Elliptical Trainer is most popular cardio machine.
"Elliptical Workout" will help you to exercise less and get more benefits!
The basic idea of interval workout(HIIT) is simple: the alternation of high and low intensity.
The purpose of Elliptical interval workout(HIIT) is to burn more calories, lose more fat and build more muscle in less time. 

What app can do:
 - voice prompts (enable it in settings, Google Text-to-Speech needs to be installed)
 - share workout data with Google Fit. Enable "Share data with Google Fit" in settings.
 - calculate your heart rates zone. It's based on Karvonen heart rate reserve method. Just enter your age and resting heart rate in settings.
 - calculate burned calories,
 - has 6  workouts
 - ability to create and customize custom workouts,
 - customizing colors for each interval,
 - sound and vibration prompts on interval changing
 - list view and chart view history

How to use:
 - enter your gender, age, weight and resting heart rate to calculate burned calories and heart rates zone,
 - select workout on workouts screen. Click on workout name in the upper left corner of the main screen to get to the workouts screen, 
 - get on an elliptical trainer,
 - just follow the progress bar and the audio prompts

To restore purchases click "Restore purchases" on "Help the project" screen
If you have any issues or want to report bugs, please let me know and I'll do my best to fix them.

Interval(HIIT) cardio workouts for elliptical trainer