health-kithealth.app
Unless I am mistaken, HealthKit/Health.app will automatically track some BlueTooth sensors, like heart rate straps? Is that true?
Is it also true that other sensors do not work this way, and only work when a 3rd party app is running. Is that also true?
If so, is there a list of such "auto track" devices?
Best way I found was to: Open Health App and head to Health data < All and use the arrow on the upper right of the screen then choose Export.
It will take a while if you have a data. You'll be able to get a ZIP file that you can mail to yourself.
Just use XCode and you should (at least!) be able to read your data. You could then use dropbox to sync it with your other devices.
Go to Setings > General > Restrictions and enable it.
Do nothing and re-enable it, the app should be back. On iOS 10 and later, you might also need to go to the App Store and reinstall system apps so be sure to try that as well.
Last - look for any profiles in settings in case someone managing your device has prevented use of that app systematically. You can generally remove the profile or ask them to reassign your device if you should have access to the health app and store health data on your device.
Best Answer
There are no "auto-track" devices per se. You have to go in and give certain apps or devices access to the Health data.
As detailed on Apple's website, you need to choose the fitness app or accessory you want to use, and this will connect it to your Health app.
When you connect apps as a source of data to your Health app, they should automatically push in the data, but you might have to open the app for it to trigger. On the other hand, there are many, many devices that support automatic synchronization, like the Garmin Forerunner 220.
Unfortunately there are too many devices supporting synchronization with an iOS device, but most apps or devices that are capable of synching with the Health app support auto-synchronization when in close proximity to the device.
You can see a list of HealthKit compatible devices here: http://www.applehealthkit.com/compatible-devices-apps/.