Zone 2 cardio for longevity: how much, how often, and why
The minimum effective dose, how to find your zone 2 threshold without lab testing, and what the endurance data shows.
Why zone 2 specifically
Zone 2 training targets your aerobic base: the intensity at which your mitochondria can fully oxidize fat for fuel without accumulating lactate. This is significant for longevity because mitochondrial function is one of the hallmarks of aging, and zone 2 is the most efficient stimulus for mitochondrial biogenesis in slow-twitch muscle fibers.
Peter Attia, Inigo San Millan, and other longevity-focused practitioners have popularized this zone because it specifically addresses the metabolic decline that accelerates aging.
Finding your zone 2 without a lab
The gold standard is a lactate threshold test (blood lactate stays below 2 mmol/L). Most people do not need this. Practical methods:
The talk test: You can hold a conversation but it requires effort. If you can chat effortlessly, you are too easy. If you can only get out a few words, you are too hard.
Heart rate estimate: Roughly 60 to 70 percent of your max heart rate for most people. The MAF formula (180 minus age) is a reasonable starting point, though individual variation is significant.
Rate of perceived exertion: 3 to 4 out of 10. It should feel sustainable for hours, not minutes.
How much is enough
The current evidence and expert consensus converges on 3 to 4 sessions per week, 45 to 60 minutes each. This totals 150 to 240 minutes of zone 2 per week.
This aligns with (and slightly exceeds) the WHO physical activity guidelines, but the emphasis on staying in zone 2 specifically is what differentiates this from generic “get 150 minutes of moderate exercise” advice.
Common mistakes
The most common error is going too hard. Most people default to zone 3 or 4 when they think they are doing zone 2. This is counterproductive: higher intensity shifts fuel utilization toward glycolysis and away from fat oxidation, reducing the mitochondrial stimulus.
The second mistake is inconsistency. Mitochondrial adaptations require regular stimulus. Three sessions per week for 12 months beats five sessions per week for 8 weeks.
Bottom line
Zone 2 is the single highest-leverage exercise modality for longevity based on current evidence. The dose is 3 to 4 times per week, 45 to 60 minutes, at an intensity where you can talk but prefer not to. Start with walking if your current fitness is low. The modality matters less than the metabolic zone.