What VO2 max tells you
VO2 max is the maximum volume of oxygen your body can take in and use during all-out exercise, measured in millilitres of oxygen per kilogram of body weight per minute. It reflects how well your heart, lungs and muscles work together and is one of the strongest single predictors of aerobic fitness and long-term health.
The Uth–Sørensen method used here estimates it from the ratio of your maximum to your resting heart rate. A fit heart pumps more blood per beat, which lowers resting heart rate and pushes the ratio, and the estimate, higher.
Getting a useful estimate
The quality of the result depends on the heart-rate figures you feed in.
- Measure resting heart rate first thing in the morning before getting up, ideally averaged over several days.
- If you know your true maximum heart rate from a hard effort or a lab test, enter it instead of relying on the 220 − age estimate.
- The 220 − age rule is only a rough average and can be off by 10 to 20 beats for an individual.
- Re-test under the same conditions so changes reflect fitness, not measurement noise.
Improving your aerobic fitness
VO2 max responds well to training, especially a mix of steady aerobic work to build your base and higher-intensity intervals to push your ceiling. Beginners often see the fastest gains, while well-trained athletes improve more slowly.
It also declines gradually with age, so maintaining a strong figure over the years is itself a meaningful fitness goal.
A note on health
This is a quick estimate, not a clinical measurement, and the fitness category is a general guide that varies with age and sex. A laboratory test directly measures oxygen use for a true figure. Before attempting maximal-effort exercise, particularly if you have a heart condition or are new to intense training, consult a doctor.
Formula
VO2max = 15.3 × (maxHR / restingHR); maxHR = 220 − age if not givenFrequently asked questions
- Is this as accurate as a lab test?
- No. A laboratory VO2 max test directly measures oxygen consumption. The heart-rate ratio method is a quick estimate and the fitness category is a general guide only.