My brother-in-law told me a while ago about an interval training routine which I've been trying to do but am unsure whether I'm doing it right or whether it's the best thing for me. Since I don't know what it's called, I can't look it up.

It goes something like this:

Run to a heart rate of 140bpm. As soon as you reach it, walk until you reach 130bpm. As soon as you reach that, start running again until you hit 150bpm, and as soon as you reach it go back to walking until you're back at 130bpm. Keep cycling like this, adding 10 each cycle, until… well, I'm not quite sure at what point you're supposed to stop but you only do it once, and you don't decrement back down again.

Can anyone identify this routine, tell me what I've misremembered, and help me decide whether I should be doing this or something else? I've been trying it but it seems very easy compared to everything I've read about interval training being about pushing yourself to the limit.