Following user concerns regarding a change in heart rate measurements after the first Watch OS update, Apple Watch support documents now back the change as intentional, and likely here to stay for the near future.

With Watch OS 1.0.0, Apple Watch took heart rate measurements every 10 minutes, storing those measurements in the Health app. After users updated to Watch OS 1.0.1, many noticed a significant decline in the number of measurements taken per day. Most people wrote this off as an accident that would be fixed in the next update, but Apple’s support documents have been modified, claiming otherwise. The updated paragraph reads as follows:

You can check your heart rate any time using the Heart Rate Glance. And when you’re using the Workout app, Apple Watch measures your heart rate continuously during the workout. This information, as well as other data it collects, helps Apple Watch estimate how many calories you’ve burned. In addition, Apple Watch attempts to measure your heart rate every 10 minutes, but won’t record it when you’re in motion or your arm is moving. Apple Watch stores all your heart rate measurements in the Health app.

Many had suspected that the sporadic intervals between measurements in Watch OS 1.0.1 were the result of a bug that would be fixed in a later update. Instead, Apple seems to be repurposing the heart rate monitor for resting heart rate when not using the Workout app. An argument could be made that the Workout app could be used for other periods of time, but the move seems like a backtrack in comparison to the original, more convenient, 10 minute measurement intervals.

As someone who experienced using Watch OS 1.0.0, I can say that it was very convenient to see a record of my heart rate at 10 minute intervals. The measurements seemed pretty accurate on average, with the exception of a few obvious outliers (one measurement of about 43 bpm in a block of measurements around 70 bpm). I suspect that these outliers are the reason for Apple’s decision to make the change.

On the bright side, this move shows that Apple takes accuracy seriously with the heart rate monitor. For those relying on Apple Watch to monitor a medical condition, outliers like I experienced could be taken seriously and cause false alarm. If Apple is able to iron out the kinks, future Watch OS updates will probably include more frequent and accurate active heart rate measurements. For now, users can measure their heart rates on demand via the Heartbeat glance, or Workout app.

Source: Apple via 9to5Mac