There were tantalizing hints in animal studies, however, that this idea could be out of date. When scientists in Sweden scanned the spines of mice before and after they ran for several weeks on treadmills, the researchers noticed significant increases in the size of their spinal discs, indicating that those structures had been responding and adapting to the demands of running.
But mice, of course, run on four legs and are in all other respects not people, and it remained unclear whether running and similar activities would be good or not for the human spine.
So for the new study, which was published in April in Scientific Reports, researchers at Deakin University in Australia and other institutions decided to examine the backs of people who run and others who do not.
Eventually they recruited 79 adult men and women, two-thirds of whom said that they were runners. Some of these told the researchers that they covered more than 30 miles (about 50 kilometers) a week in training. The researchers designated these as the “long-distance” group. The others said that they ran between 12 and 25 miles a week. All had been training for at least five years.
The final group rarely exercised at all.
To ensure that people’s reported activity levels were accurate, the researchers asked their volunteers to wear accelerometers for a week.
Then they scanned everyone’s spines, using a sophisticated type of M.R.I. that precisely measures the size and liquidity of each disc.
And they found differences. In general, the runners’ discs were larger and contained more fluid than the discs of the men and women who did not exercise.
Since both greater size and increased levels of internal fluid indicate better disc health, the runners harbored fundamentally healthier spines than the people who were sedentary, says Daniel Belavy, the study leader and a professor of exercise at the Institute for Physical Activity and Nutrition at Deakin University.
Interestingly, mileage barely mattered. The discs of the people who ran less than 30 miles per week were almost identical to those in the long-distance group, suggesting that, compared to moderate mileage, heavy training does not augment disc health but also
Read more Why Running May Be Good for Your Back