CUPERTINO, Calif.—During the keynote presentation kickoff of its annual Worldwide Developers Conference, Apple revealed the first details about the next major software update for the Apple Watch: watchOS 9.

The forthcoming OS makes a big push in health and fitness, adding a bevy of new features for both. On the Fitness front, Apple is expanding workout metrics to include heart rate zones, as well as some running-specific data. The Running activity mode will calculate vertical oscillation, stride length, ground contact time, and power (in watts), which you can see at a glance on your Apple Watch. Users will also be able to race against previous times on frequent routes, aided by voice alerts for pacing. All activity modes will add heart rate zone data, as well. If you set an HR zone for your workout, you’ll receive alerts indicating whether you’re in or out of that zone.

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  The new Multisport activity mode automatically changes from running, to cycling, to swimming.

Apple’s also adding a custom workout activity where the user can structure their own workouts with “work” and “recovery” intervals. Users will be able to set goals for pace, power, heart rate, and cadence, as well as heart rate zones. Alerts via haptic feedback and voice keep you updated on these metrics and tell you when to switch from each stage. For triathletes, the new Multisport activity tracking mode will switch from swimming, cycling, and running automatically.