Oura's new Cardio Effort score tells you when to ease off, not just push harder

The skim

• Oura is adding Cardio Effort, a weekly measure of how hard your workouts pushed your heart compared with your own baseline.
• A new automatic VO2 Max estimate, in Oura Labs, replaces the old six-minute walking test with data from your regular GPS walks, runs and hikes.
• Both need a Gen3 ring or newer and an active membership, and both roll out gradually.

Cardio Effort: how hard was that, really?

Most fitness trackers tell you what you did: steps, distance, calories. Oura's new Cardio Effort feature tries to answer a different question: how much strain did that put on your cardiovascular system? It combines heart-rate intensity with duration, so a short interval session and a long easy walk can end up with similar scores. Oura says it's built on an established exercise-science approach called Training Impulse (TRIMP).

Each workout adds to a weekly total that resets at the start of every week. Oura then places your week in one of five personalized bands, from Light to Reaching, based on a rolling six-week window of your own history rather than population averages. Oura says the middle "Maintaining" band is a perfectly good target. When you land in "Reaching," the app nudges you to consider recovery instead of pushing harder, which is unusual for a fitness app.

According to Oura's support page, the app needs about two weeks of data before your first score. After that, it shows up on the post-workout screen, as a card on the Today tab and in a weekly graph. Strength training, yoga, cycling and other recorded workouts count. If heart-rate data is patchy, which happens with gripping activities like weightlifting, you get an estimated value instead.

VO2 Max without the walking test

Oura previously estimated VO2 Max, a common gauge of aerobic fitness, through a dedicated walking test. The new automatic version, formerly called Cardio Capacity, runs in the background using your GPS-tracked outdoor walks, runs and hikes. Per Oura's Labs documentation, you need at least 30 days of ring data and five qualifying workouts before you get a first score. After that, it updates as you log more activity and shows a fitness category and long-term trend. You can still add a lab result manually, but it won't overwrite Oura's estimate.

Why it matters

Smart rings and watches are racing to turn raw sensor data into advice people can use. Cardio Effort is Oura's answer to the strain and training-load scores rivals already offer, with one notable difference: it frames "enough" as personal and treats rest as a feature, not a failure. Automatic VO2 Max removes a chore that most people probably skipped. As with any wearable estimate, it's best read as a trend over months, not a lab-grade number.