Training guide
Zone 2 is steady, comfortable cardio at a pace you could keep up for a long time while still talking in full sentences. It has become the most talked-about way to train, with big claims about fat burning and mitochondria, yet the zone systems behind it don't even agree on the heart rate: for the same person, a common watch default and Norway's Olympic scale put zone 2 about 20 beats apart.
The honest headline: steady cardio works, and it's the easiest way to build up your weekly minutes, but it isn't a special switch. Harder training builds mitochondria and fitness at least as well per minute, and fat loss depends on the total energy you use, not the zone.
This guide shows how to find your own zone 2 with the talk test, why heart rate formulas are only a rough start, what the trials say about zone 2 against harder training, and how it fits the 150 to 300 minutes a week that health guidelines ask for, with steady cardio moves, workouts and plans to follow.
A common watch default (Garmin's, for example) puts zone 2 at 60 to 70% of your maximum heart rate. Norway's Olympic scale puts it at about 72 to 82%, and a 2025 expert panel defined it as the effort just below your first threshold, where your breathing first starts to deepen. A cyclist's zone 2 heart rate may be a runner's zone 1.
If you can still talk comfortably in full sentences, you're at or just below your first threshold, which is where the experts put the top of zone 2. The NHS test for moderate activity, that you can talk but not sing, sits at or a little above that point (our reading).
208 minus 0.7 times your age fits large data sets better than 220 minus age, but any age formula misses individuals by about 11 beats a minute on average, and by 20 or more for some. The first threshold also falls anywhere from about 60% to 90% of maximum heart rate from one person to the next.
Across 353 training studies, mitochondria, the energy factories in muscle, grew by roughly similar amounts with steady moderate training and with intervals, and the harder training did it faster per hour. For fat loss, interval and steady training lose about the same fat when the work is matched.
For health, the target is 150 to 300 minutes of moderate activity a week, or 75 to 150 minutes of vigorous activity, or a mix. Steady cardio is the easiest way to build up those minutes, and adding some harder work raises fitness a little more.
As effort rises, your body passes two turning points. At the first threshold, lactate in the blood starts to rise above its resting level and your breathing deepens. At the second, lactate climbs steeply and the effort can't be held for long. Scientists find these with blood lactate or breathing-gas tests, and they have counted 25 different ways of defining a lactate threshold, so even "threshold" isn't one number.
Zone systems carve this range up differently:
Take a 40-year-old with an estimated maximum heart rate of 180 beats a minute. The watch default puts their zone 2 at 108 to 126 beats a minute; Olympiatoppen's scale puts it at 130 to 148. The two ranges don't even overlap (our arithmetic from the published percentages). In a survey of 778 coaches, athletes and scientists, the start of zone 2 averaged 66% of maximum heart rate for cyclists and 70% for runners, and the authors note that the current debate about zone 2 grew mostly out of road cycling.
Below the first threshold, lactate stays close to its resting level, breathing stays steady, and trained athletes can keep going for hours. Above it, lactate rises because you break down carbohydrate faster as effort climbs, not because your muscles run short of oxygen.
Fat burning peaks at moderate effort: at about 64% of VO2 max (the most oxygen your body can use in all-out exercise) in trained cyclists, and it becomes negligible near 90%. On average, the fat-burning peak sits about 11 beats a minute below the first threshold.
Your own thresholds, and so your zone 2, shift with:
In studies, the point where speech first became less comfortable matched the first ventilatory threshold (the first breathing threshold) on treadmills and bikes. It kept tracking the threshold after training moved it, set the pace of 30-minute runs on its own, and matched the first threshold in heart patients (10 studies, 414 people). Its limits: the studies are small, and people tended to drift slightly above the threshold.
Settle into a steady pace for at least 5 minutes (our suggestion, because breathing takes a couple of minutes to catch up with a change of pace), then say a couple of sentences out loud:
Athletes' zone 2 is "fairly light": about 2 or 3 out of 10 on Norway's Olympic scale. Health guidance describes moderate activity as 5 or 6 out of 10, so a guideline "moderate" walk or ride can reach into the zone above an athlete's zone 2. For health, both count towards your weekly minutes, and for a beginner a brisk walk can be both (our reading).
Estimate your maximum heart rate as 208 minus 0.7 times your age, which fits large data sets better than the old 220 minus age. If you have a measured maximum, use that instead, and update it as you get older.
Treat every number as plus or minus about 11 beats: that's the typical error of any age formula, and for some people it's more than 20. Because the first threshold sits anywhere from about 60% to 90% of maximum from one person to the next, use the list to start and let the talk test overrule it. On a beta blocker, skip heart rate targets: the medicine slows the heart, so go by the talk test.
Our arithmetic, in beats a minute, for the watch default (60 to 70%) and Olympiatoppen's zone 2 (72 to 82%):
Wrist sensors are close to a chest strap or ECG (heart trace) when walking and running, about half a beat low on average, but less accurate when cycling (about 5 beats low) and in weight training (about 7 low), and accuracy varies by device. A chest strap is the better choice on a bike.
About 100 steps a minute is a moderate walking pace for most adults aged 21 to 85, and about 130 is vigorous up to age 60. These numbers don't adjust for fitness, so a fit person may need to walk faster, walk uphill or jog to reach moderate effort. To check, count your steps for 15 seconds and multiply by 4 (our suggestion).
A lactate or breathing-gas test finds your own thresholds, and it's the only way to set zones precisely. In 50 trained cyclists tested this way, the different markers used to define zone 2 varied by 6 to 29% from rider to rider. A test is useful for athletes; for health, you don't need one (our view).
In a review of 353 training studies with 5,973 people, mitochondrial content in muscle rose by roughly similar amounts with steady moderate training (about 23%), high-intensity interval training, or HIIT (about 27%), and sprint intervals (about 27%). Per hour of exercise, sprint intervals were roughly 3.9 times and HIIT roughly 1.7 times as efficient as steady training. These are approximate figures. More sessions a week, and starting less fit, meant bigger gains.
A 2025 review concluded that the evidence does not support zone 2 as the best intensity for mitochondria or fat-burning capacity, and that harder work matters more when training time is short. With the work matched in the same people, one leg each, intervals raised mitochondrial content more than steady cycling (10 men, 2 weeks). Steady moderate training does build mitochondria; it just isn't uniquely good at it, and how much volume and intensity each contribute is still debated.
Easy exercise burns a larger share of fat while you're doing it. In trained men, fat burning peaked at about half a gram a minute, roughly 30 g of fat an hour at best (our approximate arithmetic). But fat loss depends on the total energy you use over weeks: in a high-certainty review of randomised trials, interval and steady training lost about the same fat when the work was matched. Interval training also raised fat burning during exercise at least as much as steady training did.
Across 19 trials with 644 people with overweight or obesity, training at the fat-burning peak reduced weight and fat compared with no exercise, but certainty was very low to moderate, and it wasn't compared with other intensities. The idea that zone 2 is needed for "metabolic flexibility" comes mainly from comparing professional cyclists with less fit people at one point in time, not from training trials.
VO2 max is measured in millilitres of oxygen per kilogram of body weight per minute (mL/kg/min). In 28 controlled trials of 723 healthy adults aged 18 to 45, steady endurance training raised it by about 4.9 mL/kg/min against no exercise, and HIIT by about 5.5. In the trials that compared the two directly, HIIT gave about 1.2 mL/kg/min more. The gap was bigger with longer intervals and longer programmes, and in people with heart and metabolic conditions (about 3 mL/kg/min). In the 353-study review, total training load and the number of sessions a week drove the gains most.
In the Generation 100 trial, 1,567 people aged 70 to 77 did 5 years of supervised training twice a week, steady or intervals, or followed the national activity guidelines. Death rates didn't differ significantly; the interval group showed a trend towards fewer deaths that could have been chance.
In US studies of 116,221 adults followed for 30 years, moderate and vigorous activity were both linked with lower death rates, with the benefit close to its largest at 150 to 300 minutes of vigorous or 300 to 600 minutes of moderate activity a week. In another large study, as little as 15 to 20 minutes of vigorous activity a week was linked with lower death rates. These are observational links.
Elite endurance athletes training 10 to 13 times a week do about 75 to 80% of their sessions at low intensity and 15 to 20% hard, with little at threshold. Most follow a "pyramidal" pattern (mostly easy, some threshold work, a little very hard), and some switch to "polarised" training (easy and hard, little in between) as competitions near.
Unsettled. A 2024 analysis of 17 studies found a small fitness edge for polarised training, but only in studies under 12 weeks and in highly trained athletes, and no difference in time trials. A 2025 analysis of individual data from 13 studies found no difference between polarised and pyramidal training, though competitive athletes may suit polarised training and recreational athletes pyramidal. A 2026 analysis found no clear winner. One 9-week trial of 48 well-trained athletes favoured polarised training, but in other small trials recreational runners improved on both patterns, and well-trained runners improved on all four patterns tested.
In a trial of 78 adults, 69% of those doing one 60-minute session a week showed no fitness gain after 6 weeks, against none of those doing four or five. Two extra sessions a week then brought everyone along. People vary a lot in how much they gain, partly because of their genes, but more training helps nearly everyone.
No guideline sets a dose for zone 2 as such. These are the adult activity guidelines, with our starting points labelled.
The World Health Organization (WHO): 150 to 300 minutes of moderate activity a week, or 75 to 150 minutes of vigorous activity, or a mix, plus muscle strengthening on 2 or more days. More than 300 minutes may bring further benefit. The NHS suggests spreading it over 4 to 5 days, or every day, and the UK Chief Medical Officers say bouts of any length count.
The American College of Sports Medicine advises 30 minutes or more of moderate activity on 5 or more days a week, and the 2024 European blood pressure guideline 30 minutes or more on 5 to 7 days. Our editorial starting point: 3 to 5 sessions a week of 20 to 30 minutes at a full-sentences pace, adding about 5 minutes a session each week until you reach 30 to 60 minutes.
If you'd like to run your zone 2, start with walk-run intervals. The NHS Couch to 5K plan begins with 1-minute runs and 90-second walks, 3 times a week, building to 30 minutes of running over 9 weeks or longer. Build distance gradually: in one exploratory study, new runners who raised their weekly distance by more than 30% had more overuse injuries than those who raised it by under 10%, though a strict graded plan didn't prevent injuries in a trial of 532 new runners.
Our editorial example: three steady 40-minute sessions at a full-sentences pace, one interval session such as four 4-minute hard efforts, and two strength sessions. That's 120 moderate minutes plus 16 hard ones, which count roughly double (the NHS says 75 vigorous minutes can give similar benefits to 150 moderate), so about 150 in all before warm-ups. The 7-day plan below is built the same way, with three strength days.
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WHO and the NHS ask for muscle strengthening on 2 or more days a week as well as aerobic activity. In pooled trials, strength training cut sports injuries to under a third, while stretching didn't reduce them. Calf raises, step-ups, lunges and bridges suit walkers and runners (our suggestion).
For steady cardio, the first 5 minutes at an easy pace are your warm-up, and a few easy minutes at the end are your cool-down; stretches afterwards are optional, for comfort, as in our plans. Our warm-up guide has the evidence.
Any of these is zone 2 if you can still talk in full sentences: start with 20 to 30 minutes on 3 to 5 days a week (our editorial starting point), and use the step jack, march and punches at home for no impact.
3D demoTreadmill walkingBeginner · Cardio machine
3D demoStationary cyclingBeginner · Cardio machine
3D demoIndoor Rowing (Rowing Machine)Beginner · Cardio machine
3D demoElliptical trainerBeginner · Cardio machine
3D demoTreadmill joggingIntermediate · Cardio machine
3D demoStep jack (low-impact jumping jack)Beginner · No equipment
3D demoStanding marchBeginner · No equipment
3D demoStanding punches (shadow boxing)Beginner · No equipmentDo the strength moves on 2 days a week, 2 to 3 sets of 8 to 15 each (our editorial starting point), and the two stretches after cardio, 30 seconds each side, for comfort.
The easy cardio workout is a zone 2 session. The low-impact workout and the walk after meals are gentler ways to add minutes, and the interval sessions are there if you want one harder day a week.
A steady 30 to 45 minute cardio session at talk-but-not-sing pace: walk, cycle, row or cross-train, counting toward weekly activity guidelines.
40 minBeginner3 movesCardio machine, A wallA 25-minute standing cardio circuit with no jumping: marching, step jacks, sit-to-stands, punches, step-ups and wall push-ups, with a seated option for most moves.
25 minBeginner9 movesA bench or box, A stepA 10-minute routine for straight after a meal: an easy walk, a few simple standing moves from blood sugar trials, then a short walk to finish.
10 minBeginner6 movesCardio machine, A bench or boxA 25-minute walk with short faster bouts: notice your heart and breathing speed up, then settle. A gentle way to get used to the feelings of effort.
25 minBeginner5 movesCardio machine, A wallA 25-minute interval session on a bike or rower: one-minute hard efforts with two minutes easy, building from 4 to 8 rounds.
25 minIntermediate1 movesCardio machineAn 8-minute dynamic warm-up for runners: ankle and hip mobility, lunges, skips and pogo hops.
8 minIntermediate8 movesA wallSeven stretches for after a run: calves, soleus, quads, hip flexors, hamstrings and glutes.
10 minBeginner7 movesA wallThe 7-day plan has two cardio days and two walks, about 150 minutes a week; the beginner plan starts with 15 to 20-minute walks; the plan for women over 50 has two 30 to 45-minute walks or rides; and the plan for men over 40 pairs an easy cardio day with an interval day.
A full week that mixes intensities: three strength days, two cardio days, a mobility day and an easy day, never seven hard days.
3 training days45 minBeginner2 days a weekYour first four weeks: two, then three short strength sessions a week at home plus walks, building gently to a full routine.
2 training days20 minBeginner3 days a weekA weekly plan for women over 50: strength, bone-loading and balance on 3 days plus walking, built on UK osteoporosis consensus advice.
3 training days45 minBeginner3 days a weekA 3-day strength plan for men over 40 with power and bone work, two cardio days and mobility, built on research on ageing muscle.
3 training days45 minBeginnerEasy, steady cardio is safe for most people, and WHO says medical clearance is generally unnecessary before light or moderate activity. The NHS advises speaking to your GP first if you haven't exercised for some time, or have a medical condition or concerns. Our HIIT guide covers who should check first before harder training.
Stop and call 999 (don't drive yourself to A&E) for:
Get advice the same day for:
That's a common watch default (Garmin's, for example). Norway's Olympic scale puts zone 2 at about 72 to 82%, experts define it by your own first threshold, and that threshold sits anywhere from about 60% to 90% of maximum heart rate in different people.
It underestimates maximum heart rate in older adults; 208 minus 0.7 times your age fits better. And every age formula misses individuals by about 11 beats on average, and by more than 20 for some.
Mitochondria grew by roughly similar amounts with moderate, interval and sprint training, and faster per hour with the harder kinds. A 2025 review found no support for zone 2 as the best intensity.
Easy exercise burns a larger share of fat while you do it, but fat loss depends on total energy: interval and steady training lose the same fat when the work is matched (high-certainty evidence). Interval training improves fat burning during exercise at least as much as steady training.
Lactate rises because you break down carbohydrate faster as effort climbs, not because your muscles are short of oxygen. Physiologists have argued about the "anaerobic threshold" for more than 50 years, and the shortage-of-oxygen explanation hasn't held up.
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For health, anything from moderate to vigorous counts towards your weekly minutes. The case against the "grey zone" comes from athletes training 10 or more times a week, and even there it's mixed: recreational runners improved on both patterns, and the largest analysis found no difference between polarised and pyramidal training.
Elite athletes train 10 to 13 times a week. When your total time is short, harder work matters more, and the guidelines allow moderate, vigorous or a mix. Mostly easy with one or two harder sessions suits many people (our suggestion), but there's no magic ratio.
The talk test matches the first threshold closely enough to set and control your pace.
The "180 minus your age" heart rate of the maximum aerobic function (MAF) method hasn't been tested properly: its own authors write that its links with lab measures, health and performance "must be verified scientifically".
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Zone 2 is steady, comfortable exercise at a pace you could keep up for a long time while still talking in full sentences. The name comes from heart rate zone systems, which don't agree on the numbers: a common watch default (Garmin's, for example) calls 60 to 70% of your maximum heart rate zone 2, while Norway's Olympic scale uses about 72 to 82%. Experts now define it as the effort just below your first threshold, where your breathing first starts to deepen.
As a rough start, estimate your maximum as 208 minus 0.7 times your age: for a 40-year-old that's about 180, so 60 to 70% is 108 to 126 beats a minute and 72 to 82% is 130 to 148. Age formulas can be out by 11 beats or more, and the first threshold sits anywhere from about 60% to 90% of maximum in different people, so check with the talk test. On a beta blocker, heart rate targets don't apply.
Use the talk test. After at least 5 minutes at a steady pace, say a couple of sentences: if you can speak comfortably in full sentences, you're in zone 2 or easier; if talking has just started to feel harder, you're at the top of it; if you're down to short sentences, slow down. In studies, the point where speech first gets harder matched the first breathing threshold on treadmills and bikes.
For many people, yes: brisk walking counts as moderate activity, and about 100 steps a minute is a moderate pace for most adults. Fitter people may need to walk uphill, walk faster or jog to reach the same effort, so go by the talk test rather than the activity.
No. Easy exercise burns a larger share of fat while you do it, but fat loss depends on the total energy you use, and interval and steady training lose the same fat when the work is matched. Zone 2's real advantage is that it's easy to do a lot of it.
Not more than other kinds of cardio. Across 353 studies, mitochondria in muscle increased by roughly similar amounts with steady moderate training, high-intensity intervals and sprint intervals, and the harder kinds did it faster per hour. A 2025 review concluded the evidence doesn't support zone 2 as the best intensity for this.
Guidelines ask for 150 to 300 minutes of moderate activity a week, spread over 4 or 5 days or more, and bouts of any length count. A practical start is 3 to 5 sessions of 20 to 30 minutes, adding about 5 minutes a session each week until you reach 30 to 60 minutes (our suggestion).
Not for health: anything from moderate to vigorous counts towards your weekly minutes, and vigorous minutes count roughly double. The advice to avoid the "grey zone" comes from athletes who train 10 or more times a week, and even there the evidence is mixed.
Both improve fitness. HIIT raises VO2 max a little more (about 1.2 mL/kg/min in healthy adults) and saves time, while steady cardio is easier to do in larger amounts; for fat loss they're equal when the work is matched. Most people do well with mostly easy sessions and one or two harder ones (our suggestion).
Watches usually set zones as percentages of an estimated maximum heart rate, and that estimate can be out by 11 beats or more. If your true maximum is higher than the watch thinks, every zone reads too high. Enter a measured maximum if you have one, or trust the talk test.
It describes how many elite endurance athletes train: about 80% of sessions easy and 20% hard, with little in between. Trials comparing it with "pyramidal" training (mostly easy, some threshold work, a little very hard) found no clear winner overall, though competitive athletes may do slightly better with it. For health, any mix that reaches the weekly minutes works.
Fitness improves within weeks. In one trial, everyone doing four or five 60-minute sessions a week improved within 6 weeks, while most people doing one session a week didn't, so how much you do matters.
Exercise education, not a personal prescription, and clinical review of these guides is pending. Check with a GP before starting hard training if you have a heart condition, chest pain, dizziness or breathlessness when active, and stop for sharp or increasing pain. Health disclaimer.
