Heart rate zones group intensity into bands so cardio sessions are repeatable and fatigue is easier to manage.
01Deriving zones
| Method | Core assumption | Practical boundary |
|---|
| Max heart rate formula | Max HR is stable across tests | Age-based formulas are rough, validate with talk test or a field test |
| Field test estimate | Zone boundaries shift with fitness and fatigue | Re-check every 4 to 6 weeks or after a training block |
| Talk-breath method | Conversation pace maps to intensity | Useful when sensor signal is noisy |
02Zone map
| Zone | % of max HR band | Primary use |
|---|
| Z1 | 50 to 60 | Recovery and active movement days |
| Z2 | 60 to 70 | Endurance base and aerobic conditioning sessions |
| Z3 | 70 to 80 | Tempo and VO2 max support work |
| Z4 | 80 to 90 | Threshold and hard controlled intervals |
| Z5 | 90 to 100 | Very hard peaks and short repeated efforts |
03Aerobic base and threshold templates
| Template | Target pattern | Core cue |
|---|
| Aerobic base block | 45 minutes at Z2 with one short Z3 finisher | Keep breathing steady, no sustained zone spikes |
| Threshold block | 6 to 8 rounds of 3 to 4 minutes in Z4 with 2-minute float | Keep form quality above pace in each work interval |
| Recovery drift block | 25 minutes in Z1 with walk-to-jog transitions | Use when sleep and soreness stack up |
04Invalidation rules
| Signal | Why invalidate zone target | Action |
|---|
| Caffeine, alcohol, or sleep debt | Resting HR drift raises baseline | Shift effort by one zone down for the session |
| Illness signs or fever | HR can overstate effort load | Replace with recovery template and note for review |
| Dehydration or heat load | HR stays high while output falls | Reduce load, hydrate, and revalidate when stable |
| Bad strap contact or sensor gap | Data artifact can mimic fatigue | Cross-check with rate of perceived effort and rerun warm-up check |
Use VO2 max, interval training, wearable metrics, and calorie-burn estimation so energy and recovery logic remain linked.
