Luto, from what I read on the website you'd go as fast as you can during the bursts....then slow back down until your heartrate returns to your warm-up heart rate....then repeat.
My heart-rate while jogging would be around 130 and I imagine the bursts would be up in the 170's for those few seconds. I'm going to try that out at the gym tonight. I'd much rather do 20 min. cardio than longer sessions.