In runners' circles it's usually called "The Galloway Method" after Jeff Galloway, a running guru who promotes an alternating run/walk pace as a way to increase the distance you can run while keeping away from injuries. He doesn't go for quite so short an interval; it's usually something like 3 minutes of running to one minute of walking (or more as you get fitter and faster). Certainly helped get me through my first half-marathon.