Compared to past World Wide Developer Conferences, Apple's latest presentation was light on health-related content. But buried in the talk about streaming music and HomeKit were some significant updates to both Apple Health and HealthKit as well as the fitness and health features of the Apple Watch.

Early in the presentation, Craig Federighi, Apple's Senior VP of Software Development announced that Apple's data exchange, HealthKit, would add several new fields: hydration, UV exposure, sitting time, and reproductive health. That last one finally addresses a rather galling omission of the platform that received a fair amount of criticism in the media when HealthKit was first announced. For details on what metrics, exactly, will be tracked in terms of menstruation, fertility, or ovulation, we'll likely have to wait until the update goes live. It's also worth noting that a number of fertility tracking apps, including Clue and Ovia, already integrate with HealthKit using the temperature field. A screenshot of some of the new HealthKit fields appearing in Apple's Health app is featured on the company's website.

Hydration is also noteworthy insofar as it's been a surprisingly popular thing for third-party Apple Watch apps to track: A MobiHealthNews analysis found 12 distinct hydration tracking apps on the first day of the Apple Watch launch. Sedentary time, of course, is already one of the three tracking rings on the Apple Watch's fitness app. 

Later in the show, VP of technology Kevin Lynch shared a number of new health and fitness features that will come to the Apple Watch when the second version of its operating system launches. A number of fitness apps will be able to run natively on the watch, Lynch said, allowing third party apps to contribute to the activity ring on the Apple Watch's fitness app.

"We’re also enabling Siri to start workouts so you can just raise your wrist and say 'Hey Siri, start a thirty-minute run in the park' and it will start the workout app and get it going for you," Lynch said. "You can also say things like 'Go for a 300 calorie bike ride', or 'Go for a five mile run'. And it will just start the workout without you having to touch the watch at all."

Lynch also announced that Apple Watch wearers will be able to view HealthKit data right from their watch face, including streaming heart rate data.