Compare your Zone 2 aerobic threshold range side-by-side across four sports-science formulas (Karvonen 60-70% Heart Rate Reserve, Joe Friel’s 81-89% Lactate Threshold HR, Tanaka %HRmax, and Maffetone 180-Age) and split your weekly cardio minutes 80/20 between easy and hard work, the pattern Stephen Seiler described in endurance athletes.
Core Equation & Guard-Rail
Karvonen Z2 = RHR + 0.60–0.70 × (HRmax − RHR) · LTHR Z2 = 0.81–0.89 × LTHR · Tanaka HRmax = 208 − 0.7 × Age
Fixed percentage-of-max zones can sit well away from where your first ventilatory threshold actually is, especially for very fit athletes with low resting heart rates. Anchoring to heart rate reserve or lactate threshold heart rate often lines up better with the talk test. These are estimates: if you have a heart condition or take medication that affects heart rate, ask your doctor which numbers suit you.
136 – 150 bpm
Consensus LT1 band
192 mins/wk
Zone 1–2 aerobic base
48 mins/wk
Threshold & VO2max
| Physiological Model | Zone 2 Range [EST] | Why It Differs |
|---|---|---|
| Karvonen Heart Rate Reserve (60–70% HRR) | 133 – 146 bpm | Accounts for your resting heart rate reserve |
| Lactate Threshold 80/20 (81–89% LTHR) | 139 – 153 bpm | Anchored to your 20-30 min threshold effort |
| Standard %HRmax (65–75% Max HR) | 121 – 140 bpm | Default watch formula (often underestimates fit athletes) |
| Maffetone MAF (180 − Age) | 138 – 148 bpm | Maffetone’s conservative rule of thumb |
Heart rate zones are estimates. If you have a heart condition or take medication that affects heart rate, ask your doctor which numbers suit you.
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Karvonen Z2 = RHR + 0.60–0.70 × (HRmax − RHR) · LTHR Z2 = 0.81–0.89 × LTHR · Tanaka HRmax = 208 − 0.7 × Age
Fixed percentage-of-max zones can sit well away from where your first ventilatory threshold actually is, especially for very fit athletes with low resting heart rates. Anchoring to heart rate reserve or lactate threshold heart rate often lines up better with the talk test. These are estimates: if you have a heart condition or take medication that affects heart rate, ask your doctor which numbers suit you.
General fitness and training estimates only, labelled EST. Not medical advice or a clinical diagnosis.
Verified Literature
When a lab or field max heart rate is unavailable, the regression 208 minus 0.7 times age gives a better group-level estimate for healthy adults than the older 220 minus age rule. Individuals can sit well away from it.
Tanaka, H., Monahan, K.D. & Seals, D.R. "Age-predicted maximal heart rate revisited." Journal of the American College of Cardiology, 2001;37(1):153-156. doi:10.1016/s0735-1097(00)01054-8
View the sourceSuccessful endurance athletes in this review spent roughly 80 per cent of their sessions at low intensity (below the first lactate threshold) and about 20 per cent at high intensity, a pattern many coaches use as a sensible default.
Seiler, S. "What is best practice for training intensity and duration distribution in endurance athletes?" International Journal of Sports Physiology and Performance, 2010;5(3):276-291. doi:10.1123/ijspp.5.3.276
View the sourceYour VO2max estimate from a hard run comes straight from Daniels' VDOT tables, the pace-to-fitness model coaches have trusted for over forty years.
Daniels, J. Daniels' Running Formula, 4th edition. Champaign, IL: Human Kinetics, 2021. ISBN 9781718203662, 320 pp. Carries forward the VDOT tables and the velocity-to-oxygen-cost regressions first published in Daniels, J. & Gilbert, J. Oxygen Power: Performance Tables for Distance Runners, Tempe, AZ, 1979.
View the sourceDeep-Dive Training Guides
Automatic Tracking & Adaptation
Inside Pelaris, you never need to punch numbers into a spreadsheet. Every logged set, run and check-in updates your estimates automatically and adapts next week’s sessions.
Cardio & Endurance
Race Time Predictor
Predict 5K, 10K, Half Marathon and Marathon finish times and splits using Riegel’s power law and Pelaris’s 0.5x to 2.0x distance guard-rail.
Cardio & Endurance
VO2max & Fitness Age Calculator
Estimate VO2max from any run using Daniels VDOT, see your peer percentile in the FRIEND registry, and get a fitness age estimate plus your training paces.
Standard %HRmax ignores your resting heart rate and lactate threshold. An athlete with a 48 bpm resting heart rate and a high lactate threshold has a much wider aerobic reserve than a sedentary adult of the same age, which Karvonen HRR and LTHR capture.
Use the talk test (a practical stand-in for the first ventilatory threshold): at the top of Zone 2 you can still speak in full sentences without gasping, though your listener can tell you are exercising.
Stephen Seiler’s (2010) review describes how successful endurance athletes train: roughly 80 per cent of sessions at low intensity and 20 per cent at high intensity. It describes what many elite athletes do rather than proving it is the only way to improve, and it is a good default for most people.