The Tabata™ protocol is a high-intensity cardiovascular workout that involves 3 to 8 rounds of 20 seconds of high intensity work, plus 10 seconds of rest between rounds. Clients aim to reach maximum heart rate during the work time during each round. For more about what Tabata is, how it was developed and the science behind it see this article.
This method is more effective at improving the body's aerobic and anaerobic capacity compared to regular moderate-intensity aerobic exercise programs. It is effective for people of all ages and states of fitness.