"If you wish to try 10-20-30 training, Dr. Bangsbo recommends starting by replacing one or two of your normal weekly workouts with a 10-20-30 session.
Warm up with an easy jog (or pedaling or rowing), then ease into the intervals. The 30-second portion should feel relaxed; the next 20 seconds moderately hard; and the final 10 seconds a full gallop. “The aim is to cover as much distance as possible in those 10 seconds,” Dr. Bangsbo said.
Do five of the 10-20-30 intervals in a row without pause, then rest for two minutes by standing or very slowly walking about. Repeat the five consecutive intervals one more time, cool down, and you are done. The whole session, minus warm-up and cool-down, will have lasted 12 minutes.
If you are already in fine shape, Dr. Bangsbo said, add another set of the five uninterrupted intervals.
Rest the next day, he said, or very lightly exercise; don’t do two of the intense interval sessions in a row. Although a smaller percentage of runners in the 10-20-30 group sustained injuries than did runners in the control group in his study, “we recommend very slow progress.”"