Heart-Rate Zones (5-Zone Model)
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A common scheme that divides aerobic intensity into five heart-rate bands (zone 1 easy to zone 5 maximal), used to structure and distribute training.
Detail
The 5-zone model splits training intensity into five heart-rate bands, usually expressed as percentages of maximal heart rate (HRmax) or of heart-rate reserve (HRR; see karvonen-hrr). A widely used percent-HRmax version is:
| Zone | Name | %HRmax (typical) | Feel |
|---|---|---|---|
| 1 | Very light / recovery | 50–60% | Very easy, fully conversational |
| 2 | Light / endurance | 60–70% | Easy, conversational (aerobic base) |
| 3 | Moderate / tempo | 70–80% | Comfortably hard, short phrases |
| 4 | Hard / threshold | 80–90% | Hard, talking difficult |
| 5 | Maximal / VO2max | 90–100% | Near-maximal to maximal |
These percentage boundaries are conventions and approximations. The physiologically meaningful zone borders are the metabolic thresholds: the boundary near zones 1–2/3 corresponds roughly to the first lactate/ventilatory threshold (LT1/VT1), and the zone 4/5 region corresponds to the second threshold (LT2/VT2) (see lactate-threshold and ventilatory-thresholds). Because individuals' thresholds fall at different heart-rate percentages, zones anchored to measured thresholds (or to lactate/breathing cues) are more individualized than fixed-percentage zones.
Different zone systems exist (3-zone, 5-zone, 7-zone power systems), and exact band edges vary by source, so zones should be treated as a practical framework rather than precise biological lines. The model underpins training-distribution strategies such as polarized and pyramidal training (see training-intensity-distribution).
Key facts
- Five bands by %HRmax (typical): Z1 50–60, Z2 60–70, Z3 70–80, Z4 80–90, Z5 90–100.
- Can equivalently be built on %HRR (Karvonen) instead of %HRmax.
- Zone borders ≈ metabolic thresholds: ~Z2/3 ≈ LT1/VT1; ~Z4/5 ≈ LT2/VT2.
- Percentage edges are conventions; threshold-anchored zones are more individualized.
- Multiple systems exist (3/5/7 zones); exact cutoffs vary by source.
Connections
- karvonen-hrr — building zones from heart-rate reserve.
- percent-hrmax — the %HRmax basis used above.
- lactate-threshold / ventilatory-thresholds — the real zone borders.
- zone-2-training — the aerobic-base zone in detail.
- target-heart-rate — guideline-side target-zone content.
- hrmax-calculation — supplies HRmax (220 − age).
Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.