What is Zone 2 Training?
Zone 2 is the aerobic training intensity where your body primarily burns fat for fuel while building mitochondrial density. It's the foundation of endurance fitness and is characterized by:
Zone 2 Indicators
- Can breathe through nose only
- Can hold a full conversation
- Feels "easy" to sustainable
- 60-70% of max heart rate
- RPE 3-4 out of 10
Zone 2 Benefits
- Maximizes fat oxidation
- Builds mitochondrial density
- Improves aerobic base
- Low injury risk
- Fast recovery between sessions
Zone 2 Heart Rate by Age (Complete Chart)
| Age | Max HR | Zone 2 Low (60%) | Zone 2 High (70%) | MAF (180-age) |
|---|---|---|---|---|
| 20 | 200 | 120 | 140 | 160 |
| 25 | 195 | 117 | 137 | 155 |
| 30 | 190 | 114 | 133 | 150 |
| 35 | 185 | 111 | 130 | 145 |
| 40 | 180 | 108 | 126 | 140 |
| 45 | 175 | 105 | 123 | 135 |
| 50 | 170 | 102 | 119 | 130 |
| 55 | 165 | 99 | 116 | 125 |
| 60 | 160 | 96 | 112 | 120 |
| 65 | 155 | 93 | 109 | 115 |
| 70 | 150 | 90 | 105 | 110 |
* Max HR calculated using 220-age formula. For more accuracy, use the Karvonen method with your actual resting heart rate.
Zone 2 Calculation Methods
1. MAF Formula (Dr. Phil Maffetone)
Adjustments:
- Subtract 10: Recovering from major illness or injury
- Subtract 5: Inconsistent training or frequent colds
- No change: Training consistently for up to 2 years
- Add 5: Training consistently 2+ years without injuries
Example: 40-year-old consistent runner: 180 - 40 = 140 bpm ceiling
2. Percentage of Max HR (Standard)
Example: 40-year-old: Max HR = 180, Zone 2 = 108-126 bpm
Note: The 220-age formula can be inaccurate by ±10-12 bpm. If you know your actual max HR from testing, use that instead.
3. Karvonen Formula (Heart Rate Reserve)
Example: Max HR 180, Resting HR 60:
Low: ((180-60) × 0.60) + 60 = 132 bpm
High: ((180-60) × 0.70) + 60 = 144 bpm
The Karvonen method is more accurate because it accounts for individual fitness levels through resting heart rate.
Zone 2 by Age and Resting Heart Rate (Karvonen)
| Age | RHR 50 | RHR 60 | RHR 70 | |||
|---|---|---|---|---|---|---|
| 60% | 70% | 60% | 70% | 60% | 70% | |
| 30 | 134 | 148 | 138 | 151 | 142 | 154 |
| 35 | 131 | 145 | 135 | 148 | 139 | 151 |
| 40 | 128 | 141 | 132 | 144 | 136 | 147 |
| 45 | 125 | 138 | 129 | 141 | 133 | 144 |
| 50 | 122 | 134 | 126 | 137 | 130 | 140 |
| 55 | 119 | 131 | 123 | 134 | 127 | 137 |
| 60 | 116 | 127 | 120 | 130 | 124 | 133 |
RHR = Resting Heart Rate. Measure your resting HR first thing in the morning before getting out of bed.
Get Your Personalized Zone 2
Use our Zone 2 Calculator for precise heart rate zones using MAF, Karvonen, and 3 other proven formulas.
Open Zone 2 CalculatorHow to Train in Zone 2
Duration
45-90 minutes per session. The aerobic adaptations require sustained effort. Start with 30-45 minutes if new to Zone 2.
Frequency
3-4 sessions per week. Elite endurance athletes do 4-6 hours of Zone 2 weekly. Start with 2-3 hours total.
Activities
Running, cycling, swimming, rowing, hiking. Any sustained cardio works. Mix activities to reduce injury risk.
Pacing
Slow down on hills to stay in zone. Walk if needed. Zone 2 often feels "too easy" - that's correct!
The Talk Test
If you can't hold a conversation or need to breathe through your mouth, you're above Zone 2. Slow down until you can speak in full sentences comfortably.
Common Zone 2 Training Mistakes
Going Too Fast
The #1 mistake. Zone 2 should feel easy. If your ego says slow down, listen to it. Many people's "easy" pace is actually Zone 3-4.
Too Short
Zone 2 benefits require time. A 20-minute Zone 2 run provides minimal aerobic benefit. Aim for 45+ minutes.
Inconsistency
Zone 2 benefits compound over weeks and months. One session per week won't build your aerobic base. Aim for 3-4 weekly.
Using Wrong HR Zones
Generic watch zones are often wrong. Calculate your personal zones using the formulas above, or use the Karvonen method for best accuracy.