The Apple Watch comes with several health-tracking features, and a relatively lesser-known one is the ability to measure a user’s Cardio Fitness. This feature should not be confused with the Apple Watch’s other heart health monitoring abilities, such as sending notifications when a user’s heart rate is too high or low, or irregular rhythm notifications that can detect instances of atrial fibrillation (Afib). Certain Apple Watch models also have the ability to record the wearer’s ECG via the electrical heart sensor built into the digital crown.
With watchOS 7, Apple introduced the ability to track V02 Max levels on the Apple Watch Series 3 and above. V02 Max estimates cardiorespiratory fitness levels by measuring the user’s heart rate response to physical activity. On the Apple Watch, V02 Max is called ‘Cardio Fitness’ which is why users might not be aware the feature exists. Apple says that enabling measurements for Cardio Fitness can provide a strong indicator of a user’s overall health and even predict their long-term health.
Related: Apple Watch: How To Set Up Heart Health Notifications
To set up Cardio Fitness and enable notifications, users will need to ensure their Apple Watch (Series 3 or above) is updated to the latest version of watchOS, and their iPhone is updated to the latest version of iOS. On an iPhone, open the Health app and tap on the Browse tab at the bottom. Then tap on Heart, followed by Cardio Fitness. Tap on Set Up and Next to confirm health details such as age, sex, height, weight, and medications that can affect heart rate. Tap on Next again to learn about factors that can lower Cardio Fitness levels, such as age, pregnancy, and some lung and heart conditions. Tap on Turn On Notifications to receive notifications if detected Cardio Fitness levels are low. Apple notes that users need to be at least 20 years of age to enable this feature. Tap on Done to complete the setup. The Apple Watch will now send users a notification if it detects low Cardio Fitness levels. If the levels continue to remain low, additional notifications will be sent every four months.
Cardio Fitness Data At A Glance
Once Cardio Fitness has been set up, users can view the recorded data on their iPhone. To do this, open the Health app and tap on the Browse tab. Tap on Heart and then Cardio Fitness. From the tabs at the top, tap on D, W, M, or Y to view the average levels for a day, week, month, or year. Alternatively, tap on Show All Cardio Fitness Levels to see all the recorded data in the app. Tap on any recorded Cardio Fitness level to compare results to other levels based on age and sex. Apple notes that if users find their Cardio Fitness is low, they can improve their V02 Max levels by increasing the frequency and intensity of cardio workouts.
On the Apple Watch, V02 Max levels aren’t measured by a specific sensor. Instead, the Watch uses a combination of heart and motion sensors to estimate Cardio Fitness levels during an outdoor walk, run or hike that’s started via the Workout app. Apple notes that the activity needs to be performed on relatively flat ground, and there should be adequate GPS signal, heart rate signal quality, and exertion for a valid measurement. Users need to be wearing the Apple Watch for at least 24 hours and have worked out several times before they can receive an initial estimate of Cardio Fitness levels.