VO2 Max: What It Measures and Its Limits

VO2 max is widely used as a measure of cardiorespiratory fitness. It can be informative, but it is not a complete health score and different testing methods can produce different results.

What does VO2 max measure?

VO2 max is the highest rate at which the body can take in, transport and use oxygen during very hard exercise. It reflects the combined work of the lungs, circulation and muscles under the conditions of the test.

How is it measured?

A direct laboratory test measures breathing gases while exercise becomes progressively harder. Field tests and wearable devices usually estimate the value from performance, heart rate or other data. An estimate is not the same as a direct measurement.

Why can results differ?

Marcos Martin-Rincon and José Calbet reviewed methods used to test and interpret VO2 max. They reported that the way breath-by-breath data are averaged can change a result by 4 to 10 per cent. Protocol, equipment calibration, familiarisation and effort can also affect the number.

What can the number tell you?

It can describe performance in a particular test and may be useful when the same method is repeated under comparable conditions. It does not explain every limit on exercise or show all training adaptations.

What are the limitations?

The review was about measurement and interpretation, not a trial of a health program. The authors noted that a lack of change in VO2 max does not prove that no adaptation occurred. Results from different devices or protocols should not be treated as directly interchangeable.

When should testing be discussed with a professional?

Maximal exercise testing is demanding. If you have symptoms, a known condition or concerns about intense exercise, ask a qualified health professional whether testing is appropriate and how the result should be interpreted.

References

• Marcos Martin-Rincon and José A. L. Calbet. “Progress Update and Challenges on VO2 Max Testing and Interpretation.” Frontiers in Physiology. 2020;11:1070. DOI. Free full text. The work was supported by Spanish public research grants. The authors declared no commercial or financial conflict of interest.

This article provides general health information. It does not assess fitness, recommend a test or clear anyone for strenuous exercise. A qualified professional can advise whether a test is appropriate for you.