Heart rate training has taken over the running world and for good reason. By training within specific heart rate zones, runners can improve endurance, speed, recovery, and even long-term health.

These are the 5 Zones:

• Zone 1: Easy warm-up or recovery pace

• Zone 2: Low-intensity aerobic work

• Zone 3: Moderate, steady-state

• Zone 4: Threshold effort

• Zone 5: All-out sprint

In this article, we’re diving into the golden zone for endurance, fat-burning, and long-term progress: Zone 2. You’ll learn what it is, why it works, how to train in it, and how often it should be used depending on your goals.

What is Zone 2 Running?

Zone 2 running refers to low-intensity, aerobic-paced running—typically performed at around 60–70% of your maximum heart rate. It’s a pace where your body primarily uses oxygen and fat as fuel, rather than relying on glycogen or anaerobic energy systems. This makes it ideal for improving long-term endurance and efficiency.

Calculating Your Max Heart Rate

Basic Formula: 220 – age

This is the most commonly used formula, though it’s only a rough estimate and can be off by ±10–15 bpm for some people.

More Refined Formula (Tanaka): 208 – (0.7 × age)

Developed from a large population study, it tends to be slightly more accurate than the 220 formula.

Lab or Field Testing (Most Accurate):

If you want true accuracy, a VO2 max test or a max effort field test (like a graded treadmill test or running intervals until exhaustion with a heart rate monitor) is best.

How to ensure you are in Zone 2 while running?

There are three simple ways to make sure you’re in Zone 2:

• Watch Heart Rate: Your watch displays that you are between 60–70% of your HRmax.

• Talk Test: You should be able to hold a conversation without gasping.

• RPE Scale: On a scale of 1–10, it should feel like a 3 or 4—easy but intentional.

Why Zone 2 Running will make you faster

Zone 2 running may feel slow, but it’s how you get faster in the long run. Here’s why:

• Builds a Bigger Aerobic Engine - Over 90% of your race-day energy comes from your aerobic system. Zone 2 strengthens that engine.

• Increases Mitochondrial Density - More mitochondria = more energy production = less fatigue.

• Improves Fat Metabolism - You’ll burn fat more efficiently and preserve glycogen for when you really need it.

• Lowers Your Heart Rate at Faster Paces - Over time, your pace gets quicker without your heart rate rising.

Other Benefits

Running isn’t everything in life (even though sometimes it feels like it), so here are some non-running-related benefits of zone 2 running

1. Stronger Heart - Lowers resting heart rate and blood pressure, reducing the risk of heart disease.

2. Better Brain & Mood - Boosts mental clarity, reduces anxiety, and supports emotional balance.

3. Improved Sleep - Promotes deeper, more restful sleep by lowering stress hormones.

4. More Energy - Enhances cellular energy production and reduces fatigue throughout the day.

5. Fat Burning - Trains your body to burn fat more efficiently, supporting lean body composition.

6. Reduced Stress - Activates the parasympathetic nervous system, helping you stay calm and recover better.

How Often? 80/20 Approach

A good rule of thumb is to follow the 80/20 principle 

80% of your runs should be in Zone 2, with the remaining 20% at higher intensities (tempo, intervals, hills). Zone 2 runs have a low impact on the body, allowing you to push harder on your higher intensity days while continuing to improve your aerobic base.

Zone 2 Guidelines for Different Race Distances

As previously mentioned, the 80/20 split is a general guideline, and your goal distance will impact how much Zone 2 running is recommended. Here are some more rough guidelines for popular race distances:

• 🏃‍♂️ 5K/10K: 70% Zone 2, plus more interval work.

• 🏃‍♀️ Half Marathon: Mostly Zone 2, with tempo sessions added in.

• 🏔️ Marathon/Ultra: 85–90% Zone 2 to prepare for long efforts.

No matter the distance, Zone 2 is always the foundation. Without it, speed and stamina hit a ceiling, which is why it still makes up the bulk of training even for short races.

Conclusion: Run Slow and Build Your Engine

Zone 2 running is where long-term progress lives. It’s not exciting, but it is effective.

So don’t be afraid to slow down. Because if you stay consistent, trust the process, and build your aerobic base, you’ll go farther and faster than ever before.

If you learnt something new or just enjoyed the article, forward it to a friend who trains too.

Thanks for Reading

Oli