What Oura launched
Oura announced both features in "Cardio Effort and Automatic VO2 Max" on 20 October 2026.
- Automatic VO2 max replaces the feature formerly called Cardio Capacity, which needed a dedicated six-minute walking test. It is in Oura Labs, Oura's section for experimental features, for Oura Ring Gen3 and later. The first estimate appears after five qualifying GPS-enabled walks, runs or hikes and is shown in ml/kg/min with a category of Low, Fair, High or Peak and a trend over time.
- Cardio Effort scores each workout by its intensity and duration, using your heart-rate response when available. It is built on the Training Impulse (TRIMP) method, and each workout adds to a weekly total that resets at the start of each week.
- The weekly total lands in one of five bands relative to your personalised range: Light, Fair, Maintaining, Building or Reaching. The range uses a rolling six-week window of your activity and appears after two weeks of use.
- Oura notes that VO2 max is a slow-moving metric and that no Cardio Effort range guarantees a change in VO2 max or Cardiovascular Age. Lab results or numbers from another device can be saved separately and do not overwrite Oura's estimate.
Why VO2 max matters for longevity
A Cleveland Clinic cohort of 122,007 patients referred for treadmill testing, followed for a median of 8.4 years, found risk-adjusted all-cause mortality fell as cardiorespiratory fitness rose, with no observed upper limit of benefit. Low fitness compared with elite fitness carried an adjusted hazard ratio of 5.04, comparable to or greater than smoking, diabetes or coronary artery disease in the same analysis (JAMA Network Open, 2018). Fitness in that study came from symptom-limited treadmill tests, a different method from a ring estimate.
How accurate is a wearable VO2 max?
A 2022 meta-analysis of 14 validation studies by the INTERLIVE network (Sports Medicine, 2022). Devices that estimate from exercise data were close on average, and the error for an individual was still large.
| Type of estimate | Average bias | Limits of agreement |
|---|---|---|
| From resting data | +2.17 ml/kg/min (overestimates) | −13.07 to +17.41 ml/kg/min |
| From exercise data (like GPS workouts) | −0.09 ml/kg/min | −9.92 to +9.74 ml/kg/min |
The authors concluded that exercise-based estimates work well at the population level, while the error for an individual is large and the methods still need improvement for sport or clinical use. Oura's new estimate is exercise-based. A single reading of 42 could sit several points away from a lab test; a change over months on the same ring and the same routes is more informative.
How to read your Oura VO2 max and Cardio Effort
- Treat the first estimate as a starting point. It needs five qualifying GPS workouts, and further activities refresh it over time.
- Compare yourself only with yourself, on the same device. Numbers from a watch, a ring and a lab test come from different methods.
- Judge the estimate over months. Oura itself describes VO2 max as slow-moving.
- Use Cardio Effort to plan the week: Maintaining is a valid goal, and Oura says repeated Reaching weeks may be a cue to prioritise recovery.
- Check recovery next to load. High Cardio Effort workouts can temporarily lower HRV, so read resting heart rate and HRV after high-load weeks. Our guide on training load and resting heart rate shows what to look for.
- If you want to raise fitness, test one plan for several weeks, such as the Zone 2 base-building experiment, and judge it on the trend.
Our VO2 max guide covers the physiology and reference ranges. For chest pain, unusual breathlessness or a heart condition, talk to a doctor before raising training load.
Put your VO2 max trend next to sleep and recovery
Longvai connects Oura, WHOOP, Garmin and Apple Health or a CSV upload and reads each metric against your own baseline. Pro adds a long-horizon VO2 max trend forecast and the Experiment Tracker for 2–6 week n=1 trials.
FAQ
How does Oura estimate VO2 max now?
Since 20 October 2026, automatic VO2 max in Oura Labs (Gen3 and later) estimates it from regular GPS-enabled walks, runs and hikes. The first estimate appears after five qualifying activities.
Is Oura VO2 max accurate?
We found no independent validation study of the new Oura estimate in PubMed as of 9 November 2026. Across 14 studies of other wearables, exercise-based estimates were close on average but individual readings could differ from a lab test by about 10 ml/kg/min either way.
What is Cardio Effort?
A weekly total of cardiovascular load from your workouts, based on TRIMP, compared with your own six-week range in five bands from Light to Reaching.
Why does my VO2 max not change after each workout?
Oura describes VO2 max as a slow-moving fitness metric and focuses on meaningful changes over time rather than day-to-day variation.
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