First, you should choose a type of exercise you enjoy. This could be running, biking, burpees, etc. It is important that the chosen exercise be leg-dominant and that you can reach your maximum intensity fast.
As a beginner, make sure you warm up for at least 5 minutes (be in the 60–70% range of your maximum heart rate).
Do short bursts of high intensity (close to all-out) bursts followed by low-intensity or complete rest periods. Do as many of these as your fitness allows.
For example, an advanced HIIT protocol would be the Tabata protocol:
- 20 second work periods (eg. all-out sprints)
- 10 second rest periods (eg. walking)
- done 8 times
Feel free to modify these numbers, but be sure the entire workout is shorter than 15–20 minutes.
Cool down and stretch after your workout.
To keep track of your interval times, download the iOS app My Interval Timer here.