Heart Rate Zones

Five training zones based on percentage of max heart rate, each targeting different physiological adaptations.

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Understanding Heart Rate Zones

Heart rate zones divide your exercise intensity into five ranges based on percentage of maximum heart rate. Each zone targets different physiological systems: Zone 1 (50–60%) for recovery, Zone 2 (60–70%) for aerobic base, Zone 3 (70–80%) for aerobic endurance, Zone 4 (80–90%) for lactate threshold, and Zone 5 (90–100%) for VO2 max.

Training by heart rate zones ensures you're working at the right intensity for each workout's purpose. Most runners train too hard on easy days and too easy on hard days — heart rate monitoring fixes this by providing objective intensity feedback. The "80/20 rule" recommends 80% of training in Zones 1–2 and only 20% in Zones 3–5.

Setting accurate zones requires knowing your maximum heart rate. The "220 minus age" formula is a rough estimate with wide individual variation (±10–15 beats). Better methods: a lab test, a field test (sustained max effort hill run), or using the heart rate from the final mile of a hard 5K race as an approximation of max HR.

Key Facts: Heart Rate Zones

Key facts and insights about heart rate zones that every endurance athlete should know.

Five zones

Five zones: Z1 (recovery), Z2 (aerobic), Z3 (tempo), Z4 (threshold), Z5 (VO2 max)

The 80/20 rule

The 80/20 rule: 80% of training in Zones 1–2, 20% in Zones 3–5

"220 minus age" for max HR is only an es

"220 minus age" for max HR is only an estimate — individual variation is ±10–15 bpm

Heart rate lags 30–60 seconds behind eff

Heart rate lags 30–60 seconds behind effort changes (cardiac drift)

Pro Tips: Heart Rate Zones

Determine your max heart rate from a real effort (race or field test), not a formula

Use heart rate for easy runs (to keep truly easy) and pace for workouts (HR responds too slowly for intervals)

Don't panic about day-to-day HR variation — look at weekly trends

If your easy-run heart rate is creeping up over several days, you may be under-recovered

Frequently Asked Questions About Heart Rate Zones

Common causes: heat (HR rises 5–10 bpm in warm weather), dehydration, poor sleep, stress, caffeine, illness coming on, or accumulated training fatigue. One high-HR easy run is normal. Multiple in a row suggests you need more recovery.

Both, for different purposes. Heart rate is best for controlling easy-run intensity (keeping you honest about "easy"). Pace is better for intervals and tempo runs where you need specific speed targets and HR lags behind effort. Most experienced runners use HR for easy runs and pace for workouts.