• December 2006, Canadian researchers reported that just two weeks of interval training boosted women's ability to burn fat during exercise by 36%.
• In January 2007, a six-month study was published showing that adding aerobic exercise had no additional effect on body composition, over diet alone.
• In June of 2007, a twelve-month study was published which had the subjects doing six hours of aerobic exercise per week, training six days a week, for one year. The average weight loss was only three pounds for that one-year period.
• According to a British study, levels of Human Growth Hormone, which assists in building muscle and burning fat, skyrocketed 530% in subjects after just thirty seconds of sprinting as fast as they could on a stationary bike.
• Australian fitness researchers had eighteen women perform twenty minutes of interval training on a stationary bike — eight-seconds of sprinting followed by twelve seconds of recovery — throughout the workout, three days a week.
The women lost an average of five-and-a-half pounds over fifteen weeks, without dieting. Similar groups performing forty minutes of moderate cycling, three days a week, actually gained a pound of fat over the same period. Two of the heavier women who did intervals dropped eighteen pounds.
• In a side-by-side comparison, researchers at McMaster University in Ontario measured fitness gains in eight interval exercisers — using twenty to thirty minute cycling workouts that included four to six thirty-second sprints — against eight volunteers who pedaled at a lower intensity for 90 to 120 minutes.
After two weeks, the interval group was every bit as fit as those who worked out three to four times as long.
