Once reserved for competitive athletes, interval training is a real option for all of us. With this approach, you can squeeze your workouts into shorter time periods, and possibly derive even greater benefits from them. The principle of aerobic interval training is to vary the intensity of your activity, alternating periods of strenuous exertion with periods of recovery. For the runner, this may mean alternating four-minute sprints with three-minute walks, using the walk to recover from the heavier exertion. Nearly every aerobic activity can be approached in this fashion. Compared to standard, steady exercise, interval training produces greater increases in endurance, oxygen use and general fitness. In addition, studies show that interval training has beneficial effects on body weight and blood pressure.
"Interval training defined: Shorter and fewer sessions with a higher intensity." Emilie Fedders.