Zone 2 cardio is endurance exercise at a conversational pace, close to but below the first ventilatory threshold: 20 to 30 minutes, three times a week, is a practical starting point for a beginner. A range of 60 to 70% of maximum heart rate is just a watch convention: at age 40, it would give roughly 108 to 126 bpm, without measuring your actual threshold.
This guide covers calculations, pace and sessions, whether you walk, cycle or run. For device menus, use the guide Garmin Zone 2: max HR, reserve and threshold · FR. Your watch shows a clear boundary. Your metabolism didn’t get the memo.
Zone 2 cardio: what is it really?
Two models use the same name for different intensities:
- the three-zone model places the low zone below the first threshold, the middle zone between the two thresholds and the high zone above the second
- the five-zone model divides intensity further and often calls a watch-calculated range Zone 2
A panel of fourteen scientists and coaches proposed in 2025 that Zone 2 be defined as an intensity immediately below the first lactate or ventilatory threshold. The experts also note that the expected adaptations are not exclusive to it and can occur slightly below or above it.
This explains why two apps give different ranges using the same data. Before adjusting your training, check whether the algorithm uses maximum HR, heart rate reserve or a measured threshold.
Calculating Zone 2 using maximum heart rate
Step 1: estimate or measure maximum HR
The Tanaka formula, developed in healthy adults, provides this population-level reference:
Estimated max HR = 208 − 0.7 × age
For a 40-year-old:
208 − 0.7 × 40 = 180 beats per minute
This value is a statistical average. Two people of the same age can have very different actual maximum heart rates. Max HR is not a fitness score and does not drop simply because training is working.
A maximal exercise test is not required before your first gentle session. When it is appropriate and what precautions to take should be discussed with a professional, as explained in the safety section.
Step 2: apply your watch’s method
If your device defines Zone 2 as 60 to 70% of max HR, the calculation for the 180 bpm example gives:
- lower limit: 180 × 0.60 = 108 bpm
- upper limit: 180 × 0.70 = 126 bpm
This range is easy to calculate, but may be too low or too high relative to your individual first threshold. A study of 50 cyclists found substantial variability between fixed Zone 2 markers. Percentages of max HR aligned less well with individual physiology than the first ventilatory threshold and the point of maximal fat oxidation.
Zone 2 chart by age: an estimate, not a target
Here is the arithmetic result of the Tanaka formula using the 60 to 70% of max HR convention, rounded to the nearest beat:
| Age | Estimated max HR | Range at 60–70% of max HR |
|---|---|---|
| 20 years | 194 bpm | 116–136 bpm |
| 30 years | 187 bpm | 112–131 bpm |
| 40 years | 180 bpm | 108–126 bpm |
| 50 years | 173 bpm | 104–121 bpm |
| 60 years | 166 bpm | 100–116 bpm |
This chart gives neither a “women’s” nor a “men’s” zone: age is used for an average estimate, not to determine an individual threshold. Do not use these ranges if your app calculates zones using heart rate reserve.
How do you calculate Zone 2 with Karvonen?
The Karvonen method uses heart rate reserve:
Heart rate reserve = max HR − resting HR
Then:
Target HR = resting HR + percentage × heart rate reserve
With a max HR of 180 bpm and a resting HR of 60 bpm:
- reserve: 180 − 60 = 120
- at 60%: 60 + 0.60 × 120 = 132 bpm
- at 70%: 60 + 0.70 × 120 = 144 bpm
The range of 132 to 144 bpm is very different from the 108 to 126 bpm obtained using a percentage of max HR. No calculation error has been made. The two methods simply do not calculate a percentage of the same thing.
So do not select “60 to 70%” without checking the formula. The heart rate zone calculator makes the calculation easier, but the talk test is still needed to check the result in practice. To apply this check to your watch, follow the guide Garmin Zone 2: max HR, reserve and threshold · FR.
Measuring resting HR correctly
Measure it on several mornings, lying down or sitting under the same conditions, before coffee and activity. Use the average rather than a single day. An infection, a poor night’s sleep, heat, dehydration and stress can change it.
The American Heart Association fact sheet notes that certain medications and illnesses affect heart rate. These specific cases are covered in the safety section.
Talk test: the simplest guide
A review of the talk test concludes that comfortable conversation generally remains possible below the ventilatory or lactate threshold. It becomes difficult above it.
During a Zone 2 session, you should notice the following:
- full sentences are still possible
- deeper breathing than at rest
- easy to moderate perceived effort, with no required rating on a scale
- a sense that you can keep going without a constant mental battle
If you can only say a few words, slow down. If the effort feels very easy, assess speech, duration and perceived effort together before chasing a higher number.
The talk test does not require you to speak without anyone noticing the effort. What matters most is that speech remains comfortable and continuous.
Ventilatory threshold, lactate and FatMax
Laboratory testing
An exercise test with gas analysis can identify the first ventilatory threshold, or VT1. This is the most consistent reference for individualizing the upper limit. An incremental lactate test can also estimate the first lactate threshold.
The fixed value of 2 mmol/L is a simplification. Resting lactate, lactate kinetics and the threshold vary between individuals. A single finger-prick measurement without a progressive protocol does not precisely define the zone.
FatMax is not always exactly Zone 2
FatMax is the intensity at which absolute fat oxidation peaks during a given test. In the 2025 cyclist study, FatMax and VT1 were fairly well aligned, without being identical in every participant.
Using more fat during a session does not mean losing more body fat over several weeks. Energy balance, diet and adherence remain key.
How many minutes and Zone 2 sessions per week?
The following progression is an editorial framework for consistency, not an optimal dose demonstrated in a trial or a medical prescription:
| Level | Frequency | Duration per session | Intensity |
|---|---|---|---|
| Sedentary beginner | 3 times per week | 20 to 30 min | Easy talk test, lower end of the estimated range |
| Regularly active | 3 times per week | 30 to 45 min | Just below the point where comfortable speech becomes difficult |
| Recreational endurance | 3 to 5 times per week | 40 to 75 min | Below VT1, volume adapted to the sport |
| Trained athlete | According to the training plan | 45 to 120 min | Measured threshold, load and recovery monitored |
Start with a volume you can repeat the following week. First increase the duration of one or two sessions, and only then the number of sessions. If sleep, mood, pain or performance worsen for several days, reduce the load.
The WHO recommends 150 to 300 minutes of moderate aerobic activity per week for adults, or the equivalent combined with vigorous activity. Not all of that time needs to be a formal Zone 2 session.
A typical session, from start to finish
On a bike, on a treadmill or outdoors, start with five easy minutes. Then spend twenty minutes at an intensity where you can say several full sentences. Finish with five slower minutes. This example lasts thirty minutes in total, including twenty at the working intensity: warm-up minutes should not be artificially counted as an extra twenty minutes of Zone 2.
Record the activity, duration, average HR and how comfortable speaking felt. After four to six weeks, compare a similar session in similar weather and with a similar level of fatigue. Going faster at a comparable HR and perceived effort is a practical sign of progress, not a measurement of mitochondria or years of life gained.
A six-week example for beginners
A simple progression could follow this pattern:
- weeks 1 and 2: three sessions of 20 to 25 minutes
- weeks 3 and 4: three sessions of 30 minutes
- weeks 5 and 6: two sessions of 35 to 40 minutes and one of 25 to 30 minutes
Keep a conversational pace. If thirty minutes of walking is enough to reach this intensity, there is no need to run. The comparison between 8,000 steps and 30 minutes of running helps you build a realistic activity volume around your sessions.
Which equipment should you choose?
The best option is the one that allows a steady intensity without pain:
- brisk walking or an inclined treadmill
- indoor or outdoor cycling
- rowing if your technique stays efficient
- elliptical trainer
- slow running for people already accustomed to it
- swimming using pace as a guide rather than wrist HR
Running sometimes raises a beginner’s heart rate too quickly. Alternating walking and running is not a failure. It is a precise way to stay below the threshold.
If wrist readings show erratic spikes, check the sensor’s fit and compare the reading with a chest strap rather than changing your zone based on a single graph. The comparison of wearables for sport and recovery distinguishes measurement tools by their intended use.
Cardiac drift: why HR rises at a steady pace
During a long session, heat and dehydration can raise heart rate even when speed stays the same. This cardiovascular drift has been measured experimentally, but not every increase seen on a watch allows its cause to be isolated.
If you exceed the upper limit and speaking becomes less comfortable, slightly reduce your power or pace. Do not try to maintain your initial pace at the cost of spending a prolonged period above the threshold.
Instead, compare the relationship between speed or power and HR under similar conditions. Improvement shows up when you produce more work at a comparable heart rate and perceived effort.
Zone 2, HIIT or strength training: what should you combine?
Zone 2 mainly lets you accumulate endurance minutes you can repeat consistently. HIIT involves more intense efforts with more recovery. There is no universal winner: the Zone 2 and HIIT comparison · FR covers the choice based on the time available and your VO2 max goal.
If you also do strength training, start with a cardio volume that does not compromise your priority sessions. Tracking active and passive recovery helps distinguish light movement from an additional training load.
Does Zone 2 help you lose weight and live longer?
Aerobic training stimulates mitochondrial, capillary and cardiorespiratory adaptations. The evidence does not show that Zone 2 is the only intensity that does this, or always the best.
A 2025 critical review points out that the concept’s popularity stems partly from the high training volumes of endurance athletes. For the general public with limited time, higher intensity can produce a substantial gain in cardiorespiratory fitness. Zone 2 remains valuable because it allows you to accumulate volume with relatively little fatigue.
The best framework generally combines:
- plenty of easy to moderate activity
- strength training at least two days a week, in line with WHO recommendations
- possibly an intense session after a base-building phase and if your health allows
- adequate recovery
The polarized 80/20 model mainly describes athletes’ training. It is not a mandatory ratio for every adult or a reason to ban all moderate-intensity exercise.
Do you need to fast or breathe only through your nose?
Neither rule defines Zone 2. The panel’s definition is based on the first threshold, not meal timing or mandatory nasal breathing. FatMax refers to fat use during the test, not fat loss over several weeks. The best time is still the one that lets you repeat sessions without compromising sleep or meals.
Safety and when to stop
Some medications, particularly beta-blockers, alter the heart rate response: in that case, discuss any standard formula with the doctor managing your treatment.
Seek medical advice before starting if you have cardiovascular disease, chest pain, unusual breathlessness, feel unwell during exertion, have a known arrhythmia or several risk factors that have not been assessed.
Stop the session if you experience chest pain, feel unwell, have unusual palpitations, sudden weakness or disproportionate breathlessness. If the emergency persists, call 15 or 112.
