Dear Doctor: I just heard that instead of causing injuries, running may be good for your back. Is this true? If it is, I’m going to lace up my shoes and head back out to the trail!

Dear Reader: Running is one of those physical activities that, over the years, has accrued an almost mind-bending cache of contradictory advice. So it’s no wonder that the results of a new study, which suggests that running can improve the health of the discs in your spine, have caught you by surprise.

Let’s start with a look at the spinal column, which as we’ve said before is a marvel of engineering. With a minimum of moving parts, this gently s-shaped curve of bone, cartilage, collagen and protein gels supports the body and gives it structure. It allows multi-directional movement and protects the vital bundles of nerves that connect the brain to the rest of the body.

The vertebrae are the series of load-bearing bones that articulate the spine. These are connected to one another by gel-filled discs, which also act as shock absorbers. But the same interlocking structure that lends flexibility to the spine is also its most vulnerable feature.

How the repetitive stress of running affects the various parts of the spine, particularly the discs, has long been a subject of debate. In the study published last spring, scientists from Australia set out to answer the question and learn whether intervertebral discs can be strengthened. To that end, they studied the spines of 79 men and women between the ages of 25 and 35. One-third of them were not runners. In fact, that group rarely exercised at all. Of the runners in the study, all had been training for at least five years, and regularly logged anywhere from 12 to 30 miles per week.

With the use of advanced imaging techniques, the researchers measured the size and resilience of each participant’s spinal discs. The results were surprising. The runners in the study, whose regular exercise regimen placed repeated demands on the shock-absorbing qualities of the spine, had intervertebral discs that were larger and filled with more fluid than did the group who rarely exercised.
That is, their discs were healthier than those of the non-running participants.

Even more intriguing was the fact that the size of the vertebrae of the joggers, who totaled 12 to 25 miles per week, and the long-distance runners, who ran as much as 70 miles per week, were virtually the same. That is, total mileage didn’t matter. Longer runs didn’t make the spine healthier, nor did they cause deterioration.

Those of us who aren’t runners will be happy the scientists didn’t stop there. By parsing their data even further, they discovered that the health effect on intervertebral discs begins at a pace of 4 mph, or a brisk walk.

Although a single study can’t definitively answer whether running is good or bad for the back, the results here add a layer of fascinating and encouraging information for runners and walkers alike.

Eve Glazier, M.D., MBA, is an internist and assistant professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and primary care physician at UCLA Health.