Been itching to build some fitness apps using Google's Android-based Google Fit framework? There's now a preview software development kit (SDK) for you to play with.
The preview version is available as part of a Nexus 5 or Nexus 7 system image. Right now you can only use it to access local data -- Google says the cloud backend is coming "soon". The full SDK is expected out later this year (and apps can't be published to the Play Store until that happens).
Google Fit Preview SDK now available [Google Developers Blog]