Health App - iPod Touch 6. What can you do manually (no wifi)?

I'm guessing new iPod Touch 6 will have iOS 9 at this point. Obviously, if you're out running (or whatever), you're not connected to wifi / gps / app-trackers.

It says you can input Health data manually. What useful things can you input manually (without assistance of 3rd-party app)? Does Health then calculate anything based on that?

Is there anything it can track while you're not connected to wifi (and without 3rd-party app)?

... I prefer to keep my data self-contained and not accessible to be uploaded anywhere else.