The Apple Watch Series 12 is the start of a new wearable era

Apple's latest generation of smartwatches, the Apple Watch Series 12 and Ultra 4, have introduced a new feature called the Readiness score. This metric determines whether you are in optimal shape to handle a physically or mentally demanding day based on a variety of watch data. The Readiness score is accompanied by a simple prompt to put it into context.

However, this is not a new development for other wearable owners, as devices like the Oura Ring, Garmin watch, Whoop, and Google Fitbit Air already provide a readiness score of some kind.

Craig Bolton, Director of Fitness Technologies at Apple, explained that the advancements in hardware technology made it the right time to introduce the Readiness score. The Health Sensing System in the new watches allows for continuous heart rate variability and all-day heart rate measurements, which are crucial for providing accurate and concise Readiness scores.

The Readiness score can be viewed through the dedicated Readiness Watch app, Watch complication, and the redesigned Health app. It takes into account your sleep score, vitals data like temperature and blood oxygen, recent workout data, and training load. To see scores, you need to record seven nights' worth of sleep data to establish a baseline. Apple chose to score users on a scale of 1-10, rather than 1-100, to keep the feature simple and intuitive.

The accuracy of the Readiness score is strongly tied to Apple's ability to continuously monitor heart rate with a higher sampling frequency, thanks to the new Health Sensing System. The Series 12 and Ultra 4 can monitor heart rate every five seconds, while the Apple Watch Series 11 can only do so every five minutes. Heart rate variability (HRV) is also a critical metric in determining Readiness scores, with two HRV measurements introduced: overall HRV and recovery HRV.

Recovery HRV is particularly relevant for Readiness scores and can be viewed within the Heart app on the Watch.

Apple's Readiness score is rooted in research conducted by the company, including the Heart Rate and Movement study and the Heart Rate Accuracy study. These studies helped "tune the experience" of the Readiness scores. Additionally, Apple conducted other studies to understand users' fatigue levels and how their metrics align with their perceived well-being.