Key takeaways
VO2max work happens in zone 5, about 90 to 100% of max heart rate; zone 2 is about 60 to 70%
Age formulas such as 220 minus age or 208 minus 0.7 times age miss the true max by around 10 to 12 beats on average
Best zones come from a measured max heart rate or lab thresholds; heart-rate reserve zones suit people with a low resting heart rate
For VO2max, two heart-rate zones matter most: zone 5, where the hard intervals happen, and zone 2, where most of the easy volume happens. Here is what the zones mean, how to set them and how far to trust the formulas. To get your own numbers, use the heart rate zone calculator.
VO2max zones: the five-zone model
Most watches and apps, including Garmin by default, use five zones based on a percentage of maximum heart rate:
| Zone | % of max heart rate | Feel | Main purpose |
|---|---|---|---|
| 1 | 50–60% | Very easy, relaxed breathing | Warm-up, recovery |
| 2 | 60–70% | Comfortable, can hold a conversation | Aerobic base |
| 3 | 70–80% | Moderate, talking gets harder | Aerobic endurance |
| 4 | 80–90% | Hard, forceful breathing | Threshold |
| 5 | 90–100% | Very hard, unsustainable for long | VO2max and top-end speed |
VO2max zone meaning
"VO2max zone" usually means the intensity close to your maximal oxygen uptake — zone 5. At this effort your heart pumps near its maximum and your muscles use oxygen as fast as they can. You can only stay there for a few minutes, which is why it is trained with intervals rather than continuous runs.
VO2max zone 5: how much time?
The best-known protocol is the Norwegian 4×4: four 4-minute intervals at 90–95% of max heart rate with 3 minutes of easy recovery. In Helgerud's 2007 study, three sessions a week for eight weeks raised VO2max by about 7% in moderately trained men, more than the same work done at threshold or at 70% of max heart rate.
Two practical points:
- Heart rate lags. In a 4-minute interval it often takes one to two minutes to climb into zone 5. Pace the first minute by effort, not by the number on your watch.
- A little goes a long way. Around 10–20 minutes of hard work per session, once or twice a week, is enough for most people. Elite athletes keep roughly 80% of their training easy (80/20 training).
VO2max zone 2
Zone 2 is the top of the easy range, about 60–70% of max heart rate. It builds the aerobic base that lets you complete and recover from zone 5 sessions. It does raise VO2max, especially in beginners, but less per minute than intervals. See zone 2 training and VO2max and HIIT vs steady cardio.
Zones by % of max vs heart-rate reserve (Karvonen)
The Karvonen method, from a 1957 Finnish study by Karvonen, Kentala and Mustala, uses heart-rate reserve — the gap between resting and maximum heart rate:
Target heart rate = resting HR + % × (max HR − resting HR)
Example: max 185 bpm, resting 55 bpm, so the reserve is 130 beats.
| Zone | % of max HR | % of heart-rate reserve |
|---|---|---|
| Zone 2 (60–70%) | 111–130 bpm | 133–146 bpm |
| Zone 5 (90–100%) | 167–185 bpm | 172–185 bpm |
Reserve-based zones come out higher, especially at the easy end, and shift as your resting heart rate falls. They suit fit people with a low resting heart rate. Use a morning resting value averaged over several days (resting heart rate, HRV and recovery).
VO2max zones by age
Without a measured max, you need an age formula. The classic 220 − age has no solid research origin. Tanaka and colleagues pooled 351 studies with 18,712 people and proposed 208 − 0.7 × age, which is less likely to underestimate max heart rate in older adults. Using Tanaka:
| Age | Estimated max HR (220 − age) | Estimated max HR (Tanaka) | Zone 2 (Tanaka) | Zone 5 (Tanaka) |
|---|---|---|---|---|
| 20 | 200 | 194 | 116–136 | 175–194 |
| 30 | 190 | 187 | 112–131 | 168–187 |
| 40 | 180 | 180 | 108–126 | 162–180 |
| 50 | 170 | 173 | 104–121 | 156–173 |
| 60 | 160 | 166 | 100–116 | 149–166 |
| 70 | 150 | 159 | 95–111 | 143–159 |
These are population averages. In a 2020 test of both formulas against measured max heart rate, the typical error was around 11–12 bpm for 220 − age and 11 bpm for Tanaka — enough to shift every zone. Max heart rate also falls with age regardless of fitness (VO2max and ageing).
Lab threshold-based zones
The most accurate zones come from your own physiology. A lab test identifies your first and second thresholds (ventilatory or lactate) and the heart rate at each. Seiler's three-zone model uses them directly: zone 1 below the first threshold, zone 2 between the two, zone 3 above the second. Note that Seiler's "zone 2" is not the watch's zone 2 — it sits higher. See what a VO2max test costs and what to expect.
Garmin can also set zones from lactate threshold heart rate (LTHR): by default zone 2 is 80–89%, zone 3 89–95%, zone 4 95–100% and zone 5 above 100% of LTHR.
VO2max zones Garmin: setting them up
- Enter a measured max heart rate (from a race finish or a hard hill session) or turn on auto-detection.
- Choose %Max HR, %HRR or %LTHR in the zone settings.
- If you have lab results, enter the threshold heart rates as zone boundaries.
- Recheck every few months. Watch VO2max estimates depend on accurate heart rate, so good zones help those too (how accurate is your watch's VO2max).
Then track your fitness with the VO2max calculator and compare with the VO2max chart.
Safety: zone 5 work is very demanding. If you have a heart condition, take heart-rate-lowering medication or have been inactive, get medical advice before starting high-intensity intervals, and don't chase a max heart rate test alone.
Frequently asked questions
What is the VO2max zone?
It is the intensity close to your maximal oxygen uptake, roughly 90 to 100% of maximum heart rate, which is zone 5 in most five-zone systems including Garmin's default. You can hold it only for a few minutes at a time.
How long should you train in zone 5 for VO2max?
Most research protocols accumulate around 10 to 20 minutes of hard work per session, for example 4 x 4 minutes at 90 to 95% of max heart rate, once or twice a week. Heart rate lags, so it reaches zone 5 only partway through each interval.
How do I calculate my VO2max zones by age?
Estimate max heart rate with 208 minus 0.7 times age, then take 60 to 70% for zone 2 and 90 to 100% for zone 5. At 40 that is about 108 to 126 and 162 to 180 bpm. A measured max heart rate is far more reliable.
How does Garmin set heart rate zones?
By default from your profile and maximum heart rate, as a percentage of max heart rate: zone 1 50 to 60%, zone 2 60 to 70%, zone 3 70 to 80%, zone 4 80 to 90% and zone 5 90 to 100%. You can switch to heart-rate reserve or lactate threshold zones.
Sources
- Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. J Am Coll Cardiol, 2001. Abstract
- Karvonen MJ, Kentala E, Mustala O. The effects of training on heart rate; a longitudinal study. Ann Med Exp Biol Fenn, 1957. PubMed
- Seiler S. What is best practice for training intensity and duration distribution in endurance athletes? Int J Sports Physiol Perform, 2010.
- Helgerud J, et al. Aerobic high-intensity intervals improve VO2max more than moderate training. Med Sci Sports Exerc, 2007. Full text (PDF)
- Shookster D, et al. Accuracy of commonly used age-predicted maximal heart rate equations. Int J Exerc Sci, 2020. Full text
- Robergs RA, Landwehr R. The surprising history of the "HRmax = 220 − age" equation. J Exerc Physiol Online, 2002.
- Garmin: heart rate zone calculations (fēnix 5 manual)
- Garmin: setting your heart rate zones (fēnix 8 manual)