Interval training alternates periods of intense effort with periods of moderate-to-low intensity effort. An increasingly popular model of exercise, research suggests that by alternating bursts of high and low intensity activity, interval training can super-charge fat-burning, boost metabolism, and improve cardiovascular fitness (for example, a 20 minute workout of alternating high/low-intensity periods burns more calories than a 20 minute workout of steady intensity). Some research also suggests interval training also builds lean muscle tissue faster than steady state training. Popular forms of interval training include Tabata Protocol and The Little Method. For more on interval training, check out the articles below: