Training zones
for running
Learn to train at the right intensity to improve faster.
What are the training zones?
They are five intensity bands, usually defined as a percentage of maximum heart rate: Z1 recovery (50–60%), Z2 aerobic (60–70%), Z3 tempo (70–80%), Z4 threshold (80–90%) and Z5 VO2max (90–100%). Each zone trains a different system — from fat burning in Z2 to maximal aerobic power in Z5.
Each zone develops different physiological capacities
50-60% · Very easy
Recovery
Active recovery, walking or very light jogging
60-70% · Easy
Aerobic
Conversational pace, training foundation
70-80% · Moderate
Tempo
Sustained pace, aerobic threshold
80-90% · Hard
Threshold
Anaerobic threshold, 10K-half marathon race pace
90-100% · Maximum
VO2max
Intense intervals, sprints
Worked example: the zones in bpm.
For a runner with a measured max heart rate of 185 bpm, the bands look like this. Swap in your real value: the 220 − age formula is only a rough estimate.
| Zone | Name | % of max HR | bpm (max HR 185) | Feel |
|---|---|---|---|---|
| Z1 | Recovery | 50–60% | 93–111 | Very easy |
| Z2 | Aerobic | 60–70% | 111–130 | Easy |
| Z3 | Tempo | 70–80% | 130–148 | Moderate |
| Z4 | Threshold | 80–90% | 148–167 | Hard |
| Z5 | VO2max | 90–100% | 167–185 | Maximum |
Why 80% of training should be easy?
Because low intensity is where the body builds its aerobic base — more mitochondria, more capillaries, a more efficient heart — with little fatigue. Stephen Seiler's studies of elite athletes show about 80% of sessions easy and 20% hard; that distribution is what lets you run the quality sessions with quality.
Zone 2 is where the magic of aerobic development happens
Cardiac efficiency
Strengthens the heart and increases the volume of blood pumped per beat
Fat burning
Teaches the body to use fat as fuel, sparing glycogen
Mitochondrial density
Increases the number of mitochondria, improving energy production
Base for intensity
A strong aerobic base enables more efficient quality workouts
The 80/20 rule: 80% easy, 20% intense
Used by the world's best endurance athletes
Heart rate or pace: which to use?
Use heart rate on easy and long runs, because it reflects heat, sleep and fatigue; use pace on quality sessions and races, because it responds instantly and is what the watch controls best. When in doubt, heart rate sets the ceiling for easy and pace sets the target for hard.
Both have their place in training. Know when to use each one.
Heart Rate
Accounts for external factors (heat, stress, fatigue). Ideal for easy and long runs. Prevents overtraining.
Best for: Easy runs, long runs, recovery
Pace
Immediate feedback, ideal for quality workouts. Easy to control during races.
Best for: Intervals, tempo runs, races
How to calculate your zones?
Start from your real max heart rate — the highest reading in a 5K race or an exertion test, not the 220 − age formula — and apply each zone's percentages. If you have a recent race time, use the magic calculator: it converts the result into a Magic Index and returns the pace for each zone.
Different methods to find your ideal zones
By Max HR
Use your actual max HR (from a test or race) and apply each zone's percentages
By Anaerobic Threshold
More accurate. Use your threshold HR (30min all-out test) as reference
By Magic Index
Based on your recent race time. Our calculator does this automatically
By Perceived Effort
Z2 = can hold a conversation. Z4 = can say 2-3 words. Z5 = can't speak
Which mistakes to avoid?
The four most common: living in Z3 (too hard to recover from, too easy to improve), running easy days too fast, ignoring heart rate on hot days and never recalculating your zones. If you can't hold a conversation on an easy run, you're going too fast — that simple.
Always training in Z3
The 'gray zone' develops neither speed nor base. Too intense to recover from, too easy to improve.
Running easy too fast
If you can't hold a conversation, you're going too fast. Z2 should be truly easy!
Ignoring HR on hot days
In the heat, respect your HR even if pace drops. Internal effort is what matters.
Not recalculating zones
Your zones change as you improve. Recalculate every 2-3 months or after races.
Frequently asked questions.
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