(COLUMBUS, Ohio) – Low back pain is a common complaint among both elite and recreational runners, but the true cause of it remains a mystery. So researchers at The Ohio State University Wexner Medical Center used motion capture technology to observe how a runner’s muscles work while they’re in motion.

“We measured the dimensions of runners’ bodies and how they moved to create a computer model that’s specific to that person. That allows us to examine how every bone moves and how much pressure is put on each joint ” said Ajit Chaudhari, an associate professor of physical therapy and biomedical engineering at The Ohio State University Wexner Medical Center who led the study. “We can then use that simulation to virtually ‘turn off’ certain muscles and observe how the rest of the body compensates for that.”

What they found is that weak deep core muscles force more superficial muscles like the abs to work harder and reach fatigue faster. When those superficial muscles are doing the work the deep core should be doing, there are often painful consequences. “When your deep core is weak, your body is able to compensate in a way that allows you to essentially run the same way,” said Chaudhari. “But that increases the load on your spine in a way that may lead to low back pain.”

Chaudhari says it’s very common for even well-conditioned athletes to neglect their deep cores, and there is a lot of misinformation online and in fitness magazines about core strength. To strengthen the deep core muscles and prevent injury, runners should focus on exercises that force them to fire their core to hold their body in a stable position. Try exercises like planks or bridges on an unstable surface such as a Bosu ball or balance disc.