Zone 2 cardio is steady, low-intensity aerobic exercise, such as brisk walking, easy cycling or a gentle jog, done at a pace where you can still hold a conversation. On many fitness watches, Zone 2 means 60 to 70% of your maximum heart rate. In the lab, it is usually described as exercise below the lactate threshold.
Zone 2 is a practical way to build your aerobic base without leaving you too tired for strength training. But definitions differ, and some of the benefits you read online are overstated. Here is what the evidence says.
What Is Zone 2 Cardio?
Zone 2 cardio is low-intensity, steady-state exercise. There is no single official definition. Here are the two most common ways to set it.
- By heart rate: Five-zone systems on many watches, such as Garmin’s default zones, set Zone 2 at 60 to 70% of your maximum heart rate (MHR). Garmin describes it as a comfortable effort where you can still talk with some ease.
- By lactate: Researchers usually describe Zone 2 as low-intensity exercise below the lactate threshold (Sports Medicine, 2025). Lactate is a by-product of breaking down carbohydrate for energy. Below this point, blood lactate stays low and steady.
How to estimate your Zone 2 heart rate: (220 − your age) × 0.6 to 0.7.
Example: If you’re 30 years old, 220 − 30 = 190. Your Zone 2 range is about 114 to 133 beats per minute (bpm).
Feels like: A comfortable pace where you can talk in full sentences without gasping for breath.
Why Zone 2 Definitions Differ
“Zone 2” does not mean the same thing in every system. That matters when you compare apps or read studies.
| System | How zones are set | What “Zone 2” means |
|---|---|---|
| Five-zone heart rate model (common on watches) | Percent of maximum heart rate | 60 to 70% of max heart rate |
| Three-zone research model | Lactate or breathing (ventilatory) thresholds | Around the lactate threshold, about 4 mmol/L. This is harder than watch Zone 2. Easy work at or below about 2 mmol/L is Zone 1 in this model. |
| Public health guidelines | Moderate or vigorous | No Zone 2 as such. Moderate activity means you can talk, but not sing. |
The three-zone model is described in a review of endurance training intensity. The talk test comes from the NHS activity guidelines. So when a study says athletes spend most of their time in “Zone 1”, it often means the same easy pace that a watch calls Zone 2.
Heart rate formulas are only estimates
The 220 − age formula is a rough guide. A study of healthy adults proposed 208 − (0.7 × age) as a better fit. It found that 220 − age overestimates maximum heart rate in younger adults and underestimates it in older adults. The two formulas give about the same answer at age 40. Individual values also varied by around 10 bpm either side of the predicted number.
A 2020 review of exercise intensity methods also found that fixed percentages of maximum heart rate do not reliably put different people at the same intensity. So use the talk test alongside your watch. If you can’t speak in full sentences, slow down.
Does Zone 2 Burn More Fat?
At lower intensities, your body gets a larger share of its energy from fat. As intensity rises, it relies more on carbohydrate (stored as glycogen). A lab study in trained men found that fat burning peaked at about 64% of VO2max, or about 74% of maximum heart rate. Fat burning dropped sharply above that point. VO2max is the most oxygen your body can use during hard exercise.
That peak sits a little above the 60 to 70% range many watches call Zone 2, and it varies from person to person.
Fitness also changes how you use fuel. A study of professional endurance athletes and less-fit people found the athletes burned more fat and had lower blood lactate during exercise. That shows a link between fitness and fuel use. It does not prove that Zone 2 training alone caused the difference.
Keep one more point in mind. Burning a higher share of fat during a session is not the same as losing more body fat. Fat loss depends on your overall energy balance and habits over weeks and months.
Builds Your Aerobic Base and Endurance
Zone 2 builds your aerobic base, the fitness that lets you keep going for longer at a steady pace. In a review of elite endurance athletes, about 80% of training sessions were done at low intensity, at a blood lactate of about 2 mmol/L. Most of the remaining sessions were hard intervals. Those athletes trained 10 to 13 times a week.
Most people have far less time than that. A 2025 review concluded that current evidence does not support Zone 2 as the best intensity for improving mitochondrial capacity in the general population. Mitochondria are the parts of your cells that produce energy aerobically. The review suggested higher intensities may give more benefit when training time is limited.
So Zone 2 is a useful tool, not the only kind of cardio worth doing. A mix of easy sessions and some harder efforts suits most people.
Easier to Recover From
Because the effort is low, most people can do Zone 2 often without feeling drained. That makes it a practical way to add cardio while keeping energy for your strength sessions. It also works well as an easy day between harder workouts.
If you’re doing both on the same day, see how to combine cardio and weights in one day and whether to do cardio or weights first.
How to Add Zone 2 Cardio to Your Routine
The NHS recommends at least 150 minutes of moderate activity a week, or 75 minutes of vigorous activity. It also recommends strengthening activities on at least 2 days a week. Zone 2 sessions done at a talking pace count toward the moderate target.
- 3 to 4 sessions per week of 30 to 60 minutes is a common way to fit it in.
- Choose steady activities: brisk or uphill walking, jogging, cycling, rowing or swimming.
- Pair it with strength training for better all-round fitness. See hybrid training for strength and endurance.
Example weekly plan
- Monday: Strength training + 30 minutes of Zone 2 cardio.
- Wednesday: 45 minutes of Zone 2 cardio.
- Friday: Strength training + 30 minutes of Zone 2 cardio.
- Sunday: 60-minute easy walk or bike ride.
That adds up to about 165 minutes of moderate activity plus two strength sessions. Adjust it to fit your week.
If you use a watch for heart rate, read our guide to wearable tech and strength training, which covers how accurate wrist heart rate is.
If you have a heart condition, or take medication that affects your heart rate, check with your doctor before using heart rate zones.
The Takeaway: A Useful Tool, Not a Magic Zone
Zone 2 cardio is steady, conversational exercise. It builds your aerobic base and is easy to recover from, which makes it a good partner for strength training. Definitions vary, so use the talk test as well as a heart rate number. And don’t skip harder sessions entirely if your time is limited.
Want strength sessions that fit around your cardio? 12REPS builds each workout around your goal, equipment and time. It also remembers what you lifted, so you have a number to beat.
Sources
- About heart rate zones (Forerunner 245 owner’s manual). Garmin, n.d.. https://www8.garmin.com/manuals-apac/webhelp/forerunner245245music/EN-SG/GUID-931BB1F6-0716-4387-9EB0-E6EEDBF5DD09-9894.html
- The training intensity distribution among well-trained and elite endurance athletes. Frontiers in Physiology (Stöggl TL, Sperlich B), 2015. https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2015.00295/pdf
- Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology (Tanaka H, Monahan KD, Seals DR), 2001. https://webs.um.es/jlyuste/documts/tanaka.pdf
- An examination and critique of current methods to determine exercise intensity. Sports Medicine (Jamnick NA, Pettitt RW, Granata C, Pyne DB, Bishop DJ), 2020. https://link.springer.com/content/pdf/10.1007/s40279-020-01322-8.pdf
- Determination of the exercise intensity that elicits maximal fat oxidation. Medicine and Science in Sports and Exercise (Achten J, Gleeson M, Jeukendrup AE), 2002. https://research.birmingham.ac.uk/en/publications/determination-of-the-exercise-intensity-that-elicits-maximal-fat-
- Assessment of metabolic flexibility by means of measuring blood lactate, fat, and carbohydrate oxidation responses to exercise in professional endurance athletes and less-fit individuals. Sports Medicine (San-Millán I, Brooks GA), 2018. https://link.springer.com/10.1007/s40279-017-0751-x
- What is best practice for training intensity and duration distribution in endurance athletes?. International Journal of Sports Physiology and Performance (Seiler S), 2010. https://pubmed.ncbi.nlm.nih.gov/20861519/
- 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/
- Physical activity guidelines for adults aged 19 to 64. NHS, 2024. https://www.nhs.uk/live-well/exercise/physical-activity-guidelines-for-adults-aged-19-to-64/
