What causes lower back pain There are many different causes to back pain. Sometimes back pain can occur for no apparent reason, but the two main reasons are either due to an injury, or just the fact that a weakness exist in that region. Lack of muscle tone and excess weight, especially around your middle, commonly cause and aggravate back pain. Poor posture can add stress to the muscles and joints, causing fatigue and injury. Add to that the daily stresses and strains you put on your back, such as carrying out the trash, sitting in your car or truck for long periods of time, lifting something heavy and incorrectly or just applying the brakes in your car. Even minor damage to any one component of your back's structure can upset the delicate balance and make movement painful. Your body will then try to protect this area by contracting the muscles surrounding the area. The contracted muscles not only causes the pain you experience, but they also slow down circulation to the area, which ultimately diminishes the necessary oxygen flow and prevents the body to heal itself. Damage and associated pain can occur at any point of your spine. However, the most common site for pain is in your lower back because it bears the majority of your weight, and is therefore exposed to the most pressure. Common causes of back pain Muscle strains and spasms - Aches and pains, commonly called "lumbago", usually signal strained muscles, tendons or ligaments or inflamed joints along your spine. If you strain your back, you may feel immediate pain or develop soreness and stiffness later. Muscle spasm usually occurs after some kind of injury (however small it may have been). Spasm is your body's way of saying "Hey - watch out!" It is designed to immobilize you and prevent further damage. Osteoarthritis - Commonly referred to as "arthritis", this disorder affects nearly everyone past the age of 60. Overloading and injury can slowly deteriorate cartilage, the protective tissue that cover the surface of vertebral joints. Discs between vertebrae become worn and the joints rub together with greater force than normal. The surfaces where they meet - called facets - compress and becomes irregular, the cartilage wears out and gradually your spine stiffens and looses flexibility. Bony outgrowths - called spurs - also develop and the result may be pain. Sciatica - About 10 people in 100 with back pain may experience "sciatica". Named after the sciatic nerve that extends down each leg from your hip to your heel, this condition can cause inflammation and compression in your lower back and buttock. You may feel pain radiating down to your lower leg. Tingling, numbness or muscle weakness can also accompany this condition.Usually the pain resolves on its own, however, severe nerve compression can cause progressive muscle weakness. Osteoporosis - The amount of calcium in your bones decreases as you get older. Loss of calcium weakens your bone structure, and in some cases your vertebrae becomes compressed which results in back pain. One in three women older than 50 is affected by osteoporosis. Frequently, structural changes occur in the spinal column that may cause many women to develop a crooked stance or a stooped-shoulder posture called "dowager's hump". Herniated disc - A "slipped disc" is how you might describe this problem. While the discs don' t really "slip", normal wear and tear, strain or injury may cause a disc to bulge or rupture (herniate). When a disc herniates, parts of the disc can protrude from their normal position between your vertebrae. Pain can result when a fragment of the herniated disc places pressure on an adjacent nerve. Less Common Causes of back pain Spinal stenosis - spinal stenosis involves a narrowing of your spinal canal. It can develop because of a congenital defect, but usually results from osteoarthitis. As discs between vertebrae become worn and the space between the vertebrae narrows, vertebrae and soft tissue can move inward into your spinal canal, compressing the nerves. Ankylosing spondylitis - Anklosing spondylitis, a serious form of arthritis, is an uncommon type of back pain that typically affects young men. At first, it causes pain and stiffness in the joints of your spine. With time, the disease causes your vertebrae to fuse together, limiting movement in your back. Infections and tumors - Rarely, infections can develop in your vertebrae. Tumors may also spread from other parts of your body, such as your breasts, prostate or lung, to cause pain. But this is not common. In addition, tumors typically don't originate in your spine and, if they do, are usually benign.