The one I use is a 4 minute timer. It has your do a tabata (20 second interval of explosive/plyometric exercise) with 20 second breaks in between each interval.

Interval workouts boomed in popularity, using a variety of work/rest intervals. How do newer HIIT videos compare? The term HIIT didn’t just get watered down; it mutated.

HIIT is unique in that it's a surprisingly effective workout while requiring only a minimal amount of time.

Bit Timer: A Brilliant App That Makes Interval Workouts Easy This iPhone app is so elegantly designed that, while you still won’t want to work out, you’ll really wish that you did.

A jump rope A timer or exercise app that allows you to program 20-second intervals A box or stair that you can safely jump onto How Often If you’re new to HIIT, start with one session per week.

The pair found that the first-timers not only had positive attitudes toward HIIT, but that participants also reported feeling more positive about the exercise regimen if they listened to music ...

Gym rats know the power of HIIT—high-intensity interval training. Those all-out, repeated blasts of activity seem daunting, but those who try it swear by it. There’s a HIIT for the mind too ...