Zone 2 Aerobic Training

Physiology

• Predominantly slow-twitch (Type I) fibre recruitment.
• Fat oxidation is the dominant fuel source (vs carbohydrate at higher intensities).
• Mitochondrial biogenesis is preferentially stimulated at Zone 2 durations.
• Improves lactate-clearance capacity independent of increasing peak power.

How to find your Zone 2

• Talk test: full conversational sentences without breathlessness.
• Heart rate: ~65–75% of max (rough approximation).
• Lactate: 1.7–2.0 mmol/L (gold standard, requires finger-prick during exercise).
• Nose breathing: sustainable nose-only breathing.

Dose

• 150–240 minutes/week for most longevity purposes.
• Attia advocates 3–4 hours/week for well-trained older adults.
• Modality flexible: cycling, rowing, incline walking, elliptical.

Longevity relevance

VO₂max is a stronger mortality predictor than most blood biomarkers. Zone 2 training is one of the two levers (with HIIT) to raise it.

More on this topic

• GDF-15 — Biomarker.
• Mitobridge (acquired by Astellas) — Company.
• Stealth BioTherapeutics — Company.
• SOD2 — Gene.
• Coenzyme Q10 (Ubiquinone / Ubiquinol) — Intervention.

Related entries

Exercise, VO2max, Zone 2 vs HIIT, Mitochondrial dysfunction.