Apple has created a new version 2 algorithm for the Apple Watch Series 4 and later to measure electrocardiogram (ECG) waves of one’s heart via the optical heart sensor.

The refreshed algorithm has been spotted in the upcoming iOS 14.3 and watchOS 7.2 updates, scheduled to release publicly before next Monday, December 14. The same algorithm powers the Apple Watch’s irregular heart rhythm detection that periodically measures your heart rate in the background and notifies you if it detects signs of atrial fibrillation.

As noted by MacRumors, the official documentation states that a new “version 2 algorithm” has been added, but no other information is included. “Based on beta code uncovered by MacRumors, it’s likely that the new algorithm will allow the ECG app to check for atrial fibrillation (AFib) at higher heart rates – during exercise, for example,” the write-up speculates.

iOS 14.3 and watchOS 7.2 are scheduled to release next Monday alongside the new Apple Fitness+ subscription service which requires these software updates. New in watchOS 7.2, a cardio fitness feature will ping you when your VO2Max levels drop below threshold, which might indicate possible issues with the user’s heart health and overall fitness.