Good news for the time crunched: Just 10 minutes of interval training can have the same metabolic and cardiovascular benefits as 45 minutes of continuous moderate exercise. The study from McMaster University in Ontario, Canada, examined the effects of a 12-week cycling program in three groups of sedentary men in their 20s. The control group did no exercise; one group cycled for 45 minutes three times per week at moderate intensity; and the third group interspersed 20 seconds of all-out sprints with two minutes of recovery pedaling for 10 minutes three times per week. At the end of the 12 weeks, both exercising groups had nearly identical improvements in blood sugar control, cardiovascular fitness, and muscular fitness at the cellular level. So swapping 150 minutes of moderate-intensity workouts for just 30 minutes of interval training every week will help maintain fitness and free up two hours per week.