How to Use Heart Rate Zones

Dated caveat. The Tanaka 2001 HRmax formula remains the least-biased age-based estimator as of 2026^[2]. Athlete-specific formulas^[5] narrow the error further for trained cohorts, but none supersede Tanaka at the general-population level.

Step 1: Estimate HRmax

Three options, in order of accuracy:

1. Field test: thorough warm-up followed by a progressive all-out 3–6 minute effort, peak HR observed. Most accurate, requires willingness to go hard.
2. Tanaka formula: 208 − 0.7 × age. RMSE ~±7 bpm against lab-measured values.
3. Observed max from a recent hard session: if your HR monitor has shown 189 bpm during a hard interval, your HRmax is at least 189.

Age     220 − age    Tanaka (208 − 0.7 × age)
 25       195            191
 35       185            184
 45       175            177
 55       165            170

The old 220 − age formula systematically underestimates HRmax in older adults. Tanaka is the defensible default^[2].

Step 2: Measure HRrest properly

Karvonen-based zones need an accurate resting HR. Protocol:

• On waking, before standing up or moving much.
• Before caffeine.
• Count for 60 seconds (not 15 × 4 — too noisy).
• Average across 5–7 consecutive mornings.

Typical HRrest ranges:

Sedentary adult             70–85 bpm
Active non-athlete          60–75 bpm
Recreational endurance      50–65 bpm
Competitive endurance       40–55 bpm
Elite endurance             35–45 bpm

If you're measuring HRrest with a chest strap while sitting quietly, that's fine. A wrist-based optical sensor can read 3–5 bpm high at true rest; re-test with palpation for calibration.

The Resting Heart Rate Calculator averages a 7-day input and flags meaningful drift.

Step 3: Compute Karvonen zones

HRR = HRmax − HRrest

Target HR for a given zone = HRrest + (zone_pct × HRR)

Example: 35-year-old, Tanaka HRmax = 184, HRrest = 55
  HRR = 184 − 55 = 129

Zone 1 (recovery, 50–60% HRR):   55 + 0.50×129 to 55 + 0.60×129    =  120–132
Zone 2 (aerobic, 60–70% HRR):    55 + 0.60×129 to 55 + 0.70×129    =  132–145
Zone 3 (tempo, 70–80% HRR):      55 + 0.70×129 to 55 + 0.80×129    =  145–158
Zone 4 (threshold, 80–90% HRR):  55 + 0.80×129 to 55 + 0.90×129    =  158–171
Zone 5 (VO2 max, 90–100% HRR):   55 + 0.90×129 to 184              =  171–184

The Heart Rate Zone Calculator produces this table automatically and lets you compare it side-by-side with percent-HRmax zones.

Zone definitions

• Zone 1 — Recovery. Conversational, nose-breathing easy. Active recovery, warm-ups.
• Zone 2 — Aerobic base. Still conversational but steady. Fat oxidation dominant. This is where long slow runs live.
• Zone 3 — Tempo. Speak in short phrases. Between LT1 and LT2. Useful but over-used; most recreational runners live here by accident.
• Zone 4 — Threshold. At or just above LT2. Hard but sustainable for 30–60 minutes with training. Threshold work sits here.
• Zone 5 — VO2 max. Above threshold, sustainable for 3–10 minutes per bout. Interval work.

Common errors

• Using 220 − age for HRmax. Biased by 5–10 bpm in either direction depending on age.
• Using a guessed HRrest. “Probably around 60” isn't enough; measure for a week.
• Confusing percent-HRmax and Karvonen zones. 70% HRmax and 70% HRR are different numbers. Pick one system and stick with it.
• Chasing zones on days when HR is drifted. Heat, illness, poor sleep all push HR up at a given workload. If the HR number conflicts with RPE, listen to RPE.

HR vs power vs pace

For disciplines with external work metrics, HR-based zones have trade-offs against direct work-output measurement:

Metric       Pro                                      Con
─────────────────────────────────────────────────────────────────────────────
HR            Integrates internal load                 Lags effort; drifts
              Works across disciplines                 Affected by external conditions
Pace           Precise, external work metric            Terrain and weather sensitive
              Instantly responsive                     Biased by elevation
Power (bike)   Exact instantaneous work output          Requires power meter
              Insensitive to conditions                Cycling-specific

For running, the defensible default is HR for long aerobic work and pace for intervals and race efforts. For cycling, power is near-universally better than HR if you have the equipment.

Using zone bands during intervals

During interval sessions, the HR target is the lower bound of the target zone, not the upper bound. An interval at “Zone 5” should push HR to at least 90% HRmax by the end of the interval — it's fine if it climbs into the 95%+ range on the last interval. The purpose is to spend time at high aerobic intensity; reaching the zone is the work.

For threshold work in Zone 4, stay within the middle of the zone — drifting into Zone 5 means you've overcooked the pace and the interval is now a different session type.

Zone 2 as a specific case

In Karvonen, Zone 2 is 60–70% HRR. In percent-HRmax systems, it's 65–75% HRmax. The two roughly agree for average-fitness adults and can disagree by 10–15 bpm for very fit athletes with low HRrest. The Zone 2 Heart Rate Calculator uses Karvonen HRR with Tanaka HRmax — the more conservative combination — to set a Zone 2 upper bound you can actually train at without drifting higher.

Lactate-threshold-based zones

For serious endurance training, LT-anchored zones are a cleaner system than age-based HRmax zones. See the pillar article Heart Rate Zones: Methods Compared for the full comparison. If you have access to lab lactate testing or can run a defensible 20-minute time-trial, anchoring on your LTHR is worth the effort.

When HR isn't the right metric

• Sprints and lifting. HR lags the actual effort; a maximal 30-second sprint may only drive HR to Zone 4 because the anaerobic component dominates.
• Very short intervals. Same issue — HR doesn't have time to climb.
• Heat and altitude. HR is elevated at the same workload; pacing by HR alone under-delivers work.
• First few minutes of any session. HR ramps; don't chase the zone number in the first 5 minutes.

Worked example: 42-year-old recreational runner, end-to-end

Field-tested HRmax 178 (observed during a 5-min progressive running test after full warmup). Seven-day palpated morning HRrest 51. Apply the Karvonen 1957 method^[1]:

HRR = 178 − 51 = 127

Zone 1 (50–60% HRR): 115–127  Recovery runs, warm-up
Zone 2 (60–70% HRR): 127–140  Long slow runs, base building
Zone 3 (70–80% HRR): 140–153  Tempo (use sparingly)
Zone 4 (80–90% HRR): 153–165  Threshold intervals
Zone 5 (90–100% HRR):165–178  VO2 max work

Percent-HRmax version (for comparison)
Zone 2 (65–75% HRmax): 116–134
  Gap:  11 bpm lower at upper bound vs Karvonen

For a trained runner with a HRrest 20 bpm below population average, the percent-HRmax zones read systematically lower than Karvonen — which matches ACSM's 2021 guidance favouring HRR-based zones in fit populations^[3]. Running long-slow runs to the percent-HRmax Zone 2 cap (134 bpm) would under-dose the aerobic stimulus; Karvonen's 140 bpm cap is the defensible upper bound for the same athlete.

Common failure modes

• Fixing a zone error into a drift. An under-read HRrest (guessed 65 instead of measured 51) pushes every zone 7–8 bpm high. The athlete trains "Zone 2" above LT1 and accumulates grey-zone fatigue without aerobic-base returns.
• Ignoring heat drift. At 28°C ambient, HR at the same running pace runs 5–12 bpm higher than at 15°C. A zone system anchored on cool-weather HRmax pegs summer threshold runs into Zone 5 territory — stop pacing by HR when the gap exceeds ~7 bpm and defer to pace or RPE.
• Chasing zones in the first five minutes. HR takes 3–6 minutes to reach steady state at a new workload. Pacing aggressively against the zone number before HR catches up is how tempo runs turn into threshold runs.
• Trusting optical wrist-HR at high intensities. Optical sensors commonly disagree with chest-strap ECG by 8–15 bpm during Zone 4–5 work. For interval prescription, cross-validate against a chest strap on the first few sessions.

Connects to

• Heart Rate Zones: Methods Compared — the full comparison of zone systems.
• Zone 2 Training: What the Literature Says — why the aerobic zone gets most of your volume.
• How to Improve VO2 Max — where the upper zones get used.

Tools: Heart Rate Zone Calculator, Zone 2 Heart Rate Calculator, Resting Heart Rate Calculator.