What is VO₂Max?

VO₂Max (maximal oxygen uptake) is the maximum amount of oxygen your body can take in per minute during exercise. It is used as a measure of cardiorespiratory fitness.

What happens inside your body

Japan's Ministry of Health, Labour and Welfare (MHLW) describes cardiorespiratory fitness as the ability to take oxygen from the air through the lungs, deliver it through the blood pumped by the heart, and use it in working muscles to break down sugars and fats to produce energy for exercise.

VO₂Max therefore reflects the combined functions of the lungs, the heart and blood, and the muscles. In an eight-week study of 40 men who exercised regularly, training-related increases in VO₂Max corresponded to increases in the amount of blood pumped by the heart with each beat (stroke volume) (Helgerud et al., 2007).

Converting units

• mL/kg/min: The millilitres of oxygen used per minute per kilogram of body weight. This is the main unit used on this site.
• METs: A unit of physical activity intensity. Cardiorespiratory fitness values or reference values expressed in METs can be multiplied by 3.5 to convert them to oxygen uptake (mL/kg/min). For example, a fitness reference value of 10 METs corresponds to 35 mL/kg/min.

One study describes a difference of 1 MET in cardiorespiratory fitness as equivalent to a difference of approximately 1 km/h in running speed (Kodama et al., 2009).

VO₂Max and VO₂peak

You may encounter both VO₂Max (maximal oxygen uptake) and VO₂peak (peak oxygen uptake) in documents and smartwatch displays. VO₂Max is the true maximum, where oxygen uptake stops increasing even as the workload rises. VO₂peak is the highest value observed during the exercise test actually performed.

MHLW states that VO₂peak, like the more strictly measured VO₂Max, is a strong predictor of mortality and disease incidence. This site uses the term VO₂Max unless the distinction is necessary.

Average values differ across age groups

Estimated averages compiled from Japanese research data by sex and age were highest in the 10–19 age group and tended to be lower in successively older groups from the twenties onward. Differences between age groups were larger in the twenties and thirties and smaller from age 40 onward (MHLW, 2023). These findings compare different age groups. They do not track the same people over many years or tell us how quickly an individual's fitness will change (Akiyama et al., 2023).

From this estimated distribution, MHLW explains that approximately half of men in their sixties and women in their forties can sustain an 8-MET activity, such as carrying heavy loads, for at least three minutes. This does not judge an individual's fitness based on age alone. See the age-based reference tables for the averages and reference values.

Why does it matter?

Studies following large numbers of people have repeatedly reported associations between higher VO₂Max and lower risks of mortality and heart disease. Read more about VO₂Max and health.

To find your value, see how to measure it. To work on improving it, see the comparison of exercise methods.