How to improve VO2 max: what it is, how to test it, and how to train
VO2 max is your peak aerobic fitness in ml/kg/min. See what a good number is for your age, how to estimate it, and how to improve it with easy miles and intervals.
revns editorial · Published November 13, 2026 · 8 min read
VO2 max (ml/kg/min) marks aerobic fitness. Raise it with mostly zone 2 cardio, 1–2 weekly interval sessions, strength, and enough sleep and food.
VO2 max is the highest rate your body can use oxygen during hard exercise, measured in millilitres of oxygen per kilogram of body weight per minute (ml/kg/min). It is one of the strongest markers of aerobic fitness and of how much cardiovascular work your training can support. Most active adults raise it by doing mostly easy aerobic training (zone 2 effort), adding one or two hard interval sessions a week, keeping up strength work, and recovering with enough sleep and food — not by training hard every day.
TL;DR
| Topic | Takeaway |
|---|---|
| What it means | Peak oxygen use during maximal effort; higher usually means better endurance |
| Typical range | Often 35–45 ml/kg/min around age 30; declines with age unless you train |
| How to measure | Lab test, field tests (Cooper 12-min run), or watch estimates from pace and heart rate |
| How to improve | 150–300 min/week moderate cardio, mostly easy; 1–2 hard sessions; strength 2×/week |
| Track progress | Same test or VO2 max calculator every 8–12 weeks |
What is VO2 max in plain language?
When you exercise harder, your muscles need more oxygen. Your heart and lungs deliver it through your blood. VO2 max is the point where, even if you push harder, your body cannot use oxygen any faster — you have hit your aerobic ceiling.
In a graded exercise test in a lab, you typically walk or run on a treadmill or cycle while researchers measure the oxygen in your breath. The highest steady value is your VO2 max. That test is the gold standard, but it is not necessary for everyday training.
Outside the lab, field tests (how far you run in 12 minutes, how fast you walk a mile) and heart-rate methods estimate VO2 max. Wearables such as Apple Watch use outdoor walks and runs on fairly flat ground to project oxygen use from pace and heart rate. Those numbers are useful for tracking your own change, not for comparing yourself to a research table or a friend's device.
VO2 max is influenced by:
- Genetics and sex (on average, men tend to have higher values than women at the same training level).
- Age (values usually fall unless aerobic training keeps stimulating the system).
- Body weight (the "per kg" part means losing excess fat can raise VO2 max even if absolute fitness is unchanged).
- Training history (years of consistent easy and hard aerobic work matter).
Association studies link higher cardiorespiratory fitness to lower risk of cardiovascular disease and all-cause mortality in large cohorts. That does not prove that raising your personal number by five points will change your outcomes, but it supports treating aerobic fitness as part of a long-term health habit alongside strength, sleep and food.
What is a good VO2 max number?
Reference tables group people by age and sex. For adults in their 30s, rough bands are often:
| Category | Men (ml/kg/min) | Women (ml/kg/min) |
|---|---|---|
| Below average | Under about 35 | Under about 30 |
| Average | About 35–45 | About 30–38 |
| Good | About 45–55 | About 38–48 |
| Excellent | Above about 55 | Above about 48 |
These cut-offs vary by source and by whether values came from lab tests or estimates. Elite endurance athletes can exceed 70 ml/kg/min; sedentary adults can sit in the 20s. A number only matters alongside your goals: a recreational runner improving from 38 to 44 over a season is a real win even if neither value looks "excellent" on a chart.
If you use a watch estimate, read Apple's own validation work as an example of error: in a validation group of 221 people, the watch read about 1.4 ± 4.7 ml/kg/min above or below Apple's projected reference from submaximal exercise tests — useful for trends, but not the same as a maximal lab test. Beta blockers and other medicines that lower heart rate can make watch estimates read too high unless the device knows you take them.
How do I measure or estimate my VO2 max?
Pick one method and stick with it for trends.
- Heart rate during a steady outdoor walk or run (the idea behind many watches). You need flat ground, several minutes of steady effort, and a heart rate clearly above rest. The VO2 max calculator walks through the same oxygen-cost maths with open equations.
- Cooper 12-minute run. After a warm-up, run as far as you can in 12 minutes on a flat track. The classic formula (Cooper, 1968) converts distance in metres to an estimate: VO2 max ≈ (metres − 504.9) ÷ 44.73.
- 1.5-mile (2.4 km) run test. Time an all-out effort; longer tests suit people who already run.
- Rockport 1-mile walk test. Walk one mile as fast as you can and record finish heart rate; useful if running hard is not an option.
- Resting versus maximum heart ratio (Uth). A rough estimate from resting and maximum heart rate without a run — convenient but less precise.
Retest every eight to twelve weeks under similar conditions: same route, similar weather, well rested, not at the end of a hard training block. Log the result in your training notes or in revns so you see the line over time.
Why does VO2 max matter for training?
Higher VO2 max usually means you can hold a faster pace or higher power at the same heart rate — you have more headroom before you cross into unsustainable effort. That matters for:
- Running and cycling events longer than a few minutes.
- Sports with repeated sprints (football, hockey, court sports), where you recover faster between bursts if your aerobic base is strong.
- Daily life: climbing stairs, hiking, playing with children without gasping.
VO2 max is not the only endurance variable. Lactate threshold, running economy and fuel use also limit performance. Two runners with the same VO2 max can race differently. Still, for most people who are not specialists, raising VO2 max is the main lever for feeling fitter on long efforts.
Easy training also builds the mitochondria and capillaries that support that ceiling. That is why programmes that are almost all hard often stall: you need volume at manageable intensity to support the peaks.
How do I improve VO2 max?
Research in healthy adults roughly 18 to 45 years old comparing high-intensity interval training (HIIT) with moderate continuous training generally finds both raise VO2 max, with HIIT often producing a bit more in head-to-head trials. A 2015 meta-analysis in Sports Medicine pooled 28 controlled trials (~720 participants) and reported larger VO2 max gains with HIIT than with moderate continuous training, especially when intervals were near maximal heart rate. You still need enough total aerobic volume and recovery to absorb the hard days.
A practical, evidence-aligned week for someone who is already walking or jogging a few times:
Build the base (zone 2)
Most of your cardio should feel easy: full sentences, not singing. Zone 2 training at roughly 60–70% of maximum heart rate matches the WHO's moderate intensity band. Adults are advised to get 150 to 300 minutes of moderate aerobic activity per week (or 75–150 minutes vigorous, or a mix), plus muscle-strengthening on two or more days.
Example: three sessions of 30 to 45 minutes of brisk walking, easy running, cycling or swimming in zone 2.
Use the heart rate zone calculator or the talk test if you do not wear a monitor.
Add one hard aerobic session
The 4 × 4 minute interval protocol from Helgerud and colleagues is a well-known model: in one eight-week trial of 40 moderately trained men, four bouts of four minutes at roughly 90–95% of maximum heart rate, with three minutes of easy work between, three times a week, raised VO2 max more than longer slow runs at about 70% max heart rate. After a long warm-up, the same pattern fits many recreational runners when layered on a base of easier training.
Simpler options if you are newer to intervals:
- 6 × 2 minutes hard with 2 minutes easy between.
- 5 × 3 minutes uphill at strong effort, walk down for recovery.
Place hard day at least 48 hours after heavy leg strength work, or on a different day entirely.
Keep strength in the plan
The WHO guidelines count muscle-strengthening on two or more days per week. Strength does not replace cardio for VO2 max, but it supports injury resistance, bone health and the ability to tolerate more running or cycling volume. If you are a beginner, a simple full-body plan two or three times a week is enough.
Sleep, food and consistency
Short sleep and chronic undereating blunt adaptations. Adults need seven or more hours of sleep regularly; people in heavy training often do better at the upper end. Eat enough carbohydrate around hard sessions if you train fasted and feel flat, and enough protein across the day for recovery — see guides on sleep and protein for numbers.
Improvements come from months of mostly easy work with a small share of hard work — not from red-lining every workout.
What should I do this week?
If you are new to structured cardio:
- Walk briskly 30 minutes, three days, at a pace where you can talk in sentences.
- Add two light strength sessions (bodyweight squats, push-ups, rows, glute bridges).
- Note resting heart rate in the morning if you use a watch; a slow downward trend over weeks often tracks improving fitness.
If you already do easy runs or rides three times a week:
- Keep two of those sessions strictly easy (zone 2).
- Replace the third with 4 × 2 minutes uphill or on the flats at 8/10 effort, 2 minutes easy between, once this week only.
- Retest with the Cooper test or the calculator in eight weeks, not tomorrow.
If you use AI assistants with your training data, you can log sessions and ask for a sanity check on easy versus hard distribution through revns MCP — the assistant sees your log, not a lab VO2 max.
When should I see a clinician?
Stop hard testing and get medical advice if you notice:
- Chest pain, pressure or unusual shortness of breath during exercise.
- Fainting, severe dizziness or palpitations with effort.
- A watch VO2 max estimate that drops sharply over a few weeks while you feel unwell (treat symptoms first, not the metric).
- Known heart disease, diabetes with complications, pregnancy complications or recent surgery — ask what intensity is safe before maximal tests.
For mental health crises, contact a local crisis line or emergency services; training stress is not a substitute for care.
Related
- Zone 2 training explained
- How many steps per day do you need?
- What is HRV? Heart rate variability explained
- VO2 max calculator
- Heart rate zone calculator
- Multi-sport tracker
This is general training guidance, not medical advice.
Sources
- Cooper KH. A means of assessing maximal oxygen intake: correlation between field and treadmill testing. JAMA 1968
- Helgerud J et al. Aerobic high-intensity intervals improve VO2max more than moderate training. Med Sci Sports Exerc 2007
- Milanović Z et al. Effectiveness of high-intensity interval training (HIT) and continuous endurance training for VO2max improvements: a systematic review and meta-analysis of controlled trials. Sports Med 2015
- Bull FC et al. World Health Organization 2020 guidelines on physical activity and sedentary behaviour. Br J Sports Med 2020
- Apple. Using Apple Watch to Estimate Cardio Fitness with VO2 max. 2021
Terms in this post
revns publishes training and nutrition guidance, not medical advice. See a clinician for symptoms, injury or a medical condition. Accurate as of November 13, 2026.
