PX7 Training · Articles

Research · 3 min read · 2026-10-12

Can you trust your watch's VO₂max?

A review of 14 studies found watch estimates close on average, but often up to about 10 ml/kg/min off for the individual runner.

Many running watches give you a VO₂max number, and it is tempting to follow it closely. A review of the research shows how close those numbers get to a real lab test, and where they fall short.

What the researchers did

An international network of researchers, INTERLIVE, collected 14 studies that compared VO₂max estimated by consumer wearables with VO₂max measured in a lab. They pooled the results and looked at how far off the watches were, both on average and for the individual person.

What they found

The method mattered. Devices that estimate VO₂max from resting data overestimated it by about 2 ml/kg/min on average, and for an individual the error could be much larger.

Devices that use data from exercise, such as heart rate and speed during a run, were right on average. For the individual, though, the estimate could still be up to about 10 ml/kg/min too high or too low. If your watch says 50, your real value could be somewhere around 40 or 60.

What it means for you

Use the number as a trend, not as a measurement. Compare it over months, with the same watch, and mostly from similar runs. Don't compare it with friends who use another brand, and don't change your training because the number moved by one or two points.

A race or a well-run test says more about your current fitness than a watch estimate.

What the study can't tell you

The review covers the devices and algorithms that had been tested by then. Newer models may do better or worse. The researchers also called for better and more consistent testing of these features.

How we use it

PX7 Training sets your targets from your races, tests and runs, not from the watch's VO₂max. A higher number on your watch does not on its own make your training harder.

Source

Written by Jørgen Larsen for PX7 Training.