"Zone 2" comes from the heart-rate zones that endurance coaches use to split easy work from hard work. It has become the name for steady, moderate cardio: a pace you could hold for a long time, hard enough to raise your breathing, easy enough to keep a conversation going.
This page covers what zone 2 actually means in the research, why the numbers you'll see disagree, how to find yours without a lab, how much fits beside a lifting week, examples on each machine, and what it does and doesn't do. It's about training, not the scale. Whether to do cardio before or after lifting, and how much it costs your lifting, is on cardio and lifting.
What zone 2 is
There's no single definition. A 2025 commentary from 14 sport scientists and coaches set out to agree one, and their consensus was that zone 2 sits immediately below the first lactate or ventilatory threshold.1 That threshold is the intensity above which blood lactate rises noticeably above resting values and your breathing climbs faster than your oxygen use. Below it, moderate exercise could be kept up for hours.2
Outside a lab, the same idea gets written in several ways:
| Method | Zone 2, or the moderate band it sits in |
|---|---|
| Blood lactate | 1.5 to 2.5 mmol/L, in one national Olympic federation's zone scheme3 |
| Percent of max heart rate | 72% to 82% in that scheme;3 the standard "moderate" band is 64% to 76%2 |
| Percent of heart rate reserve | Moderate is 40% to 59% of reserve (max minus resting heart rate)2 |
| The talk test | Talking is still comfortable; the point where it turns uncertain reflects the first threshold4 |
| Effort out of 10 | Moderate is usually a 5 or 65 |
The 2021 paper on what "moderate" means puts the two ideas together: the upper limit of moderate intensity is marked by the first threshold.2 So zone 2 is the top end of moderate.
Why the numbers disagree
Because people differ more than the percentages do. In 50 cyclists, 30 men and 20 women, tested in a lab, fixed percentages of max heart rate and fixed lactate values showed wide individual differences as markers of zone 2.3 In 863 exercise tests, the first threshold sat at about 55% of heart rate reserve on average, but individuals ranged from about 26% to 86% of their aerobic reserve.6 The effort rating at that threshold barely moved: about 12 or 13 on the 6-to-20 scale, for sedentary people and endurance athletes alike.6
That's why a heart-rate formula is a starting point, and your breathing is the check. The 2021 paper makes the same point: prescribing by a fixed percentage of max heart rate doesn't account for how much these boundaries vary between people.2
How to find your zone 2 without a lab
- Estimate your max heart rate: 208 minus 0.7 times your age. That equation came from a meta-analysis of 351 studies and 18,712 people, and a lab study of 514 healthy adults gave almost the same line; the familiar 220 minus age underestimates max heart rate in older adults.7
- Turn it into a range. Either method in the table above works as a first guess, and the heart rate zone calculator does the arithmetic.
- Check it with the talk test. Say a sentence or two out loud. If that's comfortable, you're below the threshold; if you're not sure you could keep talking, you're at it, so ease off a little. In 16 physically active volunteers, holding the "still comfortable to talk" stage for a 30-minute run produced an intensity suited to training in healthy adults and to long sessions in athletes.8
- Recheck every month or two. As you get fitter, the boundaries move, which is why the 2021 paper says they need reassessing.2
A worked example, for a 30-year-old with a resting heart rate of 60:
| Method | Calculation | Range |
|---|---|---|
| Estimated max | 208 − (0.7 × 30) | 187 beats a minute |
| 64% to 76% of max | 0.64 × 187 to 0.76 × 187 | 120 to 142 |
| 40% to 59% of reserve | 60 + 0.40 × 127 to 60 + 0.59 × 127 | 111 to 135 |
| 72% to 82% of max | 0.72 × 187 to 0.82 × 187 | 135 to 153 |
The three ranges overlap at about 135 beats a minute, and they still disagree by more than 20 beats at the edges. Start in the overlap and let the talk test decide.
No heart-rate monitor? Use effort. The WHO describes moderate activity as usually a 5 or 6 on a 0-to-10 scale,5 and in the 863 tests above, the threshold came at about 12 or 13 on the 6-to-20 scale, between the scale's "light" at 11 and "somewhat hard" at 13.6 If it feels like more than somewhat hard, slow down.
How much a week beside lifting
The World Health Organization's guideline for adults is 150 to 300 minutes of moderate-intensity aerobic activity a week, or 75 to 150 minutes of vigorous activity, plus muscle-strengthening activities on two or more days.5 Zone 2 counts toward the moderate minutes.
- Three sessions of 50 minutes, on the days you don't lift, reaches 150.
- Five of 30, some after lifting, gets there too.
- Less than that still counts. The WHO's guidelines say some physical activity is better than none.5
- Starting from zero? Two sessions of 20 to 30 minutes is a fair first week. Add about ten minutes a session every week or two until you reach the total you want.
If your lifting is the priority, place the cardio so it doesn't leave you tired for the next session; cardio and lifting covers the order, the timing and how big the interference effect is, and rest days covers easy cardio on the days off.
Zone 2 examples, machine by machine
| Option | How to keep it in zone 2 |
|---|---|
| Stationary bike | A steady cadence against resistance you could hold for an hour |
| Treadmill, incline walk | Raise the grade before the speed, until talking takes a little effort |
| Rowing machine | Long, easy strokes at a steady rate; ease off when talking gets hard |
| Elliptical or stair climber | A slow, even pace; hands off the rails if you can stay steady |
| Easy run | Slow enough to talk; walk breaks when you can't |
| Walking outdoors | Brisk, with hills if a flat walk feels effortless |
The rowing machine is cardio; the seated cable row is the lifting exercise with a similar name. The expert panel's sessions don't have to be one steady block, either: continuous, variable or interval-style sessions just under the threshold all fit their definition.1
What zone 2 does and doesn't do
- It trains your aerobic system, but not uniquely. The expert panel expected a broad range of adaptations from zone 2, and added that they might not be unique to it: sessions slightly harder or easier could produce them too.1
- It isn't a magic intensity. A 2025 review concluded that current evidence doesn't support zone 2 as the optimal intensity for improving the muscles' mitochondrial capacity, and pointed to substantial evidence for harder exercise.9 The review notes that much of the enthusiasm comes from elite endurance athletes, who do large volumes of zone 2 training.9
- It's one way to fill the minutes, not the only one. A week can hold mostly steady sessions with a harder one now and then; cardio and lifting covers how either kind sits beside your lifting.
If you'd rather have the week planned
Fitting lifting, cardio and the rest of your life into one week is a scheduling problem as much as a training one. Coaching is the version where your workouts are built around the days you actually have, and a weekly call looks at the week you just had and rebuilds the next one around what's coming. Coaching for a week that doesn't hold still explains how that works, and apply is the first step. Otherwise: work out your range, then do 30 minutes on a bike this week, talking-pace.
General education only, not medical advice. If you have a medical condition, are pregnant, or take medication, check with your doctor before changing how you train or eat.
Sources
- Sitko S, Artetxe X, Bonnevie-Svendsen M, et al. What is "zone 2 training"?: experts' viewpoint on definition, training methods, and expected adaptations. International Journal of Sports Physiology and Performance, 2025. https://pubmed.ncbi.nlm.nih.gov/40010355/ (accessed October 24, 2026).
- MacIntosh BR, Murias JM, Keir DA, et al. What is moderate to vigorous exercise intensity? Frontiers in Physiology, 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC8493117/ (accessed October 24, 2026).
- Meixner B, Filipas L, Holmberg HC, et al. Zone 2 intensity: a critical comparison of individual variability in different submaximal exercise intensity boundaries. Translational Sports Medicine, 2025. https://pmc.ncbi.nlm.nih.gov/articles/PMC11986187/ (accessed October 24, 2026).
- Bok D, Rakovac M, Foster C. An examination and critique of subjective methods to determine exercise intensity: the talk test, feeling scale, and rating of perceived exertion. Sports Medicine, 2022. https://pubmed.ncbi.nlm.nih.gov/35507232/ (accessed October 24, 2026).
- Bull FC, Al-Ansari SS, Biddle S, et al. World Health Organization 2020 guidelines on physical activity and sedentary behaviour. British Journal of Sports Medicine, 2020. https://pmc.ncbi.nlm.nih.gov/articles/PMC7719906/ (accessed October 11, 2026).
- Gaskill SE, Skinner JS, Quindry J. Ventilatory threshold related to V̇O2 reserve, heart rate reserve, and rating of perceived exertion in a large varied sample. Medicine & Science in Sports & Exercise, 2023. https://pmc.ncbi.nlm.nih.gov/articles/PMC10524184/ (accessed October 24, 2026).
- Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology, 2001. https://pubmed.ncbi.nlm.nih.gov/11153730/ (accessed October 24, 2026).
- Woltmann ML, Foster C, Porcari JP, et al. Evidence that the talk test can be used to regulate exercise intensity. Journal of Strength and Conditioning Research, 2015. https://pubmed.ncbi.nlm.nih.gov/25536539/ (accessed October 24, 2026).
- Storoschuk KL, Moran-MacDonald A, Gibala MJ, et al. Much ado about zone 2: a narrative review assessing the efficacy of zone 2 training for improving mitochondrial capacity and cardiorespiratory fitness in the general population. Sports Medicine, 2025. https://pubmed.ncbi.nlm.nih.gov/40560504/ (accessed October 24, 2026).