Training zones explained: what they are, how to find yours

A training zone is a band of effort somebody drew on a scale. Underneath the bands your body has two real boundaries, and every zone system is an attempt to describe them — with three bands, or five, or seven, measured against different anchors. That is why "zone 2" on your watch and "zone 2" in your plan can be fifty beats apart, and why both are used correctly.

Two boundaries, not five zones. Below the first you can keep going for hours. Above the second you have minutes. Everything interesting happens in the stretch between them.
The number of zones is a choice. Research usually uses three. Most watches use five. Coaches often use six or seven. One national team uses eight. None of them is wrong.
The anchor matters more than the count. A band set at a share of your maximum heart rate and a band set at a share of your threshold land in completely different places.
You can find your own at home, roughly. A hard thirty-minute effort, the point where sentences break up, and how hard it feels all aim at the same boundaries — each with a miss you can name.

Somebody tells you to do the run in zone 2. Your watch has a zone 2. Your training plan has a zone 2. A podcast has strong feelings about zone 2. And then you go out, settle into what feels easy, and the watch says you are in zone 3.

Nothing is broken. Those are different zone 2s, built by different people, measured against different numbers. Once you can see how a zone system is assembled, that stops being confusing and starts being useful — because you can tell which one you are being handed.

1 So what is a training zone?

A zone is a band on a scale, and somebody chose where the band starts and stops. TrainingPeaks, which sells the software a lot of coaches plan in, puts the recipe plainly: zone systems "pick a parameter (like heart rate, power, or pace) and use it to describe varying degrees of workout intensity as a percentage of a threshold."¹²

So there are three decisions behind any set of zones (figure 2). Which thing you measure. Which single number you measure it against — your maximum, or your threshold. And how many bands you cut the range into. Change any one of those and the same run lands in a different zone.

Three boxes with arrows between them. Box one, a parameter you can measure: heart rate, power in watts, pace or speed, how hard it feels. Box two, an anchor to compare it to: your maximum heart rate, your threshold heart rate, your threshold power, your threshold pace. Box three, how many bands to cut: three zones for research, five for most watches, six or seven for coaches, eight for some teams. — **Figure 2.** **The recipe.** Every zone system makes these three choices. Most of the confusion in this article comes from two systems making them differently and then using the same word for the result.

That is worth saying out loud because it changes what a zone is for. A zone is a way of agreeing what "easy" and "hard" mean, so that a coach, an app and a runner can talk about the same session. It is a unit of language before it is a unit of physiology.

Where these numbers come from: two of the sources on this page are practitioners rather than researchers — a watch maker and a coaching platform. We use them to establish what is being told to people, never to establish what works. Sources are marked T1 for research and T3 for practice, and the sources list at the bottom says which is which.

2 What is actually happening in your body?

Under all the models, your physiology offers two boundaries rather than five zones (figure 3).

As you speed up, there is a first point where something measurable changes: lactate in the blood starts rising above its resting level, and breathing steps up out of proportion to oxygen uptake. That is the first threshold, written VT1 or LT1 depending on whether it was spotted in the breath or the blood. There is a second point higher up where the disturbance stops being gradual and starts accelerating: VT2 or LT2.¹

A horizontal effort scale from easier to harder, split by two vertical lines labelled first threshold VT1 slash LT1 and second threshold VT2 slash LT2. Three bands: below the first threshold, you can hold this for hours, in green; between the two thresholds, sustainable but it builds up, in amber; above the second threshold, minutes not hours, in rust. — **Figure 3.** **The two boundaries.** The first threshold is where the effort first starts to cost you something. The second is where the cost starts compounding. Durations as reported by MacIntosh and colleagues.¹

Those two points carve the range into three stretches, and what separates them is time. Below the first threshold, exercise upsets very little and could be kept up for hours. Between the two, you are still supplying the energy aerobically, but the disturbance grows as you climb. Right at the second threshold, trained athletes typically last thirty to fifty minutes; the highest intensity at which blood lactate still holds steady can be sustained for forty to sixty minutes.¹ Above it, you are counting minutes.

This is the part that does not depend on anybody's model. Whether your app draws three bands or eight, it is drawing them around these two points — or around a proxy for them, which is where things get interesting.

3 Why does "zone 2" mean three different things?

Because the systems in daily use disagree about both the number of bands and what to measure them against (figure 4).

Research on how athletes distribute their training usually works in three: easy below the first threshold, moderate between the two, hard above the second.⁵ Most watches ship with five, cut as shares of your maximum heart rate — Polar publishes theirs as 50 to 60 per cent, 60 to 70, 70 to 80, 80 to 90 and 90 to 100.¹¹ The Norwegian Olympic Committee uses six for its endurance athletes.⁵ Joe Friel's running zones, the ones inside TrainingPeaks, run to seven and are cut as shares of your threshold heart rate rather than your maximum.¹² One national canoe team uses eight.⁵

Five horizontal bars stacked, each split into its zones and labelled. Three zones anchored on the two thresholds; five zones for most watches anchored on maximum heart rate; six zones on the Norwegian scale anchored on maximum heart rate; seven zones from Friel for running anchored on threshold heart rate; eight zones from one national team anchored on lactate and stroke rate. In each row the band that system calls zone 2 is outlined, and it sits in a different place along the scale. — **Figure 4.** **Five systems in use today.** The outlined band is the one each system calls zone 2. In the three-zone model it is the middle, working band; on a watch it is the second-easiest of five. Widths here are schematic — the point is the position.

Now put a real runner through three of them. Say her measured maximum heart rate is 190 and her threshold heart rate is 168. Those two numbers are a worked example rather than anybody's data, and the arithmetic below is ours — but the percentages are exactly as the three systems publish them.

Three horizontal bands on a heart-rate scale from 95 to 205 beats per minute, for one runner with a maximum of 190 and a threshold of 168. Polar's five-zone model, 60 to 70 per cent of maximum heart rate, gives 114 to 133 beats. Friel's seven-zone running model, 85 to 89 per cent of threshold heart rate, gives 143 to 150. The three-zone model used in research, 83 to 87 per cent of maximum, gives 158 to 165. A dashed line marks the threshold at 168. — **Figure 5.** **One runner, three zone 2s.** Polar's zone 2 comes out at 114 to 133 beats. Friel's running zone 2 at 143 to 150. The middle band of the three-zone research model at 158 to 165. **Our arithmetic** on the published percentages, using 190 and 168 as example anchors.

That is a fifty-beat span between the bottom of the easiest reading and the top of the hardest, all under one label. It also explains an argument you may have half-followed online. When researchers discuss "zone 2" they usually mean the working band between the two thresholds — brisk, sustainable, not easy. When a watch says zone 2 it usually means a genuinely gentle run. Both are being used correctly, and people talk past each other for hours.

The word tells you nothing until you know which system it came out of, and what that system measured against.

4 What does each band actually contain?

The clearest way to answer is to show a real scale rather than describe one (figure 6).

The six-zone scale the Norwegian Olympic Committee uses for its endurance athletes is a good one to look at, because it lines up four different measures for every band: a share of maximum heart rate, a share of maximum oxygen uptake, a blood lactate range, and a point on the six-to-twenty effort scale.⁵ Reading across a row shows you what a zone boundary is really made of.

A six-row table. Zone 1, easy: 60 to 72 per cent of maximum heart rate, 50 to 65 per cent of maximum oxygen uptake, under 1.5 millimoles per litre of blood lactate, 10 to 12 on the effort scale. Zone 2, easy: 73 to 82, 66 to 80, 1.5 to 2.5, 13 to 14. Zone 3, moderate: 83 to 87, 81 to 87, 2.5 to 4.0, 15 to 16. Zone 4, hard: 88 to 92, 88 to 93, 4.0 to 6.0, 17 to 18. Zone 5, hard: above 93, 94 to 100, 6.0 to 10.0, 18 to 19. Zone 6, hard: no heart rate or oxygen figure, above 10, 18 to 20. — **Figure 6.** **Inside the bands.** The Norwegian six-zone scale, as reported by Sun and colleagues.⁵ Note the top row: at the hardest efforts, heart rate and oxygen uptake stop being able to tell the zones apart, and only lactate and perceived effort still separate them.

Two things are worth noticing. First, in this scale the boundary between "easy" and "moderate" sits at around 2.5 millimoles per litre of lactate, and the boundary between "moderate" and "hard" at around 4.0 — which is roughly where the first and second thresholds are usually placed.⁵ The six bands are the three stretches from figure 3, subdivided.

Second, a caveat that belongs right beside the table: this is a scale for elite endurance athletes, and it says so. More on who these systems were built for in section 7.

What the bands do to you is a different question from what they contain, and a much noisier one. Claims like eighty per cent of your training should be easy and zone 2 has effects the other zones don't are arguments about training, not descriptions of a scale, and they deserve their own piece with the evidence laid out. We are working on it; this page stops at what the bands are.

5 Why does your watch disagree with your plan?

Usually for one of two reasons: it is using a different anchor, or it worked the anchor out for itself and got a different answer (figure 7).

The second one has been measured. Twenty-six runners did the threshold test built into a Garmin Fénix 7, then a standardised graded blood-lactate field test.⁴ The heart rate the watch put on the threshold was close to the lab-style figure — 1.71 per cent lower, a gap too small to show up in the statistics. The pace it put there was 11.87 kilometres an hour against 13.28 in the field test: nearly twelve per cent slow, and clearly more than noise.

Two panels. Left, pace at threshold: the blood-lactate field test gives 13.28 kilometres per hour, the Garmin Fenix 7 estimate 11.87, a difference of 11.96 per cent lower, big enough to show up in the statistics. Right, heart rate at threshold: the two numbers sat almost on top of each other, 1.71 per cent lower, too small to show up in the statistics. — **Figure 7.** **Watch against field test.** Twenty-six participants, seven women and nineteen men, average age twenty-six.⁴ One caveat belongs with this: it is one watch model in one study, so read it as an illustration of how these estimates behave rather than a number for your device.

The first reason is quieter, and it sits in the settings screen. Most watches build their default bands from your maximum heart rate, and most of them do not know it. Polar's own guidance for finding that number is "220 minus your age".¹¹ Friel's guidance is the opposite: "do not use 220 minus your age to find max heart rate as this is as likely to be wrong as right."¹²

Both of them are describing the same problem from different sides. That formula was never a research finding: it came from a 1971 review that plotted roughly thirty-five points and drew a line by eye, without a regression.¹⁰ The better-supported version, from a meta-analysis of 351 studies covering 18,712 people and cross-checked in a laboratory on 514 more, is 208 minus 0.7 times your age.⁹

A line chart of maximum heart rate against age from 20 to 80. A solid line for 208 minus 0.7 times age, a dashed line for 220 minus age, and a shaded band ten beats wide around the solid line showing the spread of individual values. The two lines cross around age 40 and are about ten beats apart by age 70. A note explains that a band set at 70 per cent of maximum moves about 7 beats for every 10 beats the estimate is wrong. — **Figure 8.** **The number your zones hang from.** Lines from Tanaka and colleagues.⁹ The shaded band is the reported scatter of individual maxima around the line, seven to eleven beats. The consequence for a zone edge is **our arithmetic**.

But the formula is not really the point; the cloud around it is. In that laboratory study, individual maxima scattered around the line with a spread of seven to eleven beats a minute.⁹ So two people the same age can genuinely have maxima ten beats apart, and every band drawn as a share of that estimate moves with it. At seventy per cent of maximum, a ten-beat error in the anchor shifts the edge of the band by about seven beats.

Worth adding, because it is the kind of thing that gets misremembered: the same study found the relationship was no different between men and women, and barely moved with how active people were.⁹ Age really is doing most of the work. It just does not do all of it for any particular person. If you want the longer version of how a watch arrives at any of its numbers, that is a separate piece.

6 How do you find your own without a lab?

Three routes are in common use, and each aims at a boundary rather than at a zone (figure 9).

A hard thirty-minute effort. Friel's method is to go hard and alone for thirty minutes, then take your average heart rate over the last twenty as an estimate of your threshold heart rate.¹² For power on the bike, the average over the whole thirty minutes estimates your functional threshold power. This is a practitioner's method rather than a validated protocol, which is exactly how it should be read — but it has the advantage of anchoring on something you produced rather than on a table.

The talk test. The idea is that where speech starts to break up tracks the first threshold, and where talking becomes genuinely hard tracks the second. In a crossover trial, nineteen participants rated their comfort talking on a one-to-ten scale during an incremental test: the power at a rating of 2 to 3 matched the power at the first ventilatory threshold to within about a watt, and a rating of 6 to 7 matched the second to within about eleven watts.⁸ One caveat sits right beside that: those nineteen people had a body mass index around 32 and were not athletes, so it tells you the method has a physiological basis rather than how well it works on a fit runner.

How hard it feels. Effort ratings track the boundaries too, and there is a large sample behind the anchor points: across 2,560 people, the average rating on the six-to-twenty scale was 10.8 at the boundary between moderate and vigorous, and 13.6 at the top of vigorous.¹ The spread is the interesting part. Each of those averages carried a standard deviation of 1.8, so a rating of 12 sits comfortably inside both.

Three cards. A 30-minute time trial, aiming at the second boundary: run or ride hard and alone for 30 minutes, the average heart rate over the last 20 is the estimate. The talk test, aiming at both boundaries: where full sentences break up sits close to the first boundary, where talking becomes really hard close to the second, tested mostly outside sport. How hard it feels, aiming at both roughly: on the 6 to 20 scale 2,560 people averaged 10.8 at the first boundary and 13.6 at the second, each average carrying a spread of plus or minus 1.8. — **Figure 9.** **Three ways in.** None of these replaces a laboratory test, and none claims to. What each one gives you is an anchor of your own instead of one from a table.

Two things you may have seen deserve a straight answer. The first is "180 minus your age", the heart rate at the centre of the maximum aerobic function method. It is worth knowing what its own authors say about it: "the 180-Formula does not consider HRmax, and 180 minus age is not a meaningful number other than a means to an ending MAF heart rate."⁷ It is a starting point that then gets adjusted up or down by five or ten beats depending on illness, injury and training history — a rule of thumb offered as a rule of thumb, not an estimate of a physiological boundary.

The second is the state of threshold testing itself, and it cuts both ways. Take one set of blood lactate measurements from eight elite cross-country skiers and analyse it with six accepted methods, and the methods do not agree: the average threshold they returned ranged from 2.39 to 3.52 millimoles per litre, with none of the pairs falling inside the study's own margin.² That is a small sample, and it compares methods rather than testing them against a criterion.

The other side is more encouraging, and it comes from a bigger study. Forty-eight well-trained cyclists each did five graded tests, analysed with eight threshold concepts.³ Every concept turned out to be repeatable — the same rider got much the same answer from test to test, with variation of 3.4 to 8.1 per cent — and the values predicted time-trial performance reasonably well, with correlations from 0.65 to 0.94. So the methods disagree with each other about where the line is, while each one stays consistent with itself and tracks performance.

Which is the practical lesson: pick a method for finding your anchor, and then keep using that one. The number matters much less than the fact that you are comparing like with like over time. Our heart-rate zone calculator shows every number it uses and where it came from, including the maximum, which you can replace with your own.

7 Who was all this built for?

Mostly for people who train a great deal more than most people train (figure 10).

That Norwegian table is headed "intensity scale for elite endurance athletes", and it means it.⁵ The literature on how to spread your training across zones grew up around athletes putting in ten to twenty-five hours a week, as one study of recreational runners describes the field it sits in.⁶ The forty-three runners in that study averaged 3.2 hours a week, with 6.4 years of running behind them.

Two horizontal bars on a scale of training hours per week from 0 to 25. The 43 recreational runners in one study sit at 3.2 plus or minus 0.5 hours a week, with on average 6.4 years of running behind them. The athletes the zone research is about sit at 10 to 25 hours a week. — **Figure 10.** **Two different lives.** Hours as stated in Festa and colleagues.⁶ The gap does not make the zone scales useless at three hours a week. It does mean nobody has established that what works at twenty hours transfers down.

The same paper is blunt about what follows: for recreational athletes "[it] is still unknown what intensity distribution is optimal or if the intensity distribution is or is not critical."⁶ That was written in 2019, and it is a fair summary of where the argument still sits. It is also why the claims about how to use zones belong in a separate piece with the trials laid out rather than in this one.

One more thing that moves underfoot. Your boundaries are not fixed: as you adapt to training they shift, in absolute terms and relative to your maximum, which is why the same authors recommend re-testing rather than setting zones once.¹ A set of zones is a snapshot with a shelf life.

8 So what does this leave you with?

Three things, none of which requires you to change anything you are doing.

Ask which system, before you argue about the zone. Three bands or five, anchored on a maximum or on a threshold. Two people using the word "zone 2" in good faith can be fifty beats apart, and that is a translation problem rather than a disagreement.
Look at the anchor in your watch before you trust the bands. If your maximum heart rate came from a formula, every band on the screen inherits a scatter of seven to eleven beats. Replacing it with a number you produced yourself fixes more than any amount of re-cutting the bands.
Whatever method you pick, keep picking it. Threshold methods disagree with each other by more than you would like, but each one is repeatable enough to track you over time. Consistency beats precision here.

Underneath five coloured bands sit two real boundaries and one number somebody typed in. Knowing which is which is most of what zones can give you.

How we did this (for the curious)

This is an explainer rather than a review, so there is no systematic search behind it. We searched Europe PMC on 8 September 2026 along six lines — training intensity distribution, exercise intensity thresholds and domains, lactate threshold method comparisons, the talk test, age-predicted maximum heart rate, and the maximum aerobic function formula — and picked twelve sources to cover the ground the piece needed. Ten are research (T1) and two are practice (T3). We read all twelve in full at their own address and keep a copy of each.

What the tiers mean here: a T3 source establishes what is being told to athletes and how a method is meant to be applied. It never carries a size of effect and never settles whether something works. Both T3 sources on this page are used for exactly that — the zone tables they publish, and the advice they give about maximum heart rate.

Three things we could not read at source. Iannetta and colleagues (2020) and Jamnick and colleagues (2020) are the primary places where the finding lives that a fixed percentage lands in different intensity domains for different people; neither is open access. We therefore carry that point as MacIntosh and colleagues state it, and attach no number to it. And the Norwegian six-zone table is reproduced as Sun and colleagues print it, not verified against Tønnessen's original.

One number on this page is ours rather than a source's: the three heart-rate bands in figure 5. The percentages come from the three published systems; the maximum of 190 and threshold of 168 are an example we chose; multiplying them is arithmetic. The same goes for the note in figure 8 about a zone edge moving seven beats for every ten in the anchor. Both are labelled as ours in their captions.

What we deliberately left out: whether any particular distribution of training across zones works better than another, whether zone 2 has effects the neighbouring zones do not, and how to test your own lactate at home. The first two are a claim to be checked rather than a scale to be described. The third belongs with a piece on thresholds that we have not written yet.

Sources

Twelve sources, chosen to cover what a zone is, how the models differ, what the bands contain, and how the boundaries are found outside a laboratory. We read every one in full at its own address and keep a copy. T1 is research; T3 is practice — a watch maker and a coaching platform — which tells you what is being recommended and nothing about how well it works. After each entry: what we took from it.

T1 MacIntosh BR, Murias JM, Keir DA, Weir JM. What Is Moderate to Vigorous Exercise Intensity? Frontiers in Physiology. 2021;12:682233. doi:10.3389/fphys.2021.682233 — the two thresholds and the stretches between them; guideline bands of 64–76% and 77–93% of maximum heart rate and 40–59% and 60–84% of heart rate reserve; thirty to fifty minutes at the second threshold and forty to sixty at the highest steady-lactate intensity; the effort-scale anchors of 10.8 ± 1.8 and 13.6 ± 1.8 across 2,560 people (from Scherr et al. 2013); the talk test as an approximation of the first threshold; that boundaries move with training and want re-testing; and that the same percentage of maximum can land two people in different intensity domains.
T1 Carter SL, Newhouse I. Agreement among Six Methods of Predicting the Anaerobic Lactate Threshold in Elite Cross-Country Skiers. International Journal of Exercise Science. 2019;12(2):155–170. doi:10.70252/EZJD8660 — eight male elite skiers, sixteen lactate data sets, six analysis methods; no pair of methods agreed within the study's own margin of ±0.5 mmol/L; mean predicted threshold ranged from 2.39 mmol/L by the Dmax method to 3.52 by the Baldari & Guidetti method.
T1 Heuberger JAAC, Gal P, Stuurman FE, de Muinck Keizer WAS, Mejia Miranda Y, Cohen AF. Repeatability and predictive value of lactate threshold concepts in endurance sports. PLOS ONE. 2018;13(11):e0206846. doi:10.1371/journal.pone.0206846 — forty-eight well-trained male cyclists, five graded tests each, eight threshold concepts; repeatability good to excellent (Cronbach's alpha 0.89–0.96) with within-rider variation of 3.4% to 8.1%; correlations with time-trial performance from 0.65 to 0.94 and with a road race from 0.53 to 0.76.
T1 Heiber M, Schittenhelm A, Schlie J, Beckert M, Graf P, Schmidt A. Garmin Fénix 7® Underestimates Performance at the Lactate Threshold in Comparison to Standardized Blood Lactate Field Test. Open Access Journal of Sports Medicine. 2024;15:37–48. doi:10.2147/OAJSM.S444568 — twenty-six participants (seven women, nineteen men), mean age 25.97; pace at threshold 11.87 km/h by the watch against 13.28 km/h in the field test, 11.96% lower; heart rate at threshold 1.71% lower and not statistically significant.
T1 Sun Q, Yu Y, Cui J, Lin S, Wang X, Zhou T. Recent advances in training intensity distribution theory for cyclic endurance sports: theoretical foundations, model comparisons, and periodization characteristics. Frontiers in Physiology. 2025;16:1657892. doi:10.3389/fphys.2025.1657892 — the three-zone model (below the first threshold, between the two, above the second); the six-zone scale of the Norwegian Olympic Committee with its heart-rate, oxygen-uptake, lactate and effort columns, attributed there to Tønnessen et al. 2024; the eight-zone scale of a national canoe team; and the placement of the first and second lactate thresholds near 2 and 4 mmol/L.
T1 Festa L, Tarperi C, Skroce K, La Torre A, Schena F. Effects of Different Training Intensity Distribution in Recreational Runners. Frontiers in Sports and Active Living. 2019;1:70. doi:10.3389/fspor.2019.00070 — forty-three recreational runners averaging 3.2 ± 0.5 hours a week with 6.4 ± 1.6 years of experience; their description of the distribution literature as concerning athletes training 10–25 hours a week; and their statement that for recreational athletes it remains unknown what distribution is optimal.
T1 Maffetone P, Laursen PB. Maximum Aerobic Function: Clinical Relevance, Physiological Underpinnings, and Practical Application. Frontiers in Physiology. 2020;11:296. doi:10.3389/fphys.2020.00296 — the 180-Formula in full, including the adjustments of minus ten, minus five and plus five beats, and the authors' own statement that 180 minus age "is not a meaningful number other than a means to an ending MAF HR". Used here for what the formula is and how its authors describe it, not for whether it works.
T1 Orizola-Cáceres I, Cerda-Kohler H, Burgos-Jara C, Meneses-Valdes R, Gutierrez-Pino R, Sepúlveda C. Modified Talk Test: a Randomized Cross-over Trial Investigating the Comparative Utility of Two "Talk Tests" for Determining Aerobic Training Zones in Overweight and Obese Patients. Sports Medicine – Open. 2021;7:24. doi:10.1186/s40798-021-00315-9 — nineteen participants, mean age 34.9, mean body mass index 31.8; power at a talk rating of 2–3 equivalent to power at the first ventilatory threshold (mean difference −1.3 W), and at 6–7 to the second (mean difference 11.1 W).
T1 Tanaka H, Monahan KD, Seals DR. 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 — a meta-analysis of 351 studies covering 492 groups and 18,712 people giving 208 − 0.7 × age, cross-validated in a laboratory study of 514 people giving 209 − 0.7 × age; "standard deviations ranging from 7 to 11 beats/min" around the line; no difference between men and women; sedentary 212 − 0.7 × age against endurance-trained 205 − 0.6 × age; and roughly ten beats between the two formulas by age seventy.
T1 Robergs RA, Landwehr R. The surprising history of the "HRmax=220-age" equation. Journal of Exercise Physiology online. 2002;5(2):1–10 — the origin of 220 − age in Fox et al. 1971: about thirty-five data points drawn from roughly eleven references, with no regression performed, and the authors' own note that no single line adequately represents the data.
T3 Polar. Running Heart Rate Zones: The Basics. polar.com/blog/running-heart-rate-zones-basics, read 8 September 2026 — the five-zone model as most watches ship it, cut at 50–60%, 60–70%, 70–80%, 80–90% and 90–100% of maximum heart rate, with zone 2 described as "light"; and the recommendation that the "most simple way" to find your maximum is "the rule 220-your age".
T3 TrainingPeaks / Friel J. Joe Friel's Quick Guide to Setting Zones. trainingpeaks.com/learn/articles/joe-friel-s-quick-guide-to-setting-zones, read 8 September 2026 — the definition of a zone system as a parameter expressed as a percentage of a threshold; the seven running zones on threshold heart rate (below 85%, 85–89%, 90–94%, 95–99%, 100–102%, 103–106%, above 106%); the six power zones from Allen and Coggan on functional threshold power (below 55%, 55–74%, 75–89%, 90–104%, 105–120%, above 120%); the thirty-minute time trial as a threshold test; and the instruction not to use 220 minus age.

Found a mistake here? Tell us at info@enduranceproof.com — you do not need to be a scientist, and "this number looks off" is a perfectly good message. Anything we correct, and when, goes on our corrections page.

This is educational material about how training zones are defined and measured, not training or medical advice, and not a recommendation for or against any method, device or platform. Nothing here is a recommendation about what any individual should do.

Training zones, from scratch