Your lower back might not seem to play a big role in running, but holding your body vertically for a long time can make you vulnerable to injury—especially in the lower-back area. That's why a group of researchers at The Ohio State University Wexner Medical Center, with the help of the National Institutes of Health (NIH), conducted a simulation study to figure out why runners may experience this type of pain and what could be done to prevent it long-term. (Related: Is It Ever Okay to Have Lower-Back Pain After a Workout?)
Lead author of the study, Ajit Chaudhari, Ph.D., an associate professor at OSU's department of kinesiology, created virtual models based on eight real runners to see how the bones and joints are affected by running (see photo).
Photo: The Ohio State University Wexner Medical Center
Once the simulations were complete, researchers manipulated different muscles in each runner, weakening and fatiguing them to see how the rest of the body compensates. It turns out that having a weak core could increase the load on your spine in a way that may lead to lower-back pain.
"The muscles that compensated when the deep core was weak caused greater shear forces (pushing and pulling of the vertebrae) in the lumbar spine (where the spine curves inward toward the abdomen)," Chaudhari tells Shape. "Those forces can cause the individual vertebrae to slide past each other or move side to side, which puts more stress on parts of the spine that can cause lower-back pain. Essentially, when you have weak or non-active deep core muscles, you might still be able to run the same way, with the same form, but you'll end up overloading the lumbar spine in ways that can cause injury."
But Chaudhari isn't talking about your abs. "Those are the muscles you can see—your 'beach muscles'—and they're right underneath the skin and tend to be the furthest away from your spine," he says. The muscles in your deep core are closer to your spine and tend to be shorter, connecting one part of the lumbar spine to another. "When strong, these muscles hold the spine in place, which leads to less injury," Chaudhari says. (Related: The Ab Myths You Need to Stop Believing Right Now)
It's common for people, even well-conditioned athletes, to neglect their deep core, Chaudhari explains. While sit-ups and crunches might work your abs, they do little for your deep core. Chaudhari recommends focusing on exercises that force you to hold your core in a stable position, like planks and bridges on unstable surfaces such as a Bosu ball or balance disc. (Related: These Ab Exercises Are the Secret to Preventing Lower-Back Pain)