I sometimes sport as many as four wearable devices. And my Exercise With It folder on my iPhone goes on for four screens. So I’m a prime candidate for the new health software Apple just unveiled.  

“The information gathered by [health and fitness] applications lives in silos,” said Apple executive Craig Federighi in a keynote presentation at the company’s Worldwide Developers Conference, which is taking place this week in San Francisco.

As part of a set of new features in iOS 8, Apple’s newest version of its software for iPhones and iPads, Federighi presented HealthKit, a new feature in iOS 8, and an accompanying Health app.

Apple is initially partnering with Nike and the Mayo Clinic to incorporate HealthKit in their apps. But the company is hoping to get other hardware and software developers to link HealthKit as well.

An Unhealthy Lack Of Standards

The problem Apple will run into: No one agrees on how to measure even very simple health metrics, like the amount of activity one engages in every day. Is it minutes of activity, as apps like MyFitnessPal and Human prefer? Made-up, proprietary metrics like Nike’s Fuel or Under Armour’s Willpower? Or steps, as made popular by various pedometer devices like those made by Fitbit and Jawbone? And how will Apple reconcile all of those together into a single store?

Sleep quality, likewise, is fraught with disagreement: What constitutes “light” or “restful” sleep? Can devices tell by motion whether or not you’re really asleep—or lying still, eyes wide open?

Even heart rate, which you’d think could be reduced to a single number, is actually a complex graph over time, and devices and software disagree about how often to sample it and how to account for irregularities in the biological signals that we measure.

Apple has a lot of work to do—which means HealthKit is just a beginning, not a cure for what ails the digital-fitness industry.