Apple Watch wearers have learned that the Watch OS eventually stops checking for heart rate in 10-minute intervals, but that irregularity of the health checks' cadences is all intentional, Apple says.
The irregular heart rate tracking appeared with the update to Watch OS version 1.0.1 and, for a while, was thought to be a bug. Apple updated its support site's documentation on Heart Rate Glance to make clear that seemingly sporadic heart rate checks aren't random or a product of a bug.
"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," says Apple.
While motion delays Heart Rate Glance's checks for beats per minute (BPM), Watch wearers can still manually check their heart rate. The Workout app will still monitor wearers' heart rates as they engage in physical activity.
With the ability to check heart rate manually and the Workout App doing so automatically, there has been speculation that Apple's decision to relax the monitoring was a move that seeks to conserve battery life.
A more likely motive may be Apple's desire to free up processing power, so that the regular heart rate checks don't interfere with any other software that wearers may be using. As App Advice points out, the Watch's ability to accurately track a wearer's heart rate may be hindered by arm movement.
"Even under ideal conditions, Apple Watch may not be able to get a reliable heart rate reading every time for everybody," says Apple. "Motion is another factor that can affect the heart rate sensor. Rhythmic movements, such as running or cycling, give better results compared to irregular movements, like tennis or boxing."
While it's good news to know the irregular heartbeat checks aren't a bug, even better news may be the improved support for third-party apps. Apple is expected to give developers a better idea as to when the WatchKit platform will open in full.
The announcement is expected to come during Apple's annual Worldwide Developers Conference (WWDC), which starts on June 8. Full access to the Watch Kit application programming interface will enable developers to create apps that run natively on the Watch.
Right now, third-party apps are side loaded onto Watches and it's up to iPhones to handle the processing. The current setup has resulted in third-party apps being notably slower than Apple's native Watch software, but that will change soon.
