Apple Watch’s new heart rate features won’t work on the original Watch model

Apple’s new Apple Watch software, WatchOS 4, includes several updates to the health and fitness tracking features of the Watch, the most interesting of which are new heart rate monitoring features. With the new software, the Watch will show resting heart rate, walking heart rate, and recovery rate, and flag abnormal spikes even when wearers aren’t working out.

But it turns out that not all Apple Watch users will experience those. As pointed out both in 9to5Mac’s WatchOS 4 writeup and by users on Twitter earlier today, the new heart rate monitoring features are limited to Series 1, Series 2, and brand-new Series 3 smartwatches. The original Apple Watch, the very first one that launched in 2015, won’t support some of the new heart rate features in WatchOS 4.

There are technical reasons for this. The Series 1, 2, and 3 have faster chips and larger batteries than the original smartwatch. (The original watch is not the Series 1; the Series 1 was launched at the same time as Series 2 in 2016, and got a processor bump.)

Reviews of the new Apple Watch Series 3 published yesterday, including our own review, which revealed a bug in the way the new, LTE-equipped Watch tries to connect to WiFi networks when the Watch is away from the phone. While the Watch’s connectivity has been problematic, I gave the new WatchOS 4 software “two thumbs up” for its slightly redesigned UI and the new health-tracking features.

But not all Apple Watch wearers will get to experience the full extent of the latter. Our review has been updated to include this detail.