Last year I injured my back in a job-related accident. After being off work for six months and completing a rehab program, I came back as good as new. Two months later I started having back pain again. What's going on?

Studies show that previously injured spinal structures are at risk for reinjury. It looks like repeated or excessive loading on already damaged soft tissues can cause the disc to wear out faster. The result can be chronic low back pain (LBP).

Certain work tasks also increase the risk of LBP. Compression and shear forces in the spine that occur during lifting seem to be the biggest factor in reinjury. A recent study from Ohio State University tried to find out which activities or work tasks increase spine loading. The idea is to restore normal motion when using these movements.

The researchers found that previously injured workers change the way they lift objects. There is increased muscle holding and guarding. The workers are unwilling to load the spine fully. Many are also heavier and larger than subjects without back pain. This puts an extra load on the spine.

Future rehab programs may be able to use computers to monitor muscle contractions. A software program will help patients regain normal motions.