If you follow Peter Attia — physician, longevity researcher, and host of The Drive podcast — you've heard him talk about Zone 2 more times than you can count. He's called it the single most important type of exercise for long-term health and longevity.
But here's the gap most people hit: Attia's protocol is more specific than people realize, and almost no fitness app is actually built to support it.
Here's what Attia actually recommends — and how to implement it in the real world.
Volume: 3–4 hours per week, spread across 4 sessions of 45–60 minutes
Intensity: Just below your first lactate threshold (LT1) — blood lactate ~1.7–2.0 mmol/L
Modality: Cycling, incline walking, rowing — anything sustainable at low intensity
Timeframe: Months to years of consistent training — not a short-term phase
Attia is emphatic about one thing: most people think they're doing Zone 2 and they're not.
They're in Zone 3 — the metabolic grey zone that's too easy to drive VO2max adaptations and too hard to be truly aerobic. It feels productive. You're sweating. Your Garmin says "Zone 2." But you're not getting the mitochondrial density and fat oxidation improvements that make Zone 2 so valuable.
His preferred test for true Zone 2: you should be able to hold a full conversation. Not just say a word or two — a real back-and-forth. If speaking requires effort, you've gone too hard.
There's a specific failure mode Attia calls out repeatedly, and it affects the majority of people who think they're doing Zone 2: they're actually in Zone 3.
Zone 3 is the metabolic grey zone. It's too hard to be truly aerobic — you're generating enough lactate to accumulate fatigue — but too easy to drive the VO2max adaptations you'd get from real high-intensity intervals. It feels productive. You're sweating, your heart is working, your fitness tracker shows you burning calories. But you're not building the mitochondrial density that makes Zone 2 so valuable, and you're not training your ceiling. You're just grinding.
How do you know you're in Zone 3? You can speak, but only in short bursts. A full sentence requires a pause. Your breathing is labored. You feel like you're working. That's the tell.
True Zone 2 feels different: you could hold a normal conversation. You could go for another hour. You should feel almost embarrassed by how easy it is. That discomfort — the ego resistance to going slow — is one of the biggest barriers to actually implementing Attia's protocol correctly.
Standard fitness apps — including Apple's built-in zones — use the 220-minus-age formula to estimate max heart rate and divide zones by percentage. This produces a generic Zone 2 range that can be off by 10–20 bpm for any given individual.
Even if you nail your max heart rate, static percentage-based zones don't account for the day-to-day variation in your aerobic threshold. Your LT1 on a well-rested Tuesday is different from your LT1 after a bad night of sleep or a stressful week. A fixed number doesn't flex with you.
What Attia's protocol actually requires is a dynamic, feedback-informed system that helps you stay below LT1 — not a static heart rate ceiling.
Implement Attia's protocol without a lab. Zone2AI gives you adaptive, personalized Zone 2 zones on Apple Watch — free to start.
Try Zone2AI Free →If you can access a lactate test, do it. Many sports medicine clinics and performance labs offer them for $150–$300. It's the most accurate option.
If not, use the talk test as a proxy. Find the sustainable pace where you can speak in complete, comfortable sentences. Note your heart rate. Back off a few beats from there — that's your working Zone 2 target.
Cycling and incline walking are Attia's top recommendations for most people because they're easier to sustain at low intensity without cardiovascular drift. Running works well for trained runners but tends to push newer runners above Zone 2 without realizing it.
3–4 hours per week is the target. Four 45-minute sessions, or three 60-minute sessions. This is where the adaptations happen — below that volume, you're maintaining rather than improving.
This is where Zone2AI comes in. Rather than locking you into a static heart rate range, Zone2AI's AI coach adapts to your training feedback over time. After each session, it refines your personal Zone 2 window based on how the effort felt — getting closer and closer to what a lactate test would reveal.
For people following Attia's protocol who don't have access to a lab, Zone2AI is the closest practical equivalent: a personalized, adaptive Zone 2 target that improves with every workout. It works on Apple Watch, free to start.
Attia talks about Zone 2 as a years-long investment. Track your resting heart rate, your pace-at-Zone-2-effort, and your energy levels over time. The signal that you're making progress: your pace at a fixed Zone 2 heart rate should increase over months.
Most people see meaningful improvement within 3–4 months of consistent, properly-dosed Zone 2 training:
Peter Attia's Zone 2 protocol is specific, evidence-based, and genuinely transformative for long-term health — but only if you're actually doing Zone 2 and not the generic-formula approximation that most apps serve up.
The gap between "what apps call Zone 2" and "what Attia means by Zone 2" is where most people's results disappear.
Close that gap with accurate, personalized zones. Use the talk test. Consider a lactate test if you're serious. And use tools that adapt to you — not a formula written for someone else.
Zone2AI was built around Attia's framework — adaptive zones that learn your physiology, not a static formula. Available on Apple Watch.
Download Zone2AI →Disclaimer: This post is for informational purposes. Always consult a healthcare provider before starting a new exercise program, especially if you have cardiovascular concerns.