HIIT—or high-intensity interval training—is having a serious moment. Celebrities from Karlie Kloss to Emmy Rossum swear by this workout regimen to stay in top shape. But what is it exactly, and why is it so special? "High-intensity interval training is basically any workout that alternates between intense bursts of activity and fixed periods of less-intense activity or even complete rest," fitness expert Tanja Djelevic told our sister site Byrdie. Although many people have already discovered HIIT’s intense fat-burning benefits, a new study shows that it may also reverse our body’s aging process.
The research team behind the study in the journal Cell Metabolism enlisted an equal number of men and women in two different age groups (18 to 30 and 65 to 80) and split them into three workout groups: the first using a HIIT cycling regimen followed by two days of quick, treadmill walking; the second doing only strength training; and the last focusing on combination training without intervals. After 12 weeks, the Mayo Clinic researchers found that those following the HIIT regimen benefited the most at the cellular level—with the younger group showing a 49% increase in mitochondrial capacity and the older group showing a boost of 69%. Our mitochondria control all of our breathing and energy-producing functions in our cells, and they tend to deteriorate with age. If our mitochondria stay young, then so can we, right?
Be sure to read This One-Minute Exercise Is More Effective Than a Full Workout, and tell us what your favorite type of HIIT is in the comments.