Upgrading to Watch OS 1.0.1 decreases the frequency of heart rate readings taken by the Apple Watch when users are in motion, according to the device’s updated heart monitoring support document. “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,” according to the site. Watch OS 1.0 recorded a user’s heart rate every 10 minutes, regardless of whether a user’s arm was in motion. The change only applies to passive heart rate monitoring, which uses infrared sensors to determine heart rate. Users can still record more frequent heart rate measurements by starting a workout in the Workout app — which uses green LED lights and photo sensors to collect heart rate data — and can still get readings at any specific time using the Heart Rate sensor. [via 9to5Mac]