Low back pain (LBP) or painful low back is just what it sounds like: pain in the low spine and/or lower back region. The low back consists of muscle, nerve, bone and connecting tissues. The spine includes the spinal cord (the main nerve cable between the brain and the rest of the body), its bony protection (the vertebral bones or vertebrae), and the ligaments and muscles that hold everything in place. The low back also includes the large back and buttock muscles, plus the pelvic bones.
Low back pain may feel a number of ways: sore, tight, or sharp sensations are common. Clear causes are hard to identify because so many factors contribute to low back pain: external factors like overuse or exertion, and/or internal factors like genetic weakness of certain tissues, may determine how back pain evolves. Common causes also vary by age. LBP is relatively rare in the very young, whereas injury dominates middle age, and 
degeneration (arthritis) manifests with more advanced age.
Low back pain is the second most frequent reason to visit a physician for a chronic condition. [1,2,3,4] Chronic low back pain is the most common cause of disability in Americans younger than 45 years.
X
1 Anderssen GBJ. Frymoyer JW (ed.). The epidemiology of spinal disorders, in The Adult Spine: Principles and Practice. New York: Raven Press; 1997:93-141.
2 Cunningham LS, Kelsey JL. Epidemiology of musculoskeletal impairments and associated disability. Am J Public Health. Jun 1984;74(6):574-9. [Medline].
3 National Center for Health Statistics (1977):. Limitations of activity due to chronic conditions, United States. Series 10, No.111. 1974..
4 National Center for Health Statistics (1975):. Physician visits, volume and interval since last visit, United States. 1971. Series 10, No.97.
5 Nachemson Al, Waddell G, Norland AL. Nachemson AL, Jonsson E (eds.). Epidemiology of Neck and Low Back Pain, in. Neck and Back Pain: The scientific evidence of causes, diagnoses, and treatment. Philadelphia: Lippincott Williams & Wilkins; 2000:165-187.
6 Mayer TG, Gatchel RJ. Functional restoration for spinal disorders: The sports medicine approach. Philadelphia: Lea & Febiger; 1988.
7 Biering-Sorenson F. Low back trouble and a general population of 30-, 40-, 50-, and 60–year-old men and women. Dan Med Bull. 1982;29:289-99.
8 Damkot DK, Pope MH, Lord J, Frymoyer JW. The relationship between work history, work environment and low-back pain in men. Spine (Phila Pa 1976). May-Jun 1984;9(4):395-9. [Medline].
9 “Acupuncture Energetics: A Clinical Approach for Physicians”. Joseph M. Helms. Medical Acupuncture Publishers; 1st Edition. (1995)
10 “Foundations of Chinese Medicine: A Comprehensive Text for Acupuncturists and Herbalists”. Giovanni Maciocia. Churchill Livingstone; 2 Edition (July, 2005).
11 “Travell & Simons’ Myofascial Pain and Dysfunction: The Trigger Point Manual”. David G. Simons, Janet G. Travell, Lois S. Simons, Barbara D. Cummings. Lippincott Williams & Wilkins; 2 edition (1998)
12 “Traditional Chinese Medicine Cupping Therapy”. Ilkay Chirali. Churchill & Livinstone; 2 editioin (2007)
13 Argoff CE, Wheeler AH. Backonja MM, ed. Spinal and radicular pain syndromes. Philadelphia, WB Saunders: Neurologic Clinics; 1998:833-45.
14 Wheeler AH. Diagnosis and management of low back pain and sciatica. Am Fam Physician. Oct 1995;52(5):1333-41, 1347-8.
15 Wheeler AH, Murrey DB. Spinal pain: pathogenesis, evolutionary mechanisms, and management, in Pappagallo M (ed). The neurological basis of pain. New York: McGraw-Hill; 2005:421-52.
16 “Essentials of Musk Care”
17 Mooney V. Presidential address. International Society for the Study of the Lumbar Spine. Dallas, 1986. Where is the pain coming from?. Spine (Phila Pa 1976). Oct 1987;12(8):754-9. .
18 Waddell G. 1987 Volvo award in clinical sciences. A new clinical model for the treatment of low-back pain. Spine (Phila Pa 1976). Sep 1987;12(7):632-44.
19 Frymoyer JW. Back pain and sciatica. N Engl J Med. Feb 4 1988;318(5):291-300.
20 Argoff CE, Wheeler AH. Backonja MM, ed. Spinal and radicular pain syndromes. Philadelphia, WB Saunders: Neurologic Clinics; 1998:833-45.
21 Mooney V. Presidential address. International Society for the Study of the Lumbar Spine. Dallas, 1986. Where is the pain coming from?. Spine (Phila Pa 1976). Oct 1987;12(8):754-9.
22 Wheeler AH, Hanley EN Jr. Nonoperative treatment for low back pain. Rest to restoration. Spine (Phila Pa 1976). Feb 1 1995;20(3):375-8. [Medline].
23 Jensen MC, Brant-Zawadzki MN, Obuchowski N, Modic MT, Malkasian D, Ross JS. Magnetic resonance imaging of the lumbar spine in people without back pain. N Engl J Med. Jul 14 1994;331(2):69-73