The afterburn effect is another term for excess post-exercise oxygen consumption. It refers to the continued state of caloric burn experienced after intense physical exertion, according to Men's Health. It is believed that this metabolic state increases the potential for weight loss. It also supports the theory that high-intensity interval training is much more efficient than most traditional forms of exercise.
High-intensity interval training is a form of exercise that alternates between powerful surges of physical activity and short periods of decreased exertion or complete rest, explains Charlotte Hilton Andersen for Shape. HIIT is intended to condense a full workout into about 15 to 20 minutes. Men's Health states that HIIT can increase the body's caloric expenditure by up to 10 percent in a single installment. The metabolic state achieved with HIIT is believed to last for up to three days, hence the term afterburn.
HIIT is not the only way to achieve the afterburn effect. Any form of vigorous activity performed at 70 to 85 percent of the individual's maximum heart rate often works. Studies show that after vigorous exercise for 45 minutes, the body burns more calories for a 14-hour period after than on days when no exercise is performed at all.