What is Zone 2 heart rate training?
Zone 2 is the second of five heart rate training zones, typically defined as 60–70% of your maximum heart rate. It represents an effort level that's clearly above a casual stroll but far below a hard workout — the kind of pace where you can hold a full conversation without gasping.
In physiological terms, Zone 2 is the upper limit of purely aerobic metabolism, where your body primarily uses fat as fuel and can sustain effort almost indefinitely without accumulating lactate. It's also known as the aerobic threshold zone or "easy" zone in training terminology.
Here's how all five zones compare:
Find your exact Zone 2 heart rate range — enter your age and resting HR for a personalised result.
Zone 2 Calculator →Why Zone 2 training matters
Zone 2 has gained enormous attention from endurance athletes and longevity researchers because of its unique combination of physiological benefits:
Mitochondrial development
Zone 2 is the primary driver of mitochondrial biogenesis — the creation of new mitochondria in muscle cells. Mitochondria are the powerhouses that convert oxygen and fuel into usable energy. More mitochondria means greater aerobic capacity, better fat oxidation, and faster recovery. This is the foundation of everything else.
Fat oxidation
At Zone 2 intensity, fat is the dominant fuel source. Zone 2 training teaches your body to burn fat more efficiently — which matters for endurance performance, body composition, and metabolic health. Higher-intensity exercise burns more calories per minute but shifts toward carbohydrate as fuel; Zone 2 uniquely maximises the fat-burning pathway.
Cardiovascular efficiency
Consistent Zone 2 work increases stroke volume — the amount of blood your heart pumps per beat. This is the primary adaptation that allows trained athletes to do more work at a lower heart rate. As stroke volume improves, your heart becomes more efficient and your resting heart rate drops.
Lactate clearance capacity
Training at Zone 2 improves your body's ability to clear lactate from the bloodstream, raising the threshold at which lactate begins to accumulate. This directly improves performance at all higher intensities — you can sustain harder efforts for longer before fatiguing.
Longevity and metabolic health
VO2 max — which is largely built through aerobic base training — is one of the strongest predictors of long-term health and all-cause mortality. Regular Zone 2 training also improves insulin sensitivity and metabolic flexibility, which are central to metabolic health and disease prevention.
How to calculate your Zone 2 heart rate
There are two main methods, ranging from simple estimates to more personalised calculations.
Method 1: Percentage of max HR (simple)
Zone 2 = 60–70% of your maximum heart rate. Estimate your max HR using: 220 − your age.
| Age | Est. Max HR | Zone 2 Range (60–70%) |
|---|---|---|
| 25 | 195 bpm | 117–137 bpm |
| 30 | 190 bpm | 114–133 bpm |
| 35 | 185 bpm | 111–130 bpm |
| 40 | 180 bpm | 108–126 bpm |
| 45 | 175 bpm | 105–123 bpm |
| 50 | 170 bpm | 102–119 bpm |
| 55 | 165 bpm | 99–116 bpm |
| 60 | 160 bpm | 96–112 bpm |
Method 2: Karvonen formula (more accurate)
This method accounts for your resting heart rate, making zones more personalised to your fitness level:
Zone 2 = Resting HR + (Heart Rate Reserve × 60–70%)
Heart Rate Reserve (HRR) = Max HR − Resting HR
Example: Age 40, resting HR 65 bpm. Max HR = 180. HRR = 115. Zone 2 = 65 + (115 × 0.60) to 65 + (115 × 0.70) = 134–146 bpm.
Notice how the Karvonen result (134–146) is higher than the simple method (108–126) for the same person. The Karvonen formula gives a more accurate personalised range, especially for people with lower resting heart rates from good aerobic fitness.
The talk test: check Zone 2 without any device
In Zone 2, you should be able to speak in complete sentences without pausing for breath. If you're gasping mid-sentence, you're too hard. If you could easily sing, you're too easy. This simple test closely tracks the physiological Zone 2 threshold and is used by elite coaches as a real-time check.
How to actually stay in Zone 2 during workouts
The biggest challenge for beginners is that Zone 2 feels uncomfortably slow. Here's how to make it work in practice:
Use a heart rate monitor
You cannot reliably gauge Zone 2 by perceived effort alone, especially as a beginner. A chest strap monitor (Polar H10, Garmin HRM-Pro) is the most accurate option. Wrist-based optical monitors on smartwatches are acceptable for steady-state Zone 2 training but less reliable during movement intensity changes.
Accept that you'll need to slow down
This is the most important thing to understand: most beginners need to walk or power-walk to stay in Zone 2. This is not a failure — it's your current aerobic base. Within 6–12 weeks of consistent training, your pace at Zone 2 heart rate will improve noticeably. Many experienced runners are surprised to find they can run at a 9-minute mile in Zone 2 after 6 months of base training versus needing to walk at first.
Choose the right activities
Some activities are naturally better suited to Zone 2 training:
- Cycling (indoor or outdoor): Easiest to control intensity precisely. Flat terrain or a smart trainer allows stable Zone 2 maintenance.
- Running: Effective but harder for beginners due to terrain and pace variability causing heart rate spikes. Many new runners need to run-walk to stay in Zone 2.
- Rowing: Excellent full-body Zone 2 option. Steady-state rowing at moderate resistance keeps heart rate consistent.
- Swimming: Effective, but note that heart rate runs 10–15 bpm lower in water — adjust your target range downward accordingly.
- Brisk walking: For deconditioned beginners, brisk walking is a completely valid Zone 2 workout and should not be dismissed.
Warm up properly
Heart rate takes time to stabilise. Allow 5–10 minutes of easy movement before targeting your Zone 2 range. Starting a session in Zone 2 immediately after sitting down will result in an artificially low heart rate that then spikes — making the session harder to manage.
How much Zone 2 training should you do?
For general fitness and health benefits, aim for 150–180 minutes of Zone 2 per week — roughly 3 sessions of 45–60 minutes. This aligns with research on aerobic adaptations and meets cardiovascular health guidelines.
Endurance athletes typically follow an 80/20 approach: approximately 80% of total weekly training volume in Zone 2, with 20% in higher zones. For recreational fitness, a simpler approach works: most cardio in Zone 2, with one or two harder sessions per week if desired.
Beginner Zone 2 progression (first 12 weeks)
Weeks 1–4: 3 × 30-minute sessions. Focus on staying in zone, even if that means walking. Total: 90 min/week.
Weeks 5–8: 3 × 40–45 minutes. Pace will have started to improve. Total: 120–135 min/week.
Weeks 9–12: 3–4 × 45–60 minutes. Aerobic base clearly building. Total: 135–240 min/week.
Zone 2 and weight loss
Zone 2 is often promoted as the "fat burning zone" — and while there's truth to this, the relationship with weight loss is more nuanced.
Zone 2 maximises the percentage of calories burned from fat during exercise (roughly 50–60% of calories burned are from fat in Zone 2 versus less in higher zones). However, higher-intensity exercise burns more total calories per unit of time.
For weight loss, Zone 2's real advantages are: it's sustainable for longer sessions (more total calories burned), it improves metabolic flexibility over time, it's recoverable enough to do frequently, and it doesn't drive the post-exercise appetite increases that high-intensity training can. For practical fat loss, Zone 2 works best when combined with a modest calorie deficit.
Calculate your full 5-zone heart rate training ranges, including Zone 2.
Full Heart Rate Zones →Zone 2 training after 40
Maximum heart rate declines with age (roughly 1 bpm per year), which shifts Zone 2 absolute bpm targets downward. A 50-year-old has a lower Zone 2 ceiling than a 30-year-old — this is normal and expected.
For people over 40, Zone 2 becomes increasingly important. Aerobic capacity naturally begins to decline from the mid-30s onward, and regular Zone 2 training is one of the best-evidenced strategies for maintaining VO2 max and cardiovascular health through middle age and beyond. It also supports insulin sensitivity, which is increasingly important with age.
Women over 40 should also consider how hormonal changes (perimenopause and menopause) affect recovery and training response. Zone 2's low intensity means it's generally well-tolerated regardless of hormonal fluctuations, making it a reliable anchor for fitness training through this life stage.
Combining Zone 2 with strength training
Zone 2 and resistance training complement each other effectively. Zone 2 builds cardiovascular capacity and improves fat metabolism; strength training builds and preserves lean muscle mass — which itself improves metabolic rate and long-term health.
For combining both: most people perform better doing strength training before Zone 2 (not after), as Zone 2 pre-fatigues the cardiovascular system and can reduce strength performance. Separating them into different days is ideal when scheduling allows. The combination is particularly powerful for body composition and is recommended for most adults over 35.
Common Zone 2 mistakes
- Training in Zone 3 ("grey zone"): Most people naturally gravitate to a moderate effort too hard for true Zone 2 but not intense enough to be a proper hard session. This grey zone delivers less benefit than either Zone 2 or genuinely high-intensity training. If your heart rate is sitting at 72–78% max HR, slow down.
- Sessions that are too short: Sessions under 30 minutes produce minimal Zone 2 adaptation. The mitochondrial stimulus requires sustained aerobic stress. Aim for minimum 40 minutes per session for meaningful adaptation.
- Going by feel rather than data: Zone 2 almost always feels easier than people expect. Most people who train "easy" without monitoring are actually in Zone 3. Use a heart rate monitor.
- Not recalculating zones over time: As fitness improves, your Zone 2 pace increases and your resting heart rate drops. Recalculate your zones every 8–12 weeks or when you notice your resting HR has dropped by 5+ bpm.
- Expecting quick dramatic results: Zone 2 builds slowly. The adaptations — mitochondrial density, stroke volume, fat oxidation — take months to fully develop. Commit to a 12-week minimum before evaluating.