VO2 Max: What It Is, Good Values by Age and How to Increase It

VO2 max is the maximum amount of oxygen your body can take in and use during all-out exercise, expressed in milliliters per kilogram of body weight per minute (ml/kg/min). It's the best single measure of cardiorespiratory fitness, and higher values are strongly associated with longer life. You can raise it at any age with a mix of easy aerobic training and 1 to 2 interval sessions a week.

Smartwatches now estimate VO2 max for millions of people, so the number is suddenly everywhere. Here's what it means, what's "good", why it matters for health, and exactly how to improve it.

Why VO2 max matters for health

• Kodama and colleagues (2009), in a meta-analysis in JAMA, found that each 1-MET increase in cardiorespiratory fitness (1 MET = 3.5 ml/kg/min of VO2) was associated with about 13 percent lower risk of death from any cause and 15 percent lower risk of cardiovascular events.
• Mandsager and colleagues (2018) followed 122,007 patients who did treadmill tests. Low fitness was associated with a mortality risk comparable to, or greater than, traditional risk factors like smoking and diabetes, and the highest-fitness group had the lowest risk, with no upper limit of benefit observed.

These are associations, not guarantees, but they're among the most consistent findings in exercise science.

What is a good VO2 max?

The best US reference comes from the FRIEND registry (Kaminsky and colleagues, 2015): 7,783 maximal treadmill tests with gas analysis in healthy adults aged 20 to 79. Key numbers:

So a simple way to read your number: being above the median for your age and sex is "good", and the higher above it, the better. A 50-year-old with the VO2 max of a typical 40-year-old is, in fitness terms, about a decade younger.

Watches and fitness apps use their own reference tables, which often differ from FRIEND. Compare yourself with yourself over time rather than chasing a category label.

How is VO2 max measured?

Watch tip: estimates are most reliable when you run or walk outdoors on flat ground with accurate max heart rate settings.

How to increase your VO2 max

1. Build an aerobic base. Most of your cardio at an easy, conversational pace (zone 2; see heart rate zones). Aim for 150+ minutes a week.
2. Add intervals. A 2015 meta-analysis by Milanović and colleagues found high-intensity interval training improved VO2 max more than continuous endurance training in healthy adults.
3. Lose excess body fat. VO2 max is expressed per kg, so the number rises when weight falls (see calorie deficit).
4. Be consistent for months. Untrained people can see meaningful improvements within 8 to 12 weeks; gains slow with experience.

12-week VO2 max plan

Use running, cycling, rowing, swimming, incline walking or a mix. Retest at week 12 with the same method. More interval formats: HIIT workout.

VO2 max and age

VO2 max declines with age, partly because max heart rate falls and partly because people move less. Training slows the decline considerably. For older adults, start with walking and cycling, add gentle intervals, and include strength training to keep muscles that use oxygen: see strength training for seniors.

Safety

Interval training is safe for most healthy people, but check with a doctor before hard intervals if you have heart disease, high blood pressure, diabetes, are over 50 and inactive, or have symptoms like chest pain or fainting.

Next steps

Runners: 10k training plan and half marathon training plan both build VO2 max. For a 12-week plan combining cardio and strength with tests and a log, see our programme.

Frequently asked questions

Can you increase VO2 max after 50?

Yes. Older adults improve VO2 max with consistent aerobic training and intervals. The gains may be somewhat slower, but fitness differences between active and inactive people of the same age are large.

How fast can VO2 max improve?

Untrained people often see noticeable improvements within 8 to 12 weeks. Trained athletes improve more slowly.

Is my Apple Watch or Garmin VO2 max accurate?

Watch estimates can be off by several points compared with lab tests, but they're useful for tracking trends over time if you use them consistently.

Does losing weight increase VO2 max?

Since VO2 max is expressed per kilogram of body weight, losing fat increases the number even if your absolute oxygen uptake stays the same.

What is the best exercise to improve VO2 max?

Intervals at high intensity (such as 4 x 4 minutes hard) combined with plenty of easy aerobic exercise. Running, cycling, rowing and swimming all work.

Does genetics affect VO2 max?

Yes, genetics influences both starting VO2 max and how much it responds to training. But nearly everyone improves with consistent training.

Studies cited

• Kodama S et al. (2009). Cardiorespiratory Fitness as a Quantitative Predictor of All-Cause Mortality and Cardiovascular Events in Healthy Men and Women: A Meta-analysis. JAMA. doi:10.1001/jama.2009.681
• Mandsager K et al. (2018). Association of Cardiorespiratory Fitness With Long-term Mortality Among Adults Undergoing Exercise Treadmill Testing. JAMA Network Open. doi:10.1001/jamanetworkopen.2018.3605
• Kaminsky LA, Arena R, Myers J (2015). Reference Standards for Cardiorespiratory Fitness Measured With Cardiopulmonary Exercise Testing: Data From the Fitness Registry and the Importance of Exercise National Database. Mayo Clinic Proceedings. doi:10.1016/j.mayocp.2015.07.026
• Milanović Z, Sporiš G, Weston M (2015). Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials. Sports Medicine. doi:10.1007/s40279-015-0365-0