Your watch gives you a VO₂ max score. Social media tells you it's one of the most important numbers for longevity.

But what does it actually mean?

In this episode of The Fundamentals of Fitness, Alison breaks down the science of VO₂ max without turning it into another number you need to obsess over.

We explore what VO₂ max actually measures, how your heart, blood vessels and muscles work together to use oxygen, why cardiorespiratory fitness is associated with long-term health outcomes, and how accurate your smartwatch estimate really is.

Then we get practical.

Zone 2 or HIIT? Do you need to run? How hard should cardio actually feel? And what's the best way to know whether you're getting fitter?

Because VO₂ max can be useful information.

But it's not your biological expiry date. ...