How much Zone 2 cardio should you do per week?

Across the panel the answer lands around 3-4 hours of Zone 2 per week, and it's one of our strongest consensus topics (4.6/5). Attia — by far the most authoritative voice, with 30+ videos and six episodes alongside mitochondrial physiologist Dr. Inigo San-Millan — does four sessions of 45-90 minutes each. Huberman targets 200 minutes a week (~3.3 hours). Hyman suggests 150-200 minutes. Johnson aims for 4.5 hours across Zones 2-4. Same ballpark, different bookkeeping.

Two rules the experts agree on matter more than the exact total. First, the 80/20 rule: roughly 80% of your cardio volume at easy Zone 2, 20% at high intensity (VO2 max / Zone 5). Second, session length: Attia says sessions should be at least 45 minutes to reach metabolic steady state, where the mitochondrial adaptations happen. If you're new, start with two 30-minute sessions and, after 8-12 weeks, add frequency before you add duration.

What is Zone 2? The gold-standard definition is the highest intensity you can sustain while keeping blood lactate below 2 mmol/L. Without a lactate meter, use the talk test (endorsed by Attia, Huberman, and Patrick): you can speak in full sentences but with noticeable strain. Most people train too hard for this — Attia's garbage zone, too hard to build an aerobic base, too easy to drive a real high-intensity stimulus. Why bother? Attia's headline data point: moving from below-average to above-average cardiorespiratory fitness is associated with a 41% lower all-cause mortality risk — outperforming blood pressure, BMI, and age as a predictor.