I wanted to try out interval training, then I found their article which says

The interval training feature is available for PRO and Premium users on Android, iPhone and BlackBerry 10.

That’s right, even friggin Blackberry has it. So I sent a request to them. Here’s what I got:

Please note that the Application for Windows devices is no longer in development therefore we will not be adding new features to the application for the time being.

Good to know.