WatchOS 9 will know what heart rate zones youre in during sleep and workouts

As expected, Apple has introduced watchOS 9 at WWDC. The new Apple Watch platform includes a big upgrade to fitness features with enhanced metrics that include distance and time intervals. You'll know when to slow down for a recovery, for instance. There are also heart rate zones (for both sleep and workouts), multi-sport workouts and personal bests that can help you improve performance over time. You won't always need the wristwear, though— Apple has also promised to offer fitness features on the iPhone.

Fitness+ is more useful, too, with on-screen guidance to help you tackle all-out pushes and recoveries in several workout types. You'll also find support for AirPlay to devices besides the Apple TV.

A new Medications feature in Health on the Apple Watch and iPhone helps you manage notifications, and will give you alerts when it's time for your next dose. You can even learn about potentially harmful drug interactions. If you're taking care of a loved one, they can also volunteer to share their health information with you. Atrial fibrillation tracking, meanwhile, now provides a history to let you know often your heart stays in an irregular rhythm.

You'll also see some interface tweaks such as banner notifications, a priority-focused dock, a redesigned Calendar app, double-pinch "Quick Actions" gestures and a new Siri presentation. Apple has both revamped existing watch faces (such as Astronomy, Simple and Utility) and introduced new ones like Lunar, Metropolitan and Playtime.

The developer beta of watchOS 9 is available today, with a public beta expected in July. The finished update will arrive this fall for anyone using an Apple Watch Series 4 or later. This is the swan song for Apple's original smartwatch form factor, in other words — you may want to think twice about buying the Series 3 (still on sale) knowing that it won't get major updates from here on out.

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