Scientists are still sorting this all out. A group of researchers in Norway offer some new insight. They measured muscle strength, size, and endurance in two groups of back pain patients. One group had a lumbar fusion; the other tried an exercise program. The exercise program also had a lecture on anatomy and pain in the back.
The patients in the exercise group had the best result. They had greater muscle strength, density, and endurance. The results stayed the same even when measured a year later. The scientists aren't sure why the fusion group didn't do better. Recovery of some muscle strength is possible just with daily activities.
The muscle atrophy and weakness in the fusion group was more than the researchers expected to see.