A study in Medicine & Science in Sports & Exercise found that one 23-minute HIIT workout a week for one month can lower body fat and boost aerobic capacity. In the study, 56 overweight guys did one of five protocols: either a thrice-weekly moderate-intensity workout; HIIT three times, twice, or once a week; or zero exercise.
For losing body fat, HIIT is better than moderate intensity, but surprisingly, once-a-week HIIT is nearly as good as three times. Plus, health markers like aerobic capacity and blood pressure also improved for the once-a-week HIIT group. For this to work, you can’t half-ass it—you’ve got to push hard.
Try their workout: one minute of shuttle runs at 90 percent of max heart rate, backing off to 70 percent for one minute, and repeating that 11 more times. Here are some more of our favorite HIIT workouts:
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