Your zone 2 is the easy band just below your first threshold: the point where your breathing starts to deepen and talking gets harder. A panel of 14 sport scientists and coaches agreed on that definition in 2025 (Sitko and colleagues). No formula finds it exactly. A good starting estimate is 60 to 70 percent of your heart-rate reserve, checked against the talk test, then adjusted to how the runs actually feel.
- 18,712people pooled to replace 220 minus age with 208 minus 0.7 × ageTanaka et al. 2001
- 14sport scientists and coaches agreed where zone 2 sits: just below the first thresholdSitko et al. 2025
- ~75%of endurance sessions below the first threshold in well-trained junior skiersSeiler & Kjerland 2006
Why zone 2 works is in what is zone 2 training?, and how zones are drawn in what are heart rate zones? This guide is the practical part.
Four ways to find your zone 2 range
The same runner can get ranges 15 to 20 beats apart depending on the method, which is why zone 2 numbers online disagree.
One runner, three formulas, three zone 2s
- Percent of maximum heart rate. Zone 2 is often given as 60 to 70 percent of your maximum. With a maximum of 180, that is 108 to 126 bpm. Simple, but it ignores your resting rate.
- Heart-rate reserve (Karvonen). Reserve is your maximum minus your resting rate (Karvonen and colleagues, 1957). Zone 2 is usually 60 to 70 percent of that reserve, added back on top of your resting rate. With a maximum of 180 and a resting rate of 55, the reserve is 125, and zone 2 is about 130 to 143 bpm.
- A threshold test. A lab test measuring blood lactate or breathing gases finds your first threshold directly, and zone 2 sits just under it. In the field, a common shortcut is a 30-minute solo time trial: your average heart rate over the last 20 minutes approximates your lactate-threshold heart rate. On Joe Friel's widely used running scale, zone 2 is 85 to 89 percent of that number.
- The talk test. If you can speak in full sentences comfortably, you are usually below the first threshold; once speech gets broken, you are usually above it (Reed and Pipe, 2014). It also moves with you on hot and tired days, which a fixed number cannot.
The practical answer: take the reserve range as your starting number, run a few easy sessions, and lower the top if you cannot hold a conversation at it.
The weak link: your maximum heart rate
Both formula methods depend on your maximum. The familiar 220 minus age was never derived from a proper study (Robergs and Landwehr, 2002). Tanaka and colleagues (2001), pooling 351 studies and 18,712 people, proposed 208 minus 0.7 times age instead. The two agree around age 40 and part with age: at 60, 160 versus 166. Either way, a real maximum often sits 10 beats or more from the formula, and a maximum 10 beats off moves the top of a reserve-based zone 2 by about 7.
The highest heart rate you have actually recorded at the end of a hard race or climb is usually better than any formula. If you are new to exercise or have a heart condition, ask a doctor before any all-out test.
Running zone 2 with Apple Watch
Apple's user guide says Apple Watch Heart Rate Zones are a percentage of your maximum heart rate, calculated and personalised automatically from your health data, and only calculated if your date of birth is in the Health app. Apple does not publish the exact formula.
- During a run: start an Outdoor Run in the Workout app and turn the Digital Crown to the Heart Rate Zone view. It shows your current zone, heart rate, time in that zone and average heart rate.
- Your own range: on the watch, open Settings, Workout, Heart Rate Zones and tap Manual (or My Watch, Workout, Heart Rate Zones in the Watch app on iPhone). You can set the lower and upper limits of zones 2, 3 and 4, so you can type in the range you worked out above.
- Afterwards: in the Fitness app, open the workout and tap Show More next to Heart Rate to see the estimated time in each zone.
Why zone 2 feels too slow
Almost everyone who starts running by heart rate finds zone 2 slower than their usual easy pace. For newer runners the first threshold can sit at a gentle jog, so staying under it may mean walking the hills. That is expected. Run by heart rate and breathing, let pace be whatever it is, and check again in six to eight weeks; easy pace at the same heart rate usually creeps up as your aerobic base grows.
Run by heart rate and breathing, and let pace be whatever it is.
Heat, hills and cardiac drift
On a long steady run, heart rate keeps rising while the heart pumps less blood per beat. This is cardiovascular drift, and heat and fluid loss make it larger (Coyle and González-Alonso, 2001). On a warm day you can drift out of zone 2 at a pace that was easy a week earlier. More in why heat raises your heart rate.
Hills do the same in seconds. Either slow down or walk to stay under the top of your range, or accept some drift late in the run and keep the effort conversational. How much heart rate rises against pace over a run is itself a useful read; see what is durability?
How much of the week to keep easy
Seiler and Kjerland (2006) found well-trained junior cross-country skiers did about 75 percent of their endurance sessions below the first threshold. Seiler's 2010 review described the same mostly-easy pattern across endurance sports, roughly 80 percent easy: the origin of "80/20".
That is an observed pattern in trained athletes, not a quota. A 2024 meta-analysis found polarised training gave a small edge in VO2max, mainly in highly trained athletes, and was otherwise similar to other mixes (Silva Oliveira and colleagues). A 2025 review concluded that zone 2 is not uniquely better than harder work for fitness, especially with little training time (Storoschuk and colleagues). A sensible default: most minutes easy, some harder work when you are ready. See what is effort mix?
Honest caveats
- Wrist heart rate lags. Optical sensors read well at steady effort but can trail sudden changes. In a 2017 study, a chest strap agreed with ECG most closely and wrist accuracy varied by exercise type (Gillinov and colleagues). For steady zone 2 running this matters little.
- Your zone 2 moves day to day. Heat, poor sleep, caffeine and illness lift heart rate at the same effort. On those days, trust the talk test.
- Medicines matter. Beta blockers and some other drugs blunt heart rate, so standard zones do not apply. This page is general information, not medical advice.
How Aera does this
Pace beside heart rateAfter a run, Aera puts your average pace and average heart rate over your usual for the same kind of workout from the last 30 days, once there are three to compare. The same heart rate at a quicker pace, week after week, is the aerobic base growing.
Aera, for iPhone and Apple Watch
Aera draws five heart-rate zones from your own numbers and shows where each workout's minutes landed. By default it uses heart-rate reserve: Zone 2, labelled Easy, is 60 to 70 percent of the room between your resting and maximum heart rate. The maximum is the highest plausible beat on one of your workouts in the last 12 months, shown with the device and day. The resting rate is the middle of up to 45 days of Apple Health's resting readings. Until those exist, the zones screen says Estimated rather than calling the zones yours.
Under Settings, Workouts, Heart rate zones you can switch to percent of max, lactate threshold (from your own 30-minute test) or five boundaries of your own, and type in your own maximum and resting rate. Apple Health does not share the Fitness app's zone table, so Aera cannot read zones you set on the watch; you can enter the same boundaries.
After a workout, Where your heart worked shows time in each zone, counted by time with pauses left out. Outdoors, a short caption under the zone bars notes when the weather was warmer or cooler than you usually train in, and longer runs show heart drift between the two halves, marked steady under 5 percent. Effort zones on the Fitness tab folds each week into easy, moderate and hard and compares it with your own usual weeks, with no 80/20 target line. All of this is free. There is no account, and health numbers are worked out on your iPhone.
Aera is not a medical device.
Quick answers
What is my zone 2 heart rate?
Zone 2 is the easy band just below your first threshold, where your breathing starts to deepen. A practical estimate is 60 to 70 percent of your heart-rate reserve: take your maximum minus your resting rate, multiply by 0.6 and 0.7, and add your resting rate back. With a maximum of 180 and a resting rate of 55, that is about 130 to 143 bpm. Check it with the talk test: you should still manage full sentences.
How do I run in zone 2 with Apple Watch?
Start an Outdoor Run in the Workout app and turn the Digital Crown to the Heart Rate Zone view, which shows your current zone, heart rate and time in that zone. Apple calculates the zones from your health data and needs your date of birth in the Health app. To use your own range, choose Manual under Settings, Workout, Heart Rate Zones.
Why does zone 2 running feel so slow?
For many runners, especially newer ones, the first threshold sits at a gentle jog, so holding zone 2 can mean walking the hills. Heart rate also climbs during a long or warm run at the same pace. Run by heart rate and breathing rather than pace; easy pace usually gets quicker over weeks to months.
How much of my running should be in zone 2?
Endurance athletes typically do roughly three quarters to four fifths of their sessions at easy intensity, below the first threshold. That is an observed pattern, not a rule. If you have little time to train, harder sessions matter too, so most minutes easy with some harder work is a sensible default.
Related field notes: what zone 2 training is · what heart rate zones are · why heat raises your heart rate · what durability is · what effort mix is
Related guide: Should I run after a bad night's sleep?
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;20(11):1614-1617.
- Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology. 2001;37(1):153-156.
- Robergs RA, Landwehr R. The surprising history of the "HRmax = 220 - age" equation. Journal of Exercise Physiology Online. 2002;5(2):1-10.
- Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate: a longitudinal study. Annales Medicinae Experimentalis et Biologiae Fenniae. 1957;35(3):307-315.
- Friel J. Joe Friel's quick guide to setting zones. TrainingPeaks, accessed October 2026. Running zones as percentages of lactate-threshold heart rate from a 30-minute field test.
- Reed JL, Pipe AL. The talk test: a useful tool for prescribing and monitoring exercise intensity. Current Opinion in Cardiology. 2014;29(5):475-480.
- Apple Inc. View Heart Rate Zones on Apple Watch. Apple Watch User Guide. support.apple.com, accessed October 2026.
- Coyle EF, González-Alonso J. Cardiovascular drift during prolonged exercise: new perspectives. Exercise and Sport Sciences Reviews. 2001;29(2):88-92.
- Seiler KS, Kjerland GØ. Quantifying training intensity distribution in elite endurance athletes: is there evidence for an "optimal" distribution? Scandinavian Journal of Medicine and Science in Sports. 2006;16(1):49-56.
- Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance. 2010;5(3):276-291.
- Silva Oliveira P, Boppre G, Fonseca H. Comparison of polarized versus other types of endurance training intensity distribution on athletes' endurance performance: a systematic review with meta-analysis. Sports Medicine. 2024;54(8):2071-2095.
- Storoschuk KL, Moran-MacDonald A, Gibala MJ, Gurd BJ. 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;55(7):1611-1624.
- Gillinov S, Etiwy M, Wang R, et al. Variable accuracy of wearable heart rate monitors during aerobic exercise. Medicine and Science in Sports and Exercise. 2017;49(8):1697-1703.