Everything You Need to Know About Apple’s HealthKit and How It Might Work with the iWatch

She’s watching herself become healthier right before her own eyes! (Thinkstock)

You may have heard about HealthKit, a detailed body-monitoring system that Apple debuted at its annual Worldwide Developers Conference this past June. Since the announcement, programmers have been tinkering away on the beta product, slowly adding to the long list of health stats that it’ll supposedly be able to track come Sept. 9.

From what we’ve seen so far, the HealthKit program that you and I will use, and that will likely be released alongside the iPhone’s new operating system, iOS 8,  will keep track of your vitals, emergency contacts, food intake, and other bodily failures/successes. Behind the app is a whole infrastructure for developers, and HealthKit data will be culled from several fitness apps and wearables. The Apple rumor mill also predicts that HealthKit will lay a foundation for the long-anticipated iWatch. Here’s what we know about how the two will work together.

Wait, back up. What’s HealthKit again?
HealthKit is one of those Apple-made staples (like the Clock or Camera app) that you’ll never be able to delete from your home screen. It’ll deliver a dashboard of data related to your health that you can view by day, week, month, or year. The system’s programmed alerts are meant to keep you within range of your health goals.

Within the kit is a folder called Health Data, which is the digital equivalent of the manila folder a doctor might glance at before visiting you in the exam room. This information is split into seven categories: Body Measurements, Fitness, Me, Nutrition, Results, Sleep, and Vitals. The subcategories within each range from basic information about your height or weight to “Number of Times Fallen,” whatever that means. Each of these subcategories is displayed in the form of a colorful flash card that you can display on your dashboard.

So, say you get plenty of deep sleep but aren’t the best exerciser. You can switch out one for the other, so the distance you’ve run over the past week is right there front and center, and you don’t have to be bothered with a stat you don’t care to be nagged about.

That’s personal information. Will anyone be able to see it?
At the moment, it doesn’t seem like Apple will forcefully integrate any social sharing features into HealthKit. However, a feature within the app called Medical ID allows you to enable something called Emergency Access.

It works like this: You enter basic health information like your birth date, blood type, medical conditions, allergies, medications, and other boring stuff. You can also include an emergency contact. Then, if something unexpected happens and you’re not conscious or alert enough to enter your phone’s access ID, bystanders can access this information from your lock screen. They’ll just need to tap Emergency, then Medical ID, and the Medical ID screen will pop up. Your rescuers will then be able to call any of the emergency contacts listed.

Public access to this information is concerning, yes, but ultimately you’ll have to decide between providing information that might save your life and withholding it to protect your privacy. Whatever you choose, it’s pretty easy to change your mind or edit the information.

Where will all the biometric health data come from?
Currently the only true hint of the information source is a folder within the Health app called Sources. This is where you’ll be able to pool the data coming from any fitness bands or monitoring gadgets you already have into HealthKit’s larger database. My Jawbone UP band, for instance, is able to track my sleep, steps, and daily food intake (if I remember to charge it, wear it, and enter my meals). It’s likely that fitness app developers, and those at activity-based companies, are rushing to have their own iOS 8–ready programs available soon after Apple’s Sept. 9 announcement.

Most fitness bands are equipped with tools (such as accelerometers) to measure your movement. But for any app that doesn’t come with an accessory, Apple has created a system in which your iPhone acts as the primary data source.

The iPhone 5s, iPad Air, and second-generation iPad mini all have M7 motion processors that can determine whether you’re driving, walking, running, or sleeping. When there’s no other source for motion information, like a fitness band, your iPhone will act as the main provider. So, even if you don’t have a fancy fitness wearable, you’ll still be able to benefit from HealthKit.

How does the iWatch work into all of this?
On Aug. 27, Re/code’s John Paczkowski reported that Apple will indeed premiere its smartwatch at its blowout Sept. 9 event and that it will “predictably, make good use of Apple’s HealthKit health and fitness platform.”

A few rumors have offered a very vague insight into what “good use” could mean.

In late June, The Wall Street Journal reported that the device will include more than 10 sensors to track and monitor health and fitness data. 9to5 Mac’s Mark Gurman claims that they’ll be able to measure steps taken, calories burned, and heart rate. He also says Apple is working on advanced sensors to read your hydration, sweat levels, and blood pressure.

And on top of that, Apple filed a patent in June titled “Shoe wear-out sensor, body-bar sensing system, unitless activity assessment and associated methods,” which is code for a sensor that can monitor how much iron you pump, brah.

But how do we know for sure that HealthKit will integrate with the iWatch?
Well, it’s rumored that Apple has consulted professional athletes like Lakers superstar Kobe Bryant and Los Angeles Kings right winger Dustin Brown for something. It’s unlikely that the company would be chatting with such big names unless a piece of its own custom hardware were involved.

Not to mention, Apple has been quietly hiring a team of sensor, fitness, sleep, and fashion experts since last year. This cabal includes former Senseonics hardware executive Dr. Todd Whitehurst (who specializes in blood-reading sensors), small sensor designer Nancy Dougherty, Ravi Narasimhan of Vital Connect (which measures steps, skin temperature, and respiratory rate), Philips sleep analysis scientist Roy Raymann, and a medical product manager named Divya Nag. It also hired Jean-Claude Biver of luxury watch brand TAG Heuer in July. It’s assumed that he’ll help with the device’s product sales and marketing.

We’ll know much more at Apple’s Sept. 9 product announcement. And you can watch all the news on our Apple page.

Follow Alyssa Bereznak on Twitter or email her.