A natural response to low back pain is to stop using the sore muscles in your back. But after a while, the pain and inactivity can make these muscles shrink. Can exercise therapy get the muscles back in good shape?
This study was part of a series to examine the effects of exercise therapy on low back pain. In the first part of the series, researchers found that exercise therapy improved the muscular strength and endurance of patients with low back pain. In this segment, researchers looked at the muscles themselves, to see if improvements in strength were related to actual changes in the muscle tissue.
Fifty-nine patients participated in the study. Twenty-nine were men; 30 were women. They each took part in one of three exercise programs: physical therapy, muscle training with special devices, or low-impact aerobics. Patients did exercise therapy twice a week for three months.
Before and after treatment, the authors took an MRI scan of each patient’s torso. This gave a computerized image of patients’ back muscle tissues. The authors also took muscle samples from each patient’s back, to study under a microscope.
Before exercise therapy, the size of patients’ back muscles was directly related to their strength. That is, the bigger the muscle, the stronger it was. The presence of certain muscle fibers was important to keeping muscles from wearing out during physical tests.
The authors expected that patients’ muscles would get bigger during exercise therapy, to explain their increased strength after treatment. Yet exercise therapy didn’t seem to make much difference in the size of patients’ muscles. Trunk muscles tended to get slightly bigger for patients in the physical therapy and aerobics groups, and slightly smaller in the group that used special training devices. But changes in muscle size weren’t related to improvements in muscle strength. And the actual fibers that made up the muscles didn’t change at all.
No changes occurred at the muscular level, suggesting that improvements were due to improved muscle action and coordination. However, this time span might not have been enough time to show changes within the muscle cells. Muscles may change more slowly, especially when they’ve stopped working due to back pain.
This study may have captured the beginning of a long process of muscular change. A longer study period and other specialized ways to explore the back muscles may show that more than three months is required to reverse the harmful effects of back pain on the health of these muscles.