Check Your Heart Sensor Settings
The Apple Watch’s movement and workout data will be much more accurate when the device is actively taking your heart rate. But there are several settings that can affect whether or not your Apple Watch is regularly taking heart rate measurements.
- For example, the Apple Watch won’t track your background heart rate if Wrist Detection is disabled.
- Power Saving Mode also turns off the heart rate sensor.
Apple also notes that rhythmic movements like running or biking, typically result in more accurate heart rate readings than activities like tennis or boxing.