What Needs to Shift?

Imagine you're handed a car with a full tank of gas, but there's a catch—the engine burns fuel so inefficiently, you barely make it down the street before needing to refuel. This is how most people's metabolism works.  ⚠️

Your body's ability to process oxygen (measured by VO₂ max) is like your engine's maximum horsepower—one of our best predictors of longevity. But here's the key: raw horsepower means nothing if your engine can't efficiently deliver fuel. 🛠️

Your body needs three things to produce energy efficiently:

• Pristine blood vessels to deliver oxygen and nutrients (think fuel lines)

• Efficient mitochondria to convert that oxygen into energy (think engines)

• The ability to use different fuel sources (think hybrid capability)

Fortunately, there’s a training zone that acts like a master switch, optimizing all these systems simultaneously—referred to as Zone 2. 🎯

What is Zone 2?

Zone 2 refers to a specific level of exercise intensity where your body can work steadily without building up fatigue. Think of it as one of several 'gears' your body can work in — each with different levels of effort and different effects on your body.

For practical purposes, your exercise intensity is in Zone 2 is when you can still talk but it would feel slightly laboured to do so, typically around 60-75% of your maximum heart rate.

It doesn’t matter which exercise you choose— jogging, cycling, or power walking. What matters is maintaining one steady pace without spikes or rests, like a cross-country road trip on cruise control versus stop-and-go city driving. Your engine hums at one efficient speed, and your body gets the message: "If we're doing this for a while, we better build better systems." 🚗

This steady effort builds the foundation you need to eventually push your VO₂ max higher—like establishing a solid fuel delivery system before upgrading your engine's horsepower. 🏎️

The Cellular Renovation Project

When you train in Zone 2, your body develops certain adaptations:

1) Metabolic Flexibility: Your Hybrid Engine ⚡

Your body primarily runs on two types of fuel: glucose and fat. (We’ll ignore ketones for now).

Think of glucose as premium gas. It burns fast and hot, perfect for quick energy.

Fat is like regular fuel; not as explosive, but you have a much larger supply. ⛽

Metabolic flexibility is your body’s ability to switch between these fuels efficiently. The problem? Most people are stuck in “glucose-burner” mode. 🚨

This creates a vicious cycle:

• The more glucose-dependent your system is, the worse your body gets at burning fat 🔥

• Your body demands more frequent meals for glucose because it can’t tap into fat efficiently ⚡

• Over time, insulin resistance develops, seeding the early stages of diabetes and trapping even more fat in storage 🔒

Zone 2 training breaks this cycle, teaching your metabolism to burn fat efficiently—like upgrading from a gas-only engine to a hybrid. The outcome is more stable energy and healthier aging.

2) Metabolic Efficiency: More Miles Per Gallon 🔋

Inside every cell, your mitochondria are like tiny power plants. When they're efficient, they produce clean energy. When they're not, they're like old engines spewing exhaust—and that exhaust accelerates aging.

Think of aging mitochondria like an engine that's gone 200,000 miles without maintenance. It still runs, but it burns more fuel, produces more waste, and delivers less power with each passing year.

But Zone 2 training triggers two powerful adaptations:

• Your existing mitochondria learn to burn more efficiently—producing more energy with less waste ♻️

• Your body also builds new mitochondria—like adding fresh engines to your aging fleet 📈⚡

3) Oxygen Delivery: Your Body’s Traffic Problem 🚦

Picture your circulation system like a city's delivery network. Your major arteries are the highways, but your capillaries—the tiniest blood vessels—are the neighbourhood streets where packages actually reach their destination (your cells). 🚚

You can have great highways (arteries), but if they feed into only a few local streets (capillaries), packages don’t get delivered or picked up on time. 🚧

In most people, these local routes (capillaries) are like a growing city that neglected to upgrade infrastructure. Therefore, your tissues age faster as oxygen-starved cells struggle with backed-up cellular waste. 🧹

Zone 2 training is your body's infrastructure upgrade plan, building new delivery routes that transform a congested city into a model of efficient flow.

This isn't just exercise—it's education for your metabolism. Each steady mile teaches your cells a new language of efficiency and resilience. The result? Your cellular machinery evolves from a fuel-wasting relic into a reliable hybrid engine.

Your Next Move

Pick Your Activity ✅

🚶‍♂️ Start With Brisk Walking (Recommended for Most)

• Most beginners can't run or bicycle slowly enough to stay in Zone 2

• Confession: When I started, even my slowest jog pushed my heart rate too high 😅

• The solution? A brisk walk — either on a treadmill at 5% incline or outside on a route with minimal stops and intersections (parks work well) 🌳

  • No excuses. Anyone can do this! 🙌🏽

🏃‍♂️ Graduate to Running or Cycling

• Once your metabolism adapts, running and cycling become excellent options

• The key? No stops, no sprints, just one smooth, continuous effort

Finding Your Zone 2 Pace 🎯

There are two ways to to find your Zone 2 pace:

🗣️ The Talk Test (Most Reliable)

• You're at the right pace when you can speak in full sentences, but it feel annoying to do so 😠

• If you're comfortable enough to sing your favourite song, you need to pick up the pace 🎵

• If you're gasping between words, dial it back 😮‍💨

• The “talk test” is more reliable at identifying Zone 2 than your smartwatch⌚

💓 Heart Rate Guide (Backup Method)

• Find your target heart rate range using this simple formula:

  • 180 minus your age = upper limit

    • Subtract 10 from that = lower limit

  • Example: if you’re 40-years old, aim for a heart rate between 130-140

• From there, focus on finding the pace that keeps you in this heart rate range

• Important: Your watch may label this range as a different "zone" — ignore these labels and focus on staying within your calculated numbers ⚠️

The key is to find the pace—whether walking, running, or cycling—that gets you into Zone 2. That pace will look different for everyone depending on their fitness level, but the talk test or heart rate ranges will guide you to your sweet spot. 

Need more guidance? Watch this video.

What "Steady" Really Looks Like

• It takes 5-10 minutes to reach your zone

• "Steady" doesn't mean "flat" — your heart rate naturally varies within a ~10 beat range

• Think of it like cruise control on your car — small fluctuations are normal while maintaining a steady average

Dial in Your Rhythm

Duration 📈

• 45-90 minutes per session ⏰

• Slow and long is the name of the game 🐢

• Perfect excuse to catch up on your Netflix or podcast queue 🎧🍿

Frequency 📊

• Start with 2 sessions per week—that's your minimum effective dose

• Once you're comfortable, aim for 3-4 sessions for optimal benefit

Still Unsure?

In this video, Dr. Peter Attia and Dr. Rhonda Patrick break down simple ways to figure out when you’re in Zone 2.