Since Apple Watch gets a hardware update like clockwork every fall, it’s a safe bet we’ll see a Series 7 model next month alongside the iPhone 13. There are plenty of rumors about what to expect, including a better display and a new flat-edged design, both of which sound great to me.

But I’m less keen on the prospect that Apple Watch Series 7 might come with additional health sensors. Here’s why.

Apple’s VO₂ max metric measures the performance of your heart and lungs when you push yourself to the limit. Up until now, though, it’s only been useful to serious fitness fanatics. No wonder Apple buried it in the Health app, where most users never found it.

But watchOS 7.2 and iOS 14.3, which Apple released Monday, change all that. In those updates, the VO₂ max metric has been renamed Cardio Fitness. Now it can detect lower ranges and send alerts when the reading gets too low. That makes it the latest in a series of potentially life-saving health notifications from Apple Watch.

Here’s everything you need to know to get the benefit of this essential new feature.