Muscle strains and lumbar sprains are the most common causes of low back pain. A low back muscle strain occurs when the muscle fibers are abnormally stretched or torn. A lumbar sprain occurs when the ligaments, the tough bands of tissue that hold bones together, are torn from their attachments. Differentiating a strain from a sprain can be difficult, as both injuries will show similar symptoms. Many doctors refer to both injuries as a category called “musculoligamentous injuries” of the lumbar spine. In general, it doesn’t matter what you call the problem because the treatment and prognosis for both back strains and sprains is the same. Nearly everyone will experience low back pain at some point in their life–it is the second most common cause of missed days of work in the United States! (Only a common cold causes more missed work). Almost all of these low back injuries are due to injuries of the muscle or ligament.As said earlier, most back pain is caused by a muscle strain or ligament sprain. However, there are serious conditions that require more immediate treatment. If you are unsure of the cause of your symptoms, you should be evaluated by a physician.