⏱️ Time: 3-4 hr/week | 🎯 Difficulty: Intermediate | 📈 ROI: Compound Gain | ✅ Status: Active
Zone 2 Training
Build more mitochondria. Burn more fat. Live longer.
Time: 3-4 hours/week | Difficulty: Easy to do, hard to stick with
Why It Works
Zone 2 is the intensity where you burn fat efficiently and build mitochondrial density (San-Millán & Brooks, 2018):
- More mitochondria — More cellular energy capacity
- Better lactate clearance — Higher ceiling for intense work later
- Improved insulin sensitivity — Better metabolic health (Attia, 2023)
Both San Millán and Seiler agree: ~80% of training volume should be Zone 2 (San-Millán & Brooks, 2018; Seiler, 2010). Elite endurance athletes know this. Most recreational exercisers don’t.
How To Find Your Zone 2
No lactate meter? Use these:
- Talk Test (best): You can hold a conversation, but you’d rather not. Can’t sing.
- RPE: 3-4 out of 10. Feels easy. Sustainable for hours.
- Heart Rate: 70-80% max HR, or 180 minus your age. HR is noisy—trust the talk test first.
The Protocol
Frequency: 3-4 sessions/week Duration: 45 min minimum. 60-90 min ideal. Mitochondrial adaptation needs sustained stress.
Short on time? 3×45 min beats 2×60 min. Have time? 4×60 min is better.
Best modalities:
- ✅ Stationary bike / trainer (easiest to control)
- ✅ Incline walking / rucking
- ✅ Rowing (if technique allows low HR)
- ⚠️ Running (often spikes HR too high for beginners)
Progression
Don’t increase intensity. Zone 2 is a biological state, not a performance target.
Progress by increasing the wattage or speed required to stay in Zone 2. That’s fitness improving.
Common Mistakes
Drifting into Zone 3: Feels productive. Isn’t. Too hard for mitochondria, too easy for VO2max. The “grey zone” wastes time.
Boredom: This training is unsexy. Audiobooks and podcasts help. The benefit is cellular, not psychological.
Linked Concepts
- Resistance Training (The other 20% of the equation)