It may not be a problem with strength. Researchers are finding that changes in motor control of the back muscles of people with low back pain may be why they get back pain again. Alteration in the timing of the short fibers on the side of the symptoms may be the key. Proper timing of deep muscle contraction in the spine is essential for normal spinal movement and spinal stability.
How did they discover this? Using electromyography (EMG) to record the electrical activity of the muscles, the researchers compared the activity of short versus long muscle fibers of back and shoulder muscles. Recordings of muscle activity were taken from both sides of the spine. Surface and needle electrodes were used to get accurate EMG readings.
Measurements were taken as the subjects moved their arms forward 45-degrees. Arm movement was used because past studies have shown that such movement causes activity in the back muscles. This testing procedure gives a reliable way to measure changes in motor control of deep muscles that control spinal motion.
EMG makes it possible to tell exactly when the muscle starts to respond and the pattern of muscle activity. They were specifically looking at the response of the lumbar multifidus muscle in the back in relation to the deltoid muscle of the shoulder. They expected to find different muscle activity patterns between the two groups of patients.
What they found was that when the control group moved their arms, short muscle fibers of the multifidus started firing earlier than long muscle fibers. But in the group with recurrent low back pain, there was no difference in when the short versus long fibers were activated on the involved side. The nonpainful side for the patients behaved normally (i.e., the same as in subjects in the control group).
This particular study clearly showed a connection between abnormal motor control and recurrent back pain. It seems that just because back pain goes away doesn’t mean the muscles have returned to normal. For patients with recurrent back pain, in between episodes, their back muscles aren’t firing normally. This puts them at risk for reinjury or another acute episode of pain.
Strengthening may be what you need, but before launching into a program that might actually put you at risk for reinjury, see a physical therapist. The therapist can assess muscle strength and look at motor control strategies. As a movement expert, the therapist can help you regain normal motor function and help you regain the proper sequence of muscle contraction needed for spinal movement and stability.