http://www.ideafit.com/fitness-library/hiit-vs-continuous-endurance-training-battle-of-the-aerobic-titans A look at the science of high-intensity interval training. The fitness industry is seeing a surge of interest in high-intensity interval training (HIIT), a burst-and-recover cycle that can offer a viable alternative to continuous aerobic exercise. HIIT, which pairs quick bouts of high-energy exercise with low-effort rest intervals, is not exactly a new idea. As early as 1912, the Finnish Olympic long-distance runner Hannes Kolehmainen was using interval training in his workouts (Billat 2001). As our knowledge of HIIT has increased, exercise scientists have demonstrated that HIIT can boost the performance of competitive athletes; improve the health of recreational exercisers; and provide the benefits of continuous-endurance training with fewer workouts. The standard way to improve cardiovascular fitness is to increase the vol