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What Is "Zone 2 Training"? Experts' Viewpoint on Definition, Training Methods, and Expected Adaptations

Multiple international experts (2025) International Journal of Sports Physiology and Performance
zone-2-cardio endurance training
Title and abstract of What Is

Key Takeaway

Expert consensus defines Zone 2 as just below LT1/VT1, with blood lactate ~1-2 mmol/L and HR at 70-80% max.

Summary

This 2025 expert consensus paper provides standardized definitions for Zone 2 training:

  • Intensity: Just below LT1/VT1
  • Blood lactate: ~1-2 mmol/L
  • Heart rate: 70-80% of max
  • RPE: ~10 on 6-20 Borg scale

Related Studies

What is Best Practice for Training Intensity and Duration Distribution in Endurance Athletes? (2010) Zone 2 Intensity: A Critical Comparison of Individual Variability in Different Submaximal Exercise Intensity Boundaries. (2025) Comparison of Polarized Versus Other Types of Endurance Training Intensity Distribution on Athletes' Endurance Performance: A Systematic Review with Meta-analysis. (2024) Much Ado About Zone 2: A Narrative Review Assessing the Efficacy of Zone 2 Training for Improving Mitochondrial Capacity (2025)

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The Art of Manliness
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The Longevity Link
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The Proof with Simon Hill
Science of zone 2 cardiovascular exercise | Inigo San Millan, PhD The Proof with Simon Hill

Source

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