Your spinal discs are located between adjacent vertebrae and serve as shock-absorbing cushions. For a combination of reasons—including the natural process of aging, trauma to the spine, weight gain, smoking, and repetitive stress to the spine (for example, sitting for prolonged periods of time or lifting heavy objects)—the discs begin to deteriorate over time, making them more prone to bulging or protruding outward (called a bulging or slipped disc).

Bony encroachment: Any condition that results in movement or growth of the vertebrae of the lumbar spine can limit the space (encroachment) for the adjacent spinal cord and nerves. Causes of bony encroachment of the spinal nerves include foraminal narrowing (narrowing of the portal through which the spinal nerve passes from the spinal column, out of the spinal canal to the body, commonly as a result of arthritis), spondylolisthesis (slippage of one vertebra relative to another), and spinal stenosis (compression of the nerve roots or spinal cord by bony spurs or other soft tissues in the spinal canal). Spinal-nerve compression in these conditions can lead to sciatica pain that radiates down the lower extremities. Spinal stenosis can cause lower-extremity pains that worsen with walking and are relieved by resting (mimicking the pains of poor circulation). Treatment of these afflictions varies, depending on their severity, and ranges from rest and exercises to epidural cortisone injections and surgical decompression by removing the bone that is compressing the nervous tissue.

Using the wrong form or overexerting yourself can strain muscles or tendons in your back, or sprain one of your ligaments, according to the Cleveland Clinic. That essentially means those components have been twisted, stretched, or torn. These kinds of injuries can present as abrupt pain that worsens with activity, muscles cramps or spasms, and stiffness or limited movement.
Lumbar strain (acute, chronic): A lumbar strain is a stretch injury to the ligaments, tendons, and/or muscles of the low back. The stretching incident results in microscopic tears of varying degrees in these tissues. Lumbar strain is considered one of the most common causes of low back pain. The injury can occur because of overuse, improper use, or trauma. Soft-tissue injury is commonly classified as "acute" if it has been present for days to weeks. If the strain lasts longer than three months, it is referred to as "chronic." Lumbar strain most often occurs in people in their 40s, but it can happen at any age. The condition is characterized by localized discomfort in the low back area with onset after an event that mechanically stressed the lumbar tissues. The severity of the injury ranges from mild to severe, depending on the degree of strain and resulting spasm of the muscles of the low back. The diagnosis of lumbar strain is based on the history of injury, the location of the pain, and exclusion of nervous system injury. Usually, X-ray testing is only helpful to exclude bone abnormalities.
There is a significant overlap of nerve supply to many of the discs, muscles, ligaments, and other spinal structures, and it can be difficult for the brain to accurately sense which is the cause of the pain. For example, a degenerated or torn lumbar disc can feel the same as a pulled muscle – both creating inflammation and painful muscle spasm in the same area. Muscles and ligaments heal rapidly, while a torn disc may or may not. The time course of pain helps determine the cause.
Quadratus lumborum muscle trigger points can cause right-sided low back pain. The QL muscle is a paired muscle that is quadrilateral in shape. It runs from the rear crest of the pelvis to the last rib and the transverse processes of the lumbar vertebrae, which are situated on the sides of the vertebra bones. Acting by itself, the QL helps the spine bend laterally or to the side. When both QL muscles act together, they help depress or lower the rib cage. According to the American Academy of Family Physicians, or AAFP, the QL muscles, along with other muscles that help maintain the body's posture, are a common location for myofascial trigger points, or MFTPs--hyperirritable nodules or knots within a tight band of muscle. MFTPs can often be found in the right QL, left QL or both QLs, and may be painful without provocation or when they are pressed or squeezed. The AAFP notes that people who have MFTPs, including MFTPs in the lower aspect of the right QL, frequently report regional persistent pain that causes a reduced range of motion in that muscle.

If you have large breasts, you’re carrying more weight on the front of your body, which can throw off the curve of your spine and lead to upper back problems. Wearing a bra that provides proper support can help keep the weight closer to your body and help you maintain your posture, Smith says. You should be able to draw a straight line from the top of your head down to your heels, and a supportive bra will help.
“The Pain Perplex,” a chapter in the book Complications, by Atul Gawande. Gawande’s entire book is worth reading, but his chapter on pain physiology is certainly the best summary of the subject I have ever read, and a terrific reminder that good writing for a general audience can be just as illuminating for professionals. Anyone struggling with a pain problem should buy the book for this chapter alone, though you are likely to enjoy the whole thing. Much of the chapter focuses on one of the most interesting stories of low back pain I’ve read, and it is a responsible and rational account — although Gawande, like most doctors, seems to be unaware of the clinical significance, or even existence, of myofascial trigger points.
Spinal disk disease occurs when the nucleus pulposus, a gel-like material in the inner core of the vertebral disc, ruptures.[18] Rupturing of the nucleus pulposus can lead to compression of nerve roots. Symptoms may be unilateral or bilateral, and correlate to the region of the spine affected. The most common region for spinal disk disease is at L4-L5 or L5-S1. The risk for lumbar disc disease is increased in overweight individuals due to the increased compressive force on the nucleus pulposus.[18]
Antidepressants may be effective for treating chronic pain associated with symptoms of depression, but they have a risk of side effects.[13] Although the antiseizure drugs gabapentin, pregabalin, and topiramate are sometimes used for chronic low back pain evidence does not support a benefit.[79] Systemic oral steroids have not been shown to be useful in low back pain.[1][13] Facet joint injections and steroid injections into the discs have not been found to be effective in those with persistent, non-radiating pain; however, they may be considered for those with persistent sciatic pain.[80] Epidural corticosteroid injections provide a slight and questionable short-term improvement in those with sciatica but are of no long term benefit.[81] There are also concerns of potential side effects.[82]
Testimonials on health care websites reek of quackery, so publishing them has always made me a bit queasy. But my testimonials are mostly about the quality of the information I’m selling, and I hope that makes all the difference. So here’s some highlights from the kind words I’ve received over the years … plus some of the common criticisms I receive, at the end. These are all genuine testimonials, mostly received by email. In many cases I withold or change names and identifying details.
In between your vertebrae are rubbery cushions called spinal discs. These discs, which act as shock absorbers, are a little bit like jelly donuts. They have a softer inside with a tougher exterior. There are also a number of ligaments attached to your spine, connecting those stacking vertebrae to each other and to other bones. Beyond that, there are tendons attaching bones to surrounding muscles. Then there are the muscles of your back themselves.
All material herein is provided for information only and may not be construed as personal medical advice. No action should be taken based solely on the contents of this information; instead, readers should consult appropriate health professionals on any matter relating to their health and well-being. The publisher is not a licensed medical care provider. The information is provided with the understanding that the publisher is not engaged in the practice of medicine or any other health-care profession and does not enter into a health-care practitioner/patient relationship with its readers. The publisher is not responsible for errors or omissions.
Pain is generally an unpleasant feeling in response to an event that either damages or can potentially damage the body's tissues. There are four main steps in the process of feeling pain: transduction, transmission, perception, and modulation.[12] The nerve cells that detect pain have cell bodies located in the dorsal root ganglia and fibers that transmit these signals to the spinal cord.[33] The process of pain sensation starts when the pain-causing event triggers the endings of appropriate sensory nerve cells. This type of cell converts the event into an electrical signal by transduction. Several different types of nerve fibers carry out the transmission of the electrical signal from the transducing cell to the posterior horn of spinal cord, from there to the brain stem, and then from the brain stem to the various parts of the brain such as the thalamus and the limbic system. In the brain, the pain signals are processed and given context in the process of pain perception. Through modulation, the brain can modify the sending of further nerve impulses by decreasing or increasing the release of neurotransmitters.[12]
Disc degeneration remains a key cause of chronic low back pain and the pain often persists despite surgery. NIH-funded basic science and preclinical studies are investigating molecular-level mechanisms that cause discs in the spine to degenerate, as well as protective mechanisms involved in disc remodeling that may diminish with advancing age. Such studies may help identify future therapeutic strategies to block degenerative mechanisms or promote remodeling processes. NIH also is funding early research on stem cell approaches to promote disc regeneration and rejuvenate cells of the nucleus pulposus, the jelly-like substance in the center of intervertebral discs that loses water content as people age.
Low back pain can be caused by tumors, either benign or malignant, that originate in the bone of the spine or pelvis and spinal cord (primary tumors) and those which originate elsewhere and spread to these areas (metastatic tumors). Symptoms range from localized pain to radiating severe pain and loss of nerve and muscle function (even incontinence of urine and stool) depending on whether or not the tumors affect the nervous tissue. Tumors of these areas are detected using imaging tests, such as plain X-rays, nuclear bone scanning, and CAT and MRI scanning.
Low back pain can cause a wide variety of symptoms and signs depending on the precise cause of the back pain as reviewed above. Symptoms that can be associated with low back pain include numbness and/or tingling of the lower extremities, incontinence of urine or stool, inability to walk without worsening pain, lower extremity weakness, atrophy (decreased in size) of the lower extremity muscles, rash, fever, chills, weight loss, abdominal pains, burning on urination, dizziness, joint pain, and fatigue.

^ Paige, Neil M.; Miake-Lye, Isomi M.; Booth, Marika Suttorp; Beroes, Jessica M.; Mardian, Aram S.; Dougherty, Paul; Branson, Richard; Tang, Baron; Morton, Sally C.; Shekelle, Paul G. (11 April 2017). "Association of Spinal Manipulative Therapy With Clinical Benefit and Harm for Acute Low Back Pain". JAMA. 317 (14): 1451–1460. doi:10.1001/jama.2017.3086. PMC 5470352. PMID 28399251.

Infection of the discs (septic discitis) and bone (osteomyelitis) is extremely rare. These conditions lead to localized pain associated with fever. The bacteria found when these tissues are tested with laboratory cultures include Staphylococcus aureus and Mycobacterium tuberculosis (TB bacteria). TB infection in the spine is called Pott's disease. These are each very serious conditions requiring long courses of antibiotics. The sacroiliac joints rarely become infected with bacteria. Brucellosis is a bacterial infection that can involve the sacroiliac joints and is usually transmitted in raw goat's milk.
Arthritis: The spondyloarthropathies are inflammatory types of arthritis that can affect the lower back and sacroiliac joints. Examples of spondyloarthropathies include reactive arthritis (Reiter's disease), ankylosing spondylitis, psoriatic arthritis, and the arthritis of inflammatory bowel disease. Each of these diseases can lead to low back pain and stiffness, which is typically worse in the morning. These conditions usually begin in the second and third decades of life. They are treated with medications directed toward decreasing the inflammation. Newer biologic medications have been greatly successful in both quieting the disease and stopping its progression.

Low back pain that lasts at least one day and limits activity is a common complaint.[7] Globally, about 40% of people have LBP at some point in their lives,[7] with estimates as high as 80% of people in the developed world.[22] Approximately 9 to 12% of people (632 million) have LBP at any given point in time, and nearly one quarter (23.2%) report having it at some point over any one-month period.[7][8] Difficulty most often begins between 20 and 40 years of age.[1] Low back pain is more common among people aged 40–80 years, with the overall number of individuals affected expected to increase as the population ages.[7]

For example, rupture of the main artery in the abdomen (called a ruptured splenic artery aneurysm) can be a very serious cause of sharp back pain. Also, kidney infection (pyelonephritis) and an infection of the lining of the lungs and chest (pleurisy) can mimic back pain. In these cases, treatment of the underlying cause will usually resolve the back pain.
Biomechanical factors of pregnancy shown to be associated with back pain include increased curvature of the lower back, or lumbar lordosis, to support the added weight on the abdomen.[61] Also, a hormone called relaxin is released during pregnancy that softens the structural tissues in the pelvis and lower back to prepare for vaginal delivery. This softening and increased flexibility of the ligaments and joints in the lower back can result in pain.[61] Back pain in pregnancy is often accompanied by radicular symptoms, suggested to be caused by the fetus pressing on the sacral plexus and lumbar plexus in the pelvis.[61][59]
Bone scans are used to detect and monitor infection, fracture, or disorders in the bone. A small amount of radioactive material is injected into the bloodstream and will collect in the bones, particularly in areas with some abnormality. Scanner-generated images can be used to identify specific areas of irregular bone metabolism or abnormal blood flow, as well as to measure levels of joint disease.