10-20-30 training? What the hell is that? For one persuasive thing, it’s the favorite interval training program of New York Times health columnist Gretchen Reynolds. For another, it was invented by Jens Bangsbo, a professor of physiology at the University of Copenhagen in Denmark, who was disappointed by the failure of interval training to improve the fitness of many out-of-shape people. That failure, it turned out, stemmed from the study group’s failure to stick with the program, so Bangsbo decided to devise a program that would be more like fun and less like work. As Reynolds writes in the New York Times, “The essentials of 10-20-30 training are simple. Run, ride or perhaps row on a rowing machine gently for 30 seconds, accelerate to a moderate pace for 20 seconds, then sprint as hard as you can for 10 seconds. (It should be called 30-20-10 training, obviously, but that is not as catchy.) Repeat.” Reynolds like the program because it doesn’t require any high-tech monitoring, or even a gym membership. Or a stopwatch. Anyone can count to 30. She also likes the brevity–only 10 seconds– of the most grueling leg of the workout. Finally, Reynolds reports that the program works–proven, you guessed it, by research conducted in Bangsbo’s lab. See more in the video below.