Zone 2 Training: The ‘Slow’ approach to fast results

Most runners make the same mistake I did for years: running every session at the same moderate-to-hard pace. It feels productive. You’re sweating, breathing hard, and covering distance. But you’re actually limiting your potential.

Enter Zone 2 training.

What is Zone 2?

Zone 2 is typically defined as 60-70% of your maximum heart rate. For most people, this means running at a conversational pace—slow enough that you could hold a conversation without gasping for air.

It feels almost too easy. And that’s exactly the point.

The Science Behind It

When you run in Zone 2, you’re training your aerobic energy system. This leads to:

  • Increased mitochondrial density: More cellular powerhouses = more energy production
  • Better fat oxidation: Your body becomes more efficient at burning fat for fuel
  • Improved capillary development: More blood flow to working muscles
  • Faster recovery: Lower stress on your body allows for more consistent training

The Software Engineering Parallel

This reminds me of paying down technical debt. You could keep pushing features out quickly (“running hard every day”), but you’re building up fatigue in the system. Eventually, things break.

Taking time to refactor, write tests, and improve your codebase (“Zone 2 work”) feels slow and unproductive in the moment. But it builds a foundation that allows you to move faster later.

My Zone 2 Protocol

  • 80% of my weekly running miles are in Zone 2
  • I wear a heart rate monitor to keep myself honest
  • I swallow my ego when faster runners pass me
  • The remaining 20% includes speed work and tempo runs

Results After 6 Months

  • Average easy pace improved by 45 seconds/km
  • Resting heart rate dropped from 58 to 48 bpm
  • Marathon PR improved by 12 minutes
  • Fewer injuries and faster recovery between sessions

Start Slow to Go Fast

The next time you lace up your shoes, try slowing down. Way down. Your future self will thank you.

And the same goes for your codebase.

What’s your training philosophy? Are you a Zone 2 convert or still skeptical? Let me know!