Heart Rate Zones Explained: How to Train in Each Zone
Learn what heart rate zones are, how to calculate them, and how training in each zone improves fat burn, endurance, and speed. Plus: Zone 2 training explained.
Steps Team•
Heart Rate Zones Explained: How to Train in Each Zone
Most people train by feel — pushing hard some days, taking it easy on others. But without understanding heart rate zones, you're leaving serious fitness gains on the table. Training in the right zone at the right time is the difference between building a stronger aerobic engine and spinning your wheels with fatigue.
Heart rate zones let you train smarter, not just harder. Whether you want to burn more fat, run a faster 5K, or simply live longer, matching your effort to the right zone is the most effective way to get there.
What Are Heart Rate Zones?
Heart rate zones divide your maximum heart rate into five ranges, each triggering different physiological adaptations. Higher zones mean more intensity, faster calorie burn, and greater cardiovascular demand — but they're not always better. The most powerful training happens when you target the right zone for your specific goal.
| Zone | % of Max HR | Name | Primary Benefit |
|---|---|---|---|
| Zone 1 | 50–60% | Active Recovery | Promotes recovery, blood flow |
| Zone 2 | 60–70% | Fat Burning / Aerobic Base | Fat oxidation, aerobic foundation |
| Zone 3 | 70–80% | Aerobic Endurance | Cardiovascular efficiency |
| Zone 4 | 80–90% | Threshold | Lactate clearance, speed |
| Zone 5 | 90–100% | Maximum Effort | Peak power, VO2 max |
Understanding which zone you're training in changes how you plan every workout and every recovery day.
How to Calculate Your Heart Rate Zones
The simplest way to find your zones starts with estimating your maximum heart rate (MHR):
Max HR = 220 - Age
For a 30-year-old: Max HR = 220 - 30 = 190 bpm
Their zones would be:
| Zone | % Max HR | BPM Range |
|---|---|---|
| Zone 1 | 50–60% | 95–114 bpm |
| Zone 2 | 60–70% | 114–133 bpm |
| Zone 3 | 70–80% | 133–152 bpm |
| Zone 4 | 80–90% | 152–171 bpm |
| Zone 5 | 90–100% | 171–190 bpm |
This formula gives a solid starting estimate. For higher accuracy, a lab-based VO2 max test or a field test (like a 20-minute all-out time trial) can better identify your true max HR.
Skip the manual math — use the Heart Rate Zones Calculator to instantly calculate all five zones based on your age and resting heart rate.
Zone 1 – Active Recovery (50–60%)
Zone 1 is your easiest effort — a comfortable walk or gentle cycle where you can hold a full conversation without any breathlessness. It might feel too easy to be useful, but that's exactly the point.
Training in Zone 1 promotes blood circulation to recovering muscles, clears metabolic waste, and reduces soreness after hard sessions. Elite endurance athletes use Zone 1 on their "off" days to stay active without accumulating fatigue.
Best for: Day-after recovery, warm-ups and cool-downs, active rest days between hard training blocks.
Zone 2 – Fat Burning and Aerobic Base (60–70%)
Zone 2 is where the most important long-term adaptations happen — and most recreational athletes spend almost no time here. At this intensity, your body primarily fuels itself with fat rather than carbohydrates, making it the optimal zone for body composition and metabolic health.
More importantly, Zone 2 is the foundation of endurance. It builds mitochondrial density — the number and efficiency of the "power plants" in your muscle cells. More mitochondria means your body produces energy more efficiently at all intensities, making you faster and more fatigue-resistant even in Zone 4 and Zone 5.
Zone 2 as a longevity hack: Researchers like Dr. Peter Attia have popularized Zone 2 training as one of the most evidence-backed interventions for metabolic health, cardiovascular longevity, and cognitive function. Aim for 3–4 hours of Zone 2 per week for maximum benefit.
How it feels: You can speak in full sentences, but a sustained conversation requires mild effort. If you can sing, you're in Zone 1. If you're struggling to form sentences, you've drifted into Zone 3.
Best for: Long runs, easy cycling, base-building phases, anyone focused on fat loss or long-term health.
Zone 3 – Aerobic Endurance (70–80%)
Zone 3 is often called the "grey zone" — it's harder than Zone 2 but not intense enough to produce the high-end adaptations of Zone 4. Many recreational runners spend too much time here: too hard to be easy, too easy to be hard.
That said, Zone 3 does build aerobic capacity and is appropriate for tempo efforts and moderate-length races. It develops your body's ability to sustain effort over longer distances and improves cardiac output.
How it feels: Conversational running becomes difficult — you can manage short sentences but not full dialogue.
Best for: Moderate tempo runs, aerobic capacity building, steady-state cardio sessions of 30–60 minutes.
Zone 4 – Threshold Training (80–90%)
Zone 4 sits at and just above your lactate threshold — the point where lactic acid begins accumulating faster than your body can clear it. Training here pushes that threshold upward, meaning you can sustain faster paces before "hitting the wall."
This is the zone of 5K and 10K race efforts, hard interval sessions, and threshold runs. It's uncomfortable but sustainable for roughly 20–40 minutes at full effort.
How it feels: Speech is limited to a few words at a time. You're working hard and aware of it.
Best for: Interval training, tempo runs, race-specific work, improving lactate threshold pace.
Zone 5 – Maximum Effort (90–100%)
Zone 5 is all-out effort — sprints, hill repeats, the final kick of a race. You cannot sustain this for more than 30–90 seconds. Training at Zone 5 develops VO2 max (your body's maximum oxygen-processing capacity), fast-twitch muscle recruitment, and raw speed.
These sessions are powerful but demanding. Most athletes should limit Zone 5 work to 1–2 sessions per week to allow full recovery.
How it feels: You cannot speak. Every system is at maximum output.
Best for: Sprint intervals, VO2 max development, speed work, peak fitness phases.
How to Use Heart Rate Zones in Your Training Week
The most evidence-backed approach for endurance athletes is the 80/20 rule: spend approximately 80% of training time in Zones 1–2 and 20% in Zones 3–5.
Here is a sample weekly training structure for a runner logging 5 sessions per week:
| Day | Session | Zone | Duration |
|---|---|---|---|
| Monday | Easy run | Zone 2 | 45 min |
| Tuesday | Interval session | Zone 4–5 | 40 min |
| Wednesday | Active recovery walk | Zone 1 | 30 min |
| Thursday | Tempo run | Zone 3–4 | 35 min |
| Friday | Rest or Zone 1 walk | Zone 1 | 30 min |
| Saturday | Long run | Zone 2 | 75–90 min |
| Sunday | Full rest | — | — |
The key principle: protect your easy days. If Zone 2 workouts drift into Zone 3 because you're running with a faster friend or chasing pace targets, you accumulate excess fatigue and miss the aerobic base benefit. Slow down and trust the process.
Use the Heart Rate Zones Calculator to find your exact bpm targets and build a training week around your numbers.
FAQ
What is Zone 2 heart rate?
Zone 2 is 60–70% of your maximum heart rate. For a 30-year-old with a max HR of 190 bpm, Zone 2 is roughly 114–133 bpm. It's the intensity where fat oxidation peaks and mitochondrial adaptations are maximized — the foundation of aerobic fitness.
How do I know if I'm in Zone 2?
The easiest test is the talk test: if you can speak in full, comfortable sentences without pausing to breathe, you're in Zone 2. If conversation requires effort or you're speaking in short bursts, you've moved into Zone 3. A heart rate monitor removes the guesswork entirely.
Should beginners train in Zone 2?
Yes — Zone 2 is ideal for beginners. It's sustainable, reduces injury risk, and builds the aerobic base that makes all higher-intensity training more effective. Most beginners actually need to slow down more than they think to stay in Zone 2.
How do heart rate zones change with age?
As you age, your maximum heart rate decreases (roughly 1 bpm per year after age 20). This means your absolute bpm targets for each zone decrease too, even though the percentages stay the same. A 50-year-old has a max HR of approximately 170 bpm, making their Zone 2 target 102–119 bpm — significantly lower than a 25-year-old's.
What's the difference between Zone 3 and Zone 4?
Zone 3 (70–80% max HR) is below your lactate threshold — you can sustain it for 60+ minutes. Zone 4 (80–90% max HR) is at or above the lactate threshold, where lactic acid accumulates and sustainable duration drops to 20–40 minutes. Zone 4 produces greater fitness adaptations but requires longer recovery.
Ready to train smarter? Use the free Heart Rate Zones Calculator on Steps to calculate your personalized zones instantly — then download the Steps app to track your daily activity and build the aerobic base that every fitness goal depends on.