A structured training approach alternating high-intensity exercise with lower-intensity recovery periods, effective for improving specific fitness attributes.
The concept is to build speed (power) with workout intervals as long as possible for an athlete to go hard, but not so long that they’re slowing down. In most cases, this means starting with short intervals, such as 8 seconds of work, and building up to longer intervals, such as 30 seconds of work. It is also common to have intervals in other training zones that are one zone higher than your aerobic capacity-building zone.