Your smartwatch already estimates VO₂ max, one of the best longevity markers. How accurate it is, how to read the number, and how to actually improve it.
Here is a longevity tip that costs nothing extra: the watch on your wrist probably already estimates your VO₂ max, one of the strongest predictors of how long you will live. Most people never look at it. Here is how to find it, how much to trust it, and how to actually move the number.
Your watch already measures it
Modern smartwatches, Apple Watch, Garmin, Polar, Samsung, COROS, Suunto and others, estimate VO₂ max automatically from your heart rate and movement during walks, runs and other activities. On Apple Watch it appears as “Cardio Fitness”; on Garmin and others it is listed directly as VO₂ max. No chest strap or lab required.
Why care? Because VO₂ max is genuinely predictive of longevity, see VO₂ max and lifespan, and having it tracked passively, for free, is a gift most people ignore.
How accurate is it, really?
Wrist-based VO₂ max is not a laboratory replacement, but it is good enough to be useful. Validation studies put reputable devices within roughly 3 to 8 percent of lab measurement. The absolute figure may be a touch high or low, but what matters for longevity is the trend: is your number holding or climbing over months? For that, your watch is reliable.
Getting the most accurate reading
To sharpen the estimate:
- Fit matters: wear the watch snugly, one finger-width above the wrist bone.
- Enter accurate profile data, age, weight and especially resting heart rate, which the calculation leans on.
- Feed it good data: regular brisk outdoor walks or runs give the algorithm clean heart-rate and pace signals. Treadmill and indoor sessions can be less accurate on some devices.
- Be patient: estimates settle and improve over a few weeks of consistent wear.
For a broader look at devices, see best wearables for longevity.
The part that counts: improving it
Tracking is pointless without training. To raise your VO₂ max:
- Build a Zone 2 aerobic base several times a week.
- Add one hard interval session, such as the Norwegian 4x4.
- Stay consistent, VO₂ max is trainable at any age.
Watch the number climb over the following weeks, it is one of the most motivating feedback loops in fitness. Estimate yours with our VO₂ max tool to get a starting point. And if you want the number to actually rise, our exercise-led home-visit coaching across KL and Selangor measures your baseline, builds the Zone 2 and interval work around it, and re-tests at 12 weeks, one WhatsApp message starts it.