Training zones, from scratch

0:03 · Five zones, and five more that disagree

Your watch has five heart-rate zones, and so does your training plan. And when both of them say "zone two", they can mean heart rates fifty beats apart.

0:16 · What a zone actually is

Underneath every zone model sit two real boundaries. Both readings are being used correctly. It is what happens when two people paint their own lines on the same road. This is EnduranceProof. By the end you will know where your two boundaries are, and how to find them without a laboratory. This video is about where those lines are. What training between them does is the next one. Start with what a zone actually is.

0:57 · The recipe: three choices

A zone system makes three choices, and that is the whole recipe. Something you can measure — heart rate, power, pace, or how hard it feels. One number to measure it against — your maximum, the room between resting and maximum, or the point where it starts to get hard. That one gets a name in a moment. And how many bands you cut the range into. Change any one of those three and the same run lands in a different zone. That is all "zone two" ever was: a band somebody drew on a scale.

1:35 · Two real boundaries, not five zones

Your body does not have five zones. It has two points where something measurable changes. At the first one, lactate in your blood starts climbing above its resting level, and your breathing steps up out of proportion to the oxygen you are using. That change is the first threshold. Higher up there is a second point where the disturbance stops being gradual and starts accelerating. Those two points cut the range into three stretches, and what separates them is time. Below the first, you could keep going for hours. Between the two, you are still paying for it aerobically, but the bill grows as you climb. Right at the second threshold, trained athletes typically last thirty to fifty minutes. Above that second boundary you have minutes, not hours. That second point is the one your watch and your plan call your threshold.

2:40 · Three, five, six, seven, eight — all in use

So why do the numbers disagree? Because the number of bands is a choice, and so is the anchor. Research usually works in three zones. Most watches ship five, and the Norwegian Olympic Committee uses six for its endurance athletes. Joe Friel's running zones run to seven, cut as shares of your threshold heart rate rather than your maximum. One national team uses eight, and none of them is wrong. But the outlined band in each row is the one that system calls zone two, and they are not the same band. Put one runner through three of them, in a worked example of ours. Give her a maximum of one ninety and a threshold of one sixty-eight, and the three zone twos land fifty beats apart. That arithmetic is ours. The percentages are exactly as the three systems publish them. It is a translation problem, not a disagreement.

3:48 · Inside the bands: one real scale

It helps to look at one real scale instead of describing them. The Norwegian six-zone scale lines up four different measures for every band. A share of maximum heart rate, and a share of maximum oxygen uptake. A blood lactate range, and a point on the six to twenty effort scale. On that scale, easy sits under one and a half millimoles per litre, and the hardest row is above ten. Reading across a row shows you what a zone boundary is actually made of. Two things in that table stand out. In this scale the boundary between easy and moderate sits at around two and a half millimoles of lactate per litre. The boundary between moderate and hard sits at around four. That is roughly where the two thresholds usually sit. The six bands are those three stretches, subdivided. And a caveat belongs right beside the table. It is a scale for elite endurance athletes, and it says so.

5:01 · What each band is aimed at

A scale shows what a band contains. What it is for is a separate layer, and that one is written by whoever drew the lines. Here is a five-zone watch model in its own words. Zone one is for recovery, zone two for endurance. Zone three the maker itself calls a grey area. Zone four is the basis of threshold training, and zone five is speed and power. But a purpose travels with its own system. Joe Friel's zone two sits at eighty-five to eighty-nine per cent of your threshold heart rate, and it is a working band. This zone two sits at sixty to seventy per cent of your maximum, and it is a gentle one. Whether an adaptation belongs to a band, or simply to the effort and the hours, is a different question. That is the zone two question, and it is the next video.

6:08 · Where your watch got its anchor

That is what a zone is. Now the part that decides whether the numbers on your wrist mean anything.

6:21 · The watch against a field test

Twenty-six runners did the threshold test built into a sports watch, and then a graded blood-lactate field test. The heart rate the watch put on the threshold was close, one and seven-tenths per cent lower, too small to show up in the statistics. The pace it put there was nearly twelve per cent slow. That is one watch model in one study, so read it as how these estimates behave rather than as a number for your device. The quieter reason sits in your settings screen. Most watches build their bands from your maximum heart rate, and most of them do not know it. They estimate it from your age. The best-supported line is two hundred and eight minus zero point seven times your age. The laboratory arm of that same study put it at two hundred and nine minus zero point seven. Around that line, individual maxima scattered with standard deviations of seven to eleven beats. Every band on the screen inherits that scatter.

7:35 · Three ways to find your own

So how do you find your own, without a lab? Three routes are in common use, and each one aims at a boundary rather than at a zone. Friel's method is thirty minutes hard and alone, with the average heart rate over the last twenty taken as an estimate of your threshold. It is a practitioner's method rather than a validated protocol — but it anchors on something you produced. The talk test rests on where speech starts to break up, which tracks the first threshold. In one trial, nineteen people on a bike rated how comfortably they could talk on a one-to-ten scale. The power at a rating of two to three matched the power at the first threshold to within about a watt. Those nineteen had a body mass index around thirty-two and were not athletes. So it tells you the method has a physiological basis, not how well it works on a fit runner. And how hard it feels was measured too. Across two and a half thousand people, the average rating on the six-to-twenty scale was ten point eight at the boundary between moderate and vigorous. The spread is the interesting part. A standard deviation of one point eight means a rating of twelve sits comfortably inside it. None of these replaces a laboratory test. What each one gives you is an anchor of your own instead of one from a table. That leaves one catch worth knowing, and it cuts both ways. Take the blood lactate measurements of eight elite skiers and analyse them with six accepted methods. The six do not agree with each other. The thresholds they return range from two point three nine to three point five two millimoles per litre. Then take a bigger study of forty-eight well-trained cyclists, with five graded tests each, and every method turns out repeatable. The same rider gets much the same answer from test to test, within three point four to eight point one per cent. So the methods disagree with each other about where your line is, while each one stays consistent with itself. Which is exactly why the sensible thing is to pick one and keep picking it.

10:09 · Who the research was built for

One thing worth knowing before you take any of this to heart. That Norwegian table is headed "intensity scale for elite endurance athletes", and it means it. The research on spreading your training across zones grew up around people training ten to twenty-five hours a week. The forty-three recreational runners in one study averaged three point two hours. That does not make the scales useless at three hours a week. It does mean nobody has shown that what works at twenty hours transfers down.

10:45 · What this leaves you with

So, three things, and none of them asks you to change your training. Ask which system before you argue about the zone. Two people using zone two in good faith can be fifty beats apart. Look at the anchor in your watch before you trust the bands. If your maximum came from a formula, every band inherits its scatter. And whatever method you pick, keep picking it. 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. The whole piece, with all twelve sources and every figure, is at enduranceproof dot com. Our next video takes the zone two claim itself apart. And if you would like that one when it lands, subscribing is how you get it.