The company is also said to be working on an improved ECG function that could properly deliver results in between 100 and 120 beats per minute.

There's no guarantee the new features will appear with the next generation of Apple Watch hardware, let alone through a software update. Apple hasn't been shy about wanting the Watch to serve as a vital health tool, however, and this could be more important than usual -- low blood oxygen levels can increase the risk of heart and lung attacks. Add rumors of further features, like sleep tracking, and it may be more a question of when Apple adds more health functions than "if."