Apple has altered the way it measures cardio-vascular fitness in its Health app as part of iOS 26. Its new calculation uses data directly from the Apple Watch. If you’re running a beta of iOS 26 look at the data in the Health app, you will see a message offering you the opportunity to use what Apple says is a more accurate measurement of VO2 Max – a metric that indicates your level of cardio-vascular fitness.
If you choose to accept this change (it’s irreversible) it’s likely you will see your current and historical VO2 Max data change. For some, this results in an increase while others are seeing a decrease in Apple’s estimate of VO2 Max.
While this might either be an ego boost or gut punch it is important to realise that Apple’s VO2 Max estimate is just that – an estimate. It uses data such as heart rate, age, weight, height and biological sex to estimate how well your body is using oxygen while you exercise. The only way to accurately assess VO2 Max is in a lab where the amount of oxygen you inhale and exhale, your heart rate and workload are precisely measured.
Apple does provide some information on how it derives VO2 Max. It seems that what Apple has done is to tweak things to get, what it says is, a more accurate result.
My advice is to not focus too much on the value Apple ascribes to your VO2 Max but to focus on the trend. If the graph Apple presents in the Health app shows a decline, then it might be time to increase the amount of aerobic activity you do.
Anthony is the founder of Australian Apple News. He is a long-time Apple user and former editor of Australian Macworld. He has contributed to many technology magazines and newspapers as well as appearing regularly on radio and occasionally on TV.