VO2 max by age: what's a good Cardio Fitness level?
VO2 max is how much oxygen your body can use during hard exercise, measured in mL per kg per minute. Apple Watch estimates it and calls it Cardio Fitness. Here's how to tell whether your number is low, average or high for your age.
Reference levels (men)
Middle 50% of people = between the 25th and 75th percentile. Treadmill-measured VO2 max from the FRIEND registry.
| Age | 25th percentile | Median (50th) | 75th percentile |
|---|---|---|---|
| 20–29 | 40.1 | 48.0 | 55.2 |
| 30–39 | 35.9 | 42.4 | 49.2 |
| 40–49 | 31.9 | 37.8 | 45.0 |
| 50–59 | 27.1 | 32.6 | 39.7 |
| 60–69 | 23.7 | 28.2 | 34.5 |
| 70–79 | 20.4 | 24.4 | 30.4 |
Reference levels (women)
| Age | 25th percentile | Median (50th) | 75th percentile |
|---|---|---|---|
| 20–29 | 30.5 | 37.6 | 44.7 |
| 30–39 | 25.3 | 30.2 | 36.1 |
| 40–49 | 22.1 | 26.7 | 32.4 |
| 50–59 | 19.9 | 23.4 | 27.6 |
| 60–69 | 17.2 | 20.0 | 23.8 |
| 70–79 | 15.6 | 18.3 | 20.8 |
Source: Kaminsky LA, Arena R, Myers J. Reference standards for cardiorespiratory fitness measured with cardiopulmonary exercise testing: data from the Fitness Registry and the Importance of Exercise National Database (FRIEND). Mayo Clinic Proceedings, 2015 (PubMed).
The five levels
A large study of 122,007 adults (Mandsager et al., JAMA Network Open, 2018) grouped people by fitness for their age and sex:
- Low: below the 25th percentile
- Below average: 25th to 49th
- Above average: 50th to 74th
- High: 75th to 97.6th
- Elite: 97.7th and up (about 2 standard deviations above average)
In that study, each step up in fitness was associated with lower all-cause mortality, and they didn't find an upper limit to the benefit. It's an association from observational data, not a guarantee, but it's one reason VO2 max gets so much attention in longevity circles.
About the Apple Watch number
- Apple estimates Cardio Fitness during outdoor walks, runs and hikes with GPS, usually 20+ minutes with your heart rate up. Indoor workouts, cycling and strength training don't update it.
- It's an estimate. Treat the trend over months as more meaningful than any single reading.
- Check it in the Health app → Heart → Cardio Fitness.
How to raise it
Regular aerobic training, and plenty of it, is the foundation. Most programs combine a lot of easy Zone 2 work with a little hard interval work, such as one session of intervals a week. Consistency over months matters more than any single workout.
Check with your doctor before starting hard exercise, especially if you have a heart condition. General fitness information, not medical advice.
Zone 2 Training Coach shows your Cardio Fitness level from your Apple Watch, and what it takes to reach the next one.
