VO2 Max: The Longevity Number Most People Never Check
Cardiorespiratory fitness predicts how long you’ll live as strongly as many diseases do. The good news: it’s one of the most trainable numbers in your body.
Key takeaways
- Low cardiorespiratory fitness is linked to a risk of early death comparable to or greater than smoking or diabetes.
- Moving from the bottom fitness group to the next one up is associated with the biggest gain.
- A mix of steady aerobic work and harder intervals is the most reliable way to raise VO2 max.
VO2 max is the maximum amount of oxygen your body can use during all-out effort. It reflects how well your heart, lungs, blood vessels and muscles work together, and it turns out to be one of the strongest predictors of how long people live.
The evidence
In a study of more than 122,000 adults who had treadmill tests at the Cleveland Clinic, published in JAMA Network Open in 2018, higher fitness was associated with lower mortality across every age group, with no upper limit to the benefit. People in the lowest fitness group had roughly five times the risk of death during follow-up compared with those in the elite group. The authors noted that the risk tied to low fitness was comparable to or greater than that of traditional risk factors such as smoking, diabetes and coronary artery disease.
This is observational research, so fitness may partly reflect underlying health. But trials consistently show that exercise training raises VO2 max, and the size and consistency of the association across studies is striking.
Where the biggest gains are
The largest drop in risk comes from moving out of the least-fit group. You do not need to become an athlete to benefit. For someone who is currently sedentary, the first few months of regular aerobic exercise deliver the most.
How to measure it
The gold standard is a lab test with a mask that measures oxygen use during a graded treadmill or bike test, offered by many sports medicine clinics and longevity practices. Smartwatches estimate VO2 max from heart rate and pace; they are useful for tracking trends over time but can be off for any individual reading.
How to raise it
Current U.S. guidelines recommend 150 to 300 minutes a week of moderate activity or 75 to 150 minutes of vigorous activity, plus muscle-strengthening work at least two days a week. A practical structure:
- Most of your cardio at a steady, conversational pace (often called “zone 2”). This builds an aerobic base and is easy to recover from. Its popularity rests more on physiology and athlete experience than on long-term outcome trials, but it is a sound foundation.
- One or two weekly sessions of harder intervals. A classic format is four rounds of four minutes hard, with three minutes easy between. Interval training is among the most effective ways to raise VO2 max in studies.
- Consistency over months. Fitness responds within weeks and keeps improving with steady training.
Exercise also has well-documented effects on mood; see our report on exercise as a treatment for depression. If you have heart disease, chest pain or haven’t exercised in years, check with your clinician before starting high-intensity work.
Frequently asked questions
What is a good VO2 max?
It depends heavily on age and sex. Being above average for your age group is associated with lower mortality, and moving out of the lowest group gives the largest benefit.
Are smartwatch VO2 max readings accurate?
They are estimates. They are best for tracking your own trend over time rather than as an exact number.
Is zone 2 training enough to improve VO2 max?
Steady aerobic training helps, especially for beginners, but adding some higher-intensity intervals is generally more effective at raising VO2 max.