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Summary
Heart rate training zones divide your effort range into five intensity bands, each targeting different physiological adaptations. Zone 1 is light recovery work; Zone 5 is all-out effort. The zones are calculated as percentages of your estimated maximum heart rate (MHR), using either a simple percentage or the Karvonen method which personalises the zones using your resting heart rate.
The 5-zone model is the most widely used framework in endurance sports (Seiler & Kjerland, 2006) and aligns with the American Heart Association (AHA) and American College of Sports Medicine (ACSM) intensity classifications.
How it works
- Estimate your maximum heart rate — using either the Tanaka formula (more accurate) or the traditional 220 − age formula
- Choose a zone method — percentage of max HR (simpler) or Karvonen/heart rate reserve (more personalised)
- Calculate zone boundaries — apply the chosen method to map each zone’s percentage range into actual BPM values
The formulas
Maximum heart rate estimation
Tanaka formula (recommended):
Where
Based on a meta-analysis of 351 studies with 18,712 participants (Tanaka et al., 2001, JACC). More accurate than the traditional formula across all age groups, especially for older adults. Gender and habitual physical activity level do not significantly affect the equation.
Traditional formula (Fox et al., 1971):
Where
Widely cited but less accurate. Tends to overestimate max HR in younger people and underestimate it in older adults.
Zone calculation: percentage of max HR
Where
Simple and requires only your age. Does not account for individual fitness level.
Zone calculation: Karvonen (heart rate reserve)
Where
Uses your resting heart rate to personalise zone boundaries. A fitter person (lower resting HR) gets wider zones and lower Zone 1 boundaries. Recommended by the ACSM for exercise prescription because it correlates more closely with %VO₂max (Karvonen et al., 1957).
The 5-zone model
| Zone | Name | % Range | Effort | Description |
|---|---|---|---|---|
| 1 | Recovery | 50–60% | Very light | Warm-up, cool-down, active recovery. Full conversation possible. |
| 2 | Fat Burn | 60–70% | Light–moderate | Steady runs, walks, easy cycling. Sentences easily spoken. |
| 3 | Aerobic | 70–80% | Moderate | Tempo runs, steady cycling. Short sentences only. |
| 4 | Threshold | 80–90% | Hard | Interval training, fast running. Only a few words at a time. |
| 5 | Maximum | 90–100% | All-out | Sprints, max power. Cannot speak. Short bursts only. |
The percentage ranges are the same whether using the percentage-of-max or Karvonen method — what changes is how those percentages map to BPM values.
Worked examples
Example 1: Percentage method
30-year-old, Tanaka formula, percentage of max HR
Max HR (Tanaka)
= 187 bpm
Zone 1 (50–60%)
= 94–112 bpm
Zone 2 (60–70%)
= 112–131 bpm
Zone 3 (70–80%)
= 131–150 bpm
Zone 4 (80–90%)
= 150–168 bpm
Zone 5 (90–100%)
= 168–187 bpm
Result
5 contiguous zones from 94 bpm (Zone 1 low) to 187 bpm (max HR)
Example 2: Karvonen method
30-year-old, resting HR 60, traditional formula, Karvonen method
Max HR (traditional)
= 190 bpm
Heart rate reserve
= HRR = 130 bpm
Zone 1 (50–60% HRR)
= 125–138 bpm
Zone 2 (60–70% HRR)
= 138–151 bpm
Zone 3 (70–80% HRR)
= 151–164 bpm
Zone 4 (80–90% HRR)
= 164–177 bpm
Zone 5 (90–100% HRR)
= 177–190 bpm
Result
Karvonen zones start higher (125 vs 95 bpm for Zone 1) because resting HR raises the floor
Measuring resting heart rate
Measure first thing in the morning, before getting out of bed, on 3 consecutive days. Average the readings.
- NHS normal range: 60–100 bpm for adults
- Trained athletes: 40–60 bpm is common
- A lower resting heart rate generally indicates better cardiovascular fitness
Assumptions & limitations
- Max HR is an estimate. Both formulas predict population averages with a standard deviation of approximately ±10 bpm. The only way to know your true max HR is a supervised maximal exercise test.
- Individual variation is significant. Two 30-year-olds can have max HRs differing by 20+ bpm. Zone boundaries should be treated as guidelines, not hard thresholds.
- The 5-zone model is a simplification. Physiological transitions (aerobic threshold, lactate threshold) don’t fall neatly at round percentage boundaries. Lab-based lactate testing provides more precise individual thresholds.
- Resting HR varies day to day. Stress, sleep, hydration, caffeine, and illness all affect resting heart rate. Measure consistently for the best Karvonen results.
- Not suitable for certain medical conditions. People on beta-blockers or with cardiac conditions should consult their doctor, as these medications directly affect heart rate response.
Verification
| Test case | Method | Max HR | Zone 1 | Zone 3 | Zone 5 | Source |
|---|---|---|---|---|---|---|
| Age 30, Tanaka, %MHR | Percentage | 187 | 94–112 | 131–150 | 168–187 | Manual calc |
| Age 30, Trad, Karv, RHR=60 | Karvonen | 190 | 125–138 | 151–164 | 177–190 | calculator.net |
| Age 45, Trad, Karv, RHR=70 | Karvonen | 175 | 123–133 | 144–154 | 165–175 | Manual calc |
All values cross-checked against calculator.net and manual calculation of the Tanaka/Fox and Karvonen formulas.
Sources
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