As good as running is for your health, it can come with some unpleasant side effects, from shin splints to chronic low back pain.

But for back pain, at least, researchers at Ohio State University’s Wexner Medical Center may have a one-step solution: Strengthen your deep core.

In a new study published in the Journal of Biomechanics, the researchers examined the way athletes’ bones and muscles interact when they run. They scaled a generic computer model of the human body to match a person’s height and weight measurements, then used motion detection technology and force-measuring floor plates to monitor every element of the person’s stride as they ran.

Then, working under the assumption that the body tries to minimize how much energy it uses while running, they used computer simulation to virtually tweak the movement of different body parts and “estimate what muscle forces would cause everything to be in balance,” explains Ajit Chaudhari, an associate professor of physical therapy, biomedical engineering, mechanical engineering and orthopedic surgery at Ohio State and the study’s lead author.

They found that if the deep core muscles — those that run along the length of the spine and sit beneath the muscles that make for a visible six-pack — were slacking, superficial muscles, such as the abdominals, were forced to take on more of the work. “That would suggest that they are going to get fatigued faster, because they’re just doing more work,” Chaudhari says. “In theory, if you had the deep core muscles contributing, you’re sharing the load among more muscles, which theoretically could allow you to have better performance or better endurance.” Engaging the deep core may also reduce strain on the spine and the possible resulting low back pain, he says.

Most people have weak deep core muscles, but sit-ups and crunches won’t cut it if you’re trying to strengthen this area, Chaudhari says. Instead, practice static core-stabilizing moves, ideally on an uneven surface. The best exercise to build a stronger deep core, therefore, is the plank, he says.