You can write your own code using Samsung Digital Health SDK and exchange data with S Health app. To enable data exchange between your app and S Health you need Partner Apps Access. From S Health app you can sync these data with your Gear using Gear Manager app.
For independent app in Gear which can measure different Human Activity data, you can use Human Activity Monitor API in Tizen. You will be able to measure
- Heart Rate
- Wrist Up
- Step Status
- Speed
- Walking frequency
- Walking Activity
- Sleep status
And another method is you will write your Health application using Samsung Digital Health Android SDK in android. But this app must be SAP enabled to send these Health data to Gear. To use SAP you have to use Samsung Accessory SDK. In Gear part you can write your app either in Native or in Web. This is call companion app. To transfer data between companion apps you have to connect your Gear with Android phone using Gear Manager.