Why are the various permissions required by the Android app?

We understand that the various permissions requested by the Android app may raise questions and concerns, and we are more than happy to enumerate the reasons for the various permission requests our app requires.

The short answer is that each of the permission requests enables one or more of the features of our app. Find below the reasons for the various permission requested.

Contacts - Google Sign-in.
Camera - Measure your Heart Rate.
Location - Track GPS based activities.
Storage - Save charts to device storage.