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Runners: Don't Neglect Your Core Muscles

by Andrea Klausner, MS, RD  

If you’re a runner, don’t ignore your deep core (trunk) muscles: Strengthening them may help prevent low back pain, according to a small recent study in the Journal of Biometrics.

The deep core muscles are bundles of muscles deep in the abdomen, low back, hips, and pelvis that act together to stabilize the spine and support posture; some attach directly to the lumbar spine. These are in contrast to the superficial core muscles, whose primary function is to produce movement and transmit forces to the arms and legs. The superficial core muscles are the ones that can give you a “six-pack” if you strengthen them enough, whereas the deep core muscles cannot be seen, no matter how strong they are.

Many beginner and experienced runners alike tend to focus on trying to run faster and longer while neglecting to exercise their core muscles, especially their deep core muscles—which may help explain why many of them experience chronic low back pain.

For the study, researchers at Ohio State University used motion detection technology and high-speed cameras to analyze how the muscles of eight healthy participants moved, and the force they exerted on the ground, while they ran around a track in a lab. From these baseline profiles, the researchers then did computer simulations to see how the body compensates when muscles are weakened, individually or together.

It turned out that as the deep core muscles were progressively weakened as a whole, the superficial trunk muscles around them had to work harder to maintain normal running motions, resulting in faster muscle fatigue and greater load on the vertebral column of the spine, which can increase the risk of muscle strain and degenerative disc disease.

As for individual muscles, weakening of the deep portions of the erector spinae—which runs up both sides of the spine—led to the greatest compensation, suggesting that this muscle “plays the largest and most unique role” when it comes to proper running form, the researchers noted. “Sufficient strength of the deep core musculature as a whole, and especially the deep erector spinae, may reduce a runner’s risk of developing low back pain.”

What you can do

For runners to prevent back injury, it’s not simply a matter of doing sit-ups, crunches, or other abdominal exercises that work the superficial trunk muscles. Rather, the focus should be on static exercises that go deeper, such as planks and side bridges. Exercising on an unstable surface—using exercise balls or balance boards, for example—may activate core muscles more than exercising on a stable surface. Back extension exercises help strengthen the erector spinae muscle, in particular. Pilates and yoga are other good ways for runners to get a core workout. But if you already have back pain (or other musculoskeletal issues), you should be medically evaluated before starting any exercise program.

This article first appeared in the UC Berkeley Wellness Letter.