Causes

Back pain often develops without a cause that your doctor can identify with a test or an imaging study. Conditions commonly linked to back pain include:

• Muscle or ligament strain. Repeated heavy lifting or a sudden awkward movement can strain back muscles and spinal ligaments. If you're in poor physical condition, constant strain on your back can cause painful muscle spasms.
• Bulging or ruptured disks. Disks act as cushions between the bones (vertebrae) in your spine. The soft material inside a disk can bulge or rupture and press on a nerve. However, you can have a bulging or ruptured disk without back pain. Disk disease is often found incidentally when you have spine X-rays for some other reason.
• Arthritis. Osteoarthritis can affect the lower back. In some cases, arthritis in the spine can lead to a narrowing of the space around the spinal cord, a condition called spinal stenosis.
• Osteoporosis. Your spine's vertebrae can develop painful fractures if your bones become porous and brittle.