sports Exerc, 2007. PubMed 17414804
- Tanaka H et al. Age-predicted maximal heart rate revisited. J Am Coll Cardiol, 2001. PubMed 11153730