The Physiology of Endurance Running Podcast Your guide to Zone 2!
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Jan 14, 2026 A deep dive into the controversy around Zone 2 training and why the term can be misleading. They unpack physiological definitions like LT1 and the problems with precise boundaries. Practical ways to estimate the zone in the field are shared, plus discussion of how easy volume builds mitochondrial and musculoskeletal resilience. They finish with programming tips and cautions about personalization.
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Zone 2 Is Overused Label For Easy Running
- 'Zone 2' is often just easy running rebranded and used imprecisely by the public.
- Sports science defines it more precisely around physiological thresholds, especially LT1.
Top Of Zone 2 Aligns With LT1
- The top of Zone 2 aligns reasonably well with the first lactate threshold (LT1).
- The bottom of Zone 2 lacks consensus and scientists prefer the broader 'moderate intensity' domain.
Use RPE And Heart-Rate Drift To Find Zone
- Use Rate of Perceived Exertion to find LT1: it's commonly about a 5/10 effort at threshold.
- Keep easy runs at ~2–4/10 RPE and watch heart-rate stability over an hour as a validation.