Finding the motivation to run more can be difficult but the promise of youth might do it for some people. A new study out of Deakin University in Australia found that people who run regularly have younger bone marrow than those who are sedentary. 

The study, published in the Journal of Bone and Mineral Research last week, involved more than 100 participants. The researchers found that people who ran five and a half miles a week had bone marrow that was a year younger than they were, and people who ran 12.5 miles a week had marrow that was up to eight years younger than sedentary participants, according to a release.

The researchers studied whether or not exercise was associated with lower levels of marrow adipose tissue, the tissue that is present in higher rates in people with fragile bones. They found that people who exercised more had lower levels of this tissue. 

"Humans are born with predominately red blood cell producing bone marrow, however with age, this converts into a yellow fatty marrow," said the lead author on the study, Daniel Belavy, according to a release. That yellow-fatty marrow, while natural, is what can make bones more fragile and can weaken bones in the pelvis, legs, and back causing more severe issues like osteoporosis.

The runners were more likely to have younger bones than those who cycled or did another aerobic activity that did not involve the force on the bones that running does. in fact, those who cycled were found to have similar bone marrow to the people who did no exercise. The study is the first to find that the type and amount of certain exercises can affect bone marrow conversion or the youthfulness of bones, it said.

All of the participants were between the ages of 25 and 35 years old and had no history of spine or bone disease said the study. The people who ran the most had the youngest marrow, but Belavy said that even people who jogged regularly would likely see the benefits of it in the form of younger bones.