What is VO2max & How to Improve It

By R.Davies, PhD・Exercise
Published on March 16, 2026

VO2max is your body's maximum capacity to use oxygen (which is usually done during exercise). It is one of the most powerful predictors of both athletic ('endurance') performance and also your long-term health prospects. 

The higher your VO2max, the fitter you are! In this article, we’ll cover what VO2max is, what values are considered healthy, why it matters, and what training methods are most effective at increasing it.

What Is VO2max?

VO2max is shorthand for maximal oxygen uptake: the highest rate at which your body can use oxygen. It is measured in litres of oxygen per minute (L/min), or (more commonly) millilitres per kilogram of body weight per minute (mL/kg/min) to account for different body sizes. 

All things being equal, a larger person will have a larger VO2max (L/min) because they have larger lungs, a larger heart, and more cells, which use more oxygen. This is why scientists correct for body size by dividing it by body mass ('per kg').  

The best way to think of VO2max is the engine size (of your cardiovascular system): the bigger your VO2max, the more oxygen your muscles can use to create energy, and so the faster or longer you can keep exercising [1]. Your VO2max is determined partly by genetics (about half of it). But it also responds strongly to training [2]. Things like how well your heart and blood vessels circulate oxygen-rich blood and how efficiently your muscles use the oxygen can be improved with the right type of regular exercise.

How VO2max Changes: The Physiology

“Oxygen Output”

For most people, the strength and stamina of the heart is the limiting factor that determines VO2max. Exercise training can increase the amount of oxygen-rich blood your heart can pump to your muscles. Just like other muscles in your body, your heart can get bigger and stronger when regularly asked to work hard. 

A well-trained athlete can pump nearly twice as much blood (per beat) as an unfit person. This is why an athlete's resting heart rate is usually a lot lower, because it pumps more blood per beat even when resting.   

“Oxygen Delivery”

Regular exercise training stimulates the growth of new blood vessels around your muscles, meaning it can be delivered more easily. Exercise also increases the amount of blood you have, so it can carry more oxygen. So, more blood plus more blood vessels means more oxygen ends up getting delivered to your muscles.  

“Oxygen Extraction” 

Regular exercise can also increase how much oxygen your muscles can extract (and use) from your blood. The way it does this is by increasing the number and density of small 'organelles' in the muscle called mitochondria. The more mitochondria you have, the more oxygen you can use, the more energy you make, and the longer and harder you can exercise.  

Why does VO2max decline?

Half of the battle throughout life is preventing your VO2max from decreasing, and there are three main ways that it does this.

Detraining

As little as two weeks of inactivity can reduce how well your heart pumps blood, the amount of blood you have and how well your muscles extract oxygen. Saying physically active is probably the most important thing you can do to maintain your VO2max. 

Ageing

Unfortunately, your VO2max starts to drop as you age. You can slow the decline, but you can’t stop it entirely. That's life. Your heart, blood vessels and muscles get worn out over time and work less efficiently. 

Injury or Illness 

Most long-term illnesses or serious acute ones (particularly ones that affect your heart, lungs or require bed rest) will cause quite quick and dramatic decreases in your VO2max. The good news is that when you recover from them, you can regain losses. 

Why VO2max Matters for Your Health

Beyond exercise performance, VO2max is one of the strongest predictors of overall health, heart health, metabolic health, brain health, healthy ageing, physical function, quality of life and life expectancy [3]. In fact, some researchers argue that VO2max is the most useful measure of health, more important than many standard blood tests or resting measures for predicting long-term overall health. 

What Is a Good VO2max for Your Age?

Although VO2max naturally declines with age, those who regularly exercise will have better scores than their younger sedentary peers. The table below gives some general benchmarks for adults (in mL per kg per minute) [4]. 

How to Improve Your VO2max

The science is clear: both high and moderate-intensity training reliably increase VO2max across virtually all types of people [4]. High-intensity style training sometimes delivers faster gains, but most types of exercise are effective.

1. High-Intensity Interval Training (HIIT)

'HIIT' involves alternating short bursts of near-maximal effort with rest-recovery periods. It’s probably the most 'time-efficient' way to increase your VO2max. Slightly longer intervals (≥2 minutes), higher session volumes (≥15 min of total high-intensity work), and programmes lasting at least 4 weeks deliver the greatest VO2max gains.

Try This: 4 intervals of 4 minutes at 90% max effort, with equal-length recovery jogs between, 4 times per week. If you’re just beginning, you can build up to this '4×4×4' workout with '2×2×2' or '3×3×3' workouts.

2. Sprint Interval Training (SIT)

'SIT' uses all-out 100% efforts of 20–60 seconds separated by rest-recovery periods. 

It requires less total training time than HIIT while producing comparable increases in your VO2max. 

The famous 'Tabata' workout (20 seconds on, 10 seconds off, 8 rounds) is one of the best-known SIT workouts [5].

3. Moderate-Intensity Continuous Training (MICT)

Traditional endurance training at a comfortable, but not easy pace (60-75% max effort) is also effective, and some people find it easier than high-intensity training. Why not mix it with HIIT or SIT?

4. Resistance Circuit Training

Circuit-style resistance training, which involves lifting weights or body weight exercises with little rest, can improve both strength and your VO2max [6]. However, if you’re purely looking at improving your VO2max, HIIT, SIT and MICT are more efficient.

How to Estimate Your VO2max at Home

Directly measuring your VO2max requires fancy, expensive equipment and a knowledgeable professional on hand. Fortunately, there are a couple of easy 'proxy' tests you can use to estimate your VO2max. One being your 1.5-mile run time. The second being how far you can run in 12-minutes.

FAQ

Can walking increase your VO2max?

For beginners, regular brisk walks can improve your VO2max. For people who are already quite fit and training at higher intensities, probably not. To increase your VO2max, you need to train at least 60% of your max effort, and secondly, you probably need to train harder than you’re normally used to exercising.

Does diet affect your VO2max?

In our opinion, there is no single food or supplement that has strong, high-quality evidence that directly improves your VO2max. However, diet can affect your VO2max indirectly. You need iron to help your blood carry oxygen. You need carbohydrates and fats to fuel exercise. And some recovery or performance-enhancing supplements can also support exercise-induced increases in VO2max when taken alongside training. 

Does cold weather affect VO2max?

In theory, the weather conditions shouldn’t affect your VO2max. However, the conditions you exercise in may affect your performance or your ability to exercise hard enough to reach your VO2max. So, if you’re testing your VO2max, try to do it in the same conditions each time.

Does alcohol affect VO2max?

Habitual moderate to heavy drinking will reduce your VO2max as it damages your cardiovascular system. It will also impair your exercise performance and recovery. Occasional social drinks at low levels (under 2 pints of beer or glasses of wine) are unlikely to impact gains [7].

How accurate are smartwatches for estimating VO2max?

They are reasonably precise and can probably be used to track whether your VO2max is going up or down if you’re that way inclined. However, in our opinion, you are better off saving your money and tracking your performance data instead. Measure how far, how fast or how easy the workout was. If your watch tells you your VO2max has increased, but your 5k time hasn't changed (or got worse), does it really matter?

How quickly can you increase your VO2max?

With a well-structured exercise programme, you can see improvements in VO2max in a month or two. Clear gains can be seen after two to three months of training. Over time, as you get fitter and reach your genetic ceiling, you’ll get diminishing returns.

Key Takeaways

Optimising your VO2max is one of the most impactful things you can do to support your fitness and health. People with higher VO2max will have healthier lungs, heart, blood vessels and muscles. All these organs respond to the same thing: regular moderate to high-effort exercise of any duration. It will work for nearly everyone regardless of age or fitness level. So, start where you are, be consistent, and your engine will improve.

Sources

1. 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 Oct;45(10):1469-81. PMID: 26243014

2. Bouchard C et al. Familial aggregation of VO(2max) response to exercise training: results from the HERITAGE Family Study. J Appl Physiol (1985). 1999 Sep;87(3):1003-8. PMID: 10484570

3. Strasser B, Burtscher M. Survival of the fittest: VO2max, a key predictor of longevity? Front Biosci (Landmark Ed). 2018 Mar 1;23(8):1505-1516. PMID: 29293447

4. Rapp D et al Reference values for peak oxygen uptake: cross-sectional analysis of cycle ergometry-based cardiopulmonary exercise tests of 10 090 adult German volunteers from the Prevention First Registry. BMJ Open. 2018 Mar 5;8(3):e018697. PMID: 29506981

5. Crowley E et al. The Effect of Exercise Training Intensity on VO2max in Healthy Adults: An Overview of Systematic Reviews and Meta-Analyses. Transl Sports Med. 2022 Feb 24;2022:9310710. PMID: 38655159

6. Muñoz-Martínez FA, et al. Effectiveness of Resistance Circuit-Based Training for Maximum Oxygen Uptake and Upper-Body One-Repetition Maximum Improvements. Sports Med. 2017;47:2553-2568. PMID: 28822112

7. Barnes MJ. Alcohol: impact on sports performance and recovery in male athletes. Sports Med. 2014 Jul;44(7):909-19. PMID: 24748461

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Published: March 16, 2026

Lead Author: R.Davies, PhD | Author Bio

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