I’m pretty excited about this news https://www.apple.com/newsroom/2020/12/cardio-fitness-notifications-are-available-today-on-apple-watch/
Now, with watchOS 7, Apple Watch uses multiple sensors, including the optical heart sensor, GPS, and the accelerometer, to estimate lower levels, too. This is significant because direct measurement of VO2 max typically requires a rigorous clinical test with specialized equipment that is not readily accessible to most people. watchOS 7 also allows Apple Watch to take cardio fitness measurements as users walk throughout the day, whether or not they are tracking a workout. With this innovation, Apple Watch is better able to measure VO2 max for users with low cardio fitness, who may not complete high-intensity workouts.
Today iOS 14.3 and watchOS 7.2 enable Apple Watch users to visit the Cardio Fitness category in the Health app on iPhone to review whether their cardio fitness level is classified as high, above average, below average, or low, relative to people in their same age group and of the same sex, according to data from the Fitness Registry and Importance of Exercise National Database (FRIEND). They can also see how their cardio fitness level has changed over the past week, month, or year. If a user’s level falls within the low range, they can receive a notification on Apple Watch, along with guidance on improving it over time and having a conversation with their doctor.
Since I’ve been working from home, I’m guessing that my fitness is low during the weekends and high on the weekend.