Apple’s wearable, the Apple Watch , received its first update nearly two weeks ago, and already it has some explaining to do.
First noticed by 9to5Mac, the Apple Watch’s heart monitor, which is supposed to consistently record a user’s heart rate every 10 minutes, began to track data at longer and more irregular intervals after receiving the update.
Though it was initially perceived as a bug, Apple’s new support page, which specifically addresses the device’s heart rate features, says this is actually intentional. The company reports that the wearable will still attempt to track your heart rate every 10 minutes, but won’t record it if your arms are moving. Users can also still check their heart rates by manually checking its Heart Rate Glance feature, and the device will continue tracking heart rate during a workout.
The reason for this change remains unknown. Cutting down the sensor’s frequency may help to increase the device’s battery life, or improve the accuracy of its readings (which all wristband health trackers fall behind with when compared to an EKG machine). Unfortunately, Apple did not respond to a request for comment.