Get Ready to HIIT It With These Strength-Training Workouts

The American College of Sports Medicine 7-Minute Workout definitely popularized HIIT and brought it to the mainstream. It's just 12 exercises! You perform each move for 30 seconds, taking a 10-second break between the exercise. This workout requires no weights, but you should have a sturdy chair on hand since step-ups are part of the workout. It's recommended to do three rounds of the workout; but c'mon, that's still only makes for a 21-minute workout.

Find the workout here: 7-Minute Workout