A study from the American Physiological Society shows that minutes of hard exercise can lead to all-day calorie burn. A single session of sprint interval training increases total daily energy expenditure. Good enough to feel like a fantasy, exercisers can really burn as many as 200 extra calories in as little as 2.5 minutes of concentrated effort a day — as long as they intersperse longer periods of easy recovery in sprint interval training. This could make exercise more manageable for would-be fitness buffs by cramming truly intense efforts into very little time. However, maintaining the maximum effort needed to exercise at peak intensity over the 30-second sprints could prove tricky for many people to maintain on their own without help. The way this could work in the real world is with the guidance of a personal trainer.