What are they?
Continuous, alternating bouts of faster running followed by slower running. Depending on the goal of the workout and program goal, you can make these workouts act as a introduction to stamina building, or extremely specific to your goal race by manipulating both the work and rest interval duration and intensity.
How and why do they work?
This training modality will challenge the central and peripheral components of the cardiovascular system, creating a stress-recovery paradigm that enable your body to become efficient at dealing with the response of a dynamic training load in an acute and cumulative manner.
Alterations for 5K
This type of training stresses the rest interval of the session and is a great fun way to build stamina and connect specific endurance, a pillar of successful running.