ove boot-camp classes but in a time crunch? Good news: low-volume HIIT is just as effective. Less than 20 minutes of high-intensity interval training (HIIT) can reap just as many benefits as the traditional 30 minutes a day recommended by the surgeon general, according to new research published in the Journal of Physiology. “In many cases, the low-volume variations of HIIT provide comparable and, at times, superior improvements for a variety of health outcomes when compared to longer but lower-intensity aerobic training interventions,” says study author Angelo Sabag, Ph.D., of Western Sydney University in Australia.