Nearly everyone at some point has back pain that interferes with work, routine daily activities, or recreation. Low back pain is the most common cause of job-related disability and a leading contributor to missed work.

Types of low back pain
Acute or short-term low back pain generally lasts from a few days to a few weeks. Most acute back pain is mechanical in nature — that is musculoskeletal low back pain.

Musculoskeletal low back pain can be caused by problems with the alignment in your vertebrae, pelvis, or sacroiliac joint (where your spine meets your pelvis), tightening or shortening of muscles in the area, lack of or too much mobility in your spine or a specific syndrome termed "myofascial pain syndrome". Myofascial pain is pain arising from active trigger points in a muscle or its fascia (connective tissue around the muscle). A trigger point is a tender, irritated area that can cause pain in areas along the muscle; an event called "referred pain". This referred pain can usually be reproduced when the trigger point is "palpated", or pushed on. The pain can be felt at rest, as well as when the muscle is being used. Trigger points over time cause the muscle to shorten, leading to a tight, pulling, or stretched feeling. Problems with your alignment can trigger nerve receptors in joints and other areas.

Chronic back pain is measured by duration — pain that persists for more than 3 months is considered chronic. It is often progressive and the cause can be difficult to determine.

The factors that contribute to back pain include:

•    Poor posture (Slouching when sitting)
•    Improper footwear and walking habits
•    Improper lifting, lifting heavy objects
•    Straining individual muscles
•    Calcium deficiency
•    Prolonged sitting, especially in a chair that does not adequately support the back
•    Sleeping on a mattress that is too soft
•    Kidney, bladder, and prostate problems
•    Stress
•    Pregnancy
•    Female pelvic disorders
•    Constipation may produce back pain
•    Arthritis
•    Rheumatism
•    Bone disease
•    Abnormal curvature of the spine

The conditions associated with low back pain

Conditions that may cause low back pain and require treatment by a physician or other health specialist include:
1.    Bulging disc (also called protruding, herniated, or ruptured disc). As discs degenerate and weaken, cartilage can      bulge or be pushed into the space containing the spinal cord or a nerve root, causing pain.
2.    Sciatica : The compression of sciatic nerve causes shock-like or burning low back pain combined with pain through the buttocks and down one leg to below the knee, & it reaching the foot.
3.    Spinal degeneration : From disc wear and tear can lead to a narrowing of the spinal canal.
4.    Spinal stenosis related to congenital narrowing of the bony canal predisposes some people to pain related to disc disease.
5.    Osteoporosis is a metabolic bone disease marked by progressive decrease in bone density and strength.
6.    Spinal deformities: The irregularities include scoliosis, a curving of the spine to the side; kyphosis, in which the normal curve of the upper back is severely rounded; lordosis, an abnormally accentuated arch in the lower back; back extension, a bending backward of the spine; and back flexion, in which the spine bends forward.
7.    Fibromyalgia is a chronic disorder characterized by widespread musculoskeletal pain, fatigue, and multiple “tender points,” particularly in the neck, spine, shoulders, and hips. Additional symptoms may include sleep disturbances, morning stiffness, and anxiety.
8.    Spondylitis refers to chronic back pain and stiffness caused by a severe infection to or inflammation of the spinal joints.
9.    Osteomyelitis  : Infection in the bones of the spine
10.    Ssacroiliitis : Inflammation in the sacroiliac joints.

Diagnosis
1.    History
2.    Physical examination
3.    X-ray imaging
4.    Discography
5.    Computerized tomography (CT)
6.    Magnetic resonance imaging (MRI)

Treatment of low back pain
1.    Trigger point release
2.    Myofascial release
3.    Spinal mobilizations
4.    McKenzie back regimen
5.    Spinal stretching & strengthening exercises
6.    Back school