Exercising by doing interval training, not weight lifting, could be the secret to staying young, according to a new study published Tuesday in the medical journal “Cell Metabolism.”

High-intensity aerobic interval training–or exercising in bursts of moderate and high-intensity running, cycling, or other aerobic activity–may help to reduce the effects of aging at a cellular level, researchers found.

Scientists analyzed three groups of people who were exercising by doing high-intensity aerobic interval training, resistance training, or a combination of the two, over the course of a 12-week period.

While scientists found that all three types of exercise improved participants’ lean body mass, at a cellular level, they found that the group participating in the high intensity interval training also saw improvements in the exercise capacity of their muscle’s mitochondria. As people age, their mitochondria, which are responsible for producing energy for your cells, become less efficient.

High intensity interval training essentially “reversed” many “age-related differences” in aspects of elderly participants’ mitochondria, the researchers wrote in the study’s summary.