From Coach Leo

High-intensity interval training (HIIT),

is an enhanced form of interval training,

an exercise strategy alternating short periods of intense anaerobic exercise with less-intense recovery periods.

HIIT is a form of cardiovascular exercise. Usual HIIT sessions may vary from 4–30 minutes.

These short, intense workouts provide improved athletic capacity and condition,

improved glucose metabolism, and improved fat burning.

From Chan chung Yeung