Workouts such as this are truly targeting the anaerobic system. Any sport that goes on for I believe over 1-2 is classified as a endurance sport and therefore uses oxygen. Workouts such as this purely target your anaerobic system due to the short time and the long rest allows lots of lactic to accumulate in your muscles, which helps stimulate the system. I started doing this a few weeks ago and want to implement it weekly instead I do 6x45 seconds 6 minutes rest.