Although strains are not restricted to athletes and can happen while doing everyday tasks, however, people who play sports are more at risk for developing a strain. It should also be noted that it is common for an injury to develop when there is a sudden increase in duration, intensity, or frequency of an activity.

Back strain occurs more in women than men and is more common after pregnancy. Lean people, those standing for long hours and those doing sedentary work in bad posture are prone to back strain. Back strain is also more common in people with excessive curving of the back, weak muscles (as in muscular dystrophies) and tight thigh muscles. Sportspersons who play sports involving lifting heavy weights, pushing and pulling are also prone to back strain.

Workers in certain fields are at risk of repetitive strains. Most occupational injuries are musculoskeletal disorders, and many of these are caused by cumulative trauma rather than a single event. Miners and poultry workers, for example, must make repeated motions which can cause tendon, muscular, and skeletal injuries.

People vary in their tendency to get MSDs. Gender is a factor with a higher rate in women than men. Obesity is also a factor, with overweight individuals having a higher risk of some MSDs, specifically lower back.

About 25% of people over the age of 50 experience knee pain from degenerative knee diseases.

There is a growing consensus that psychosocial factors are another cause of some MSDs. Some theories for this causal relationship found by many researchers include increased muscle tension, increased blood and fluid pressure, reduction of growth functions, pain sensitivity reduction, pupil dilation, body remaining at heightened state of sensitivity. Although research findings are inconsistent at this stage, some of the workplace stressors found to be associated with MSDs in the workplace include high job demands, low social support, and overall job strain. Researchers have consistently identified causal relationships between job dissatisfaction and MSDs. For example, improving job satisfaction can reduce 17-69 per cent of work-related back disorders and improving job control can reduce 37-84 per cent of work-related wrist disorders.

The diagnosis of mild back strain can be made with a medical history and physical examination. In case of more severe strains, an X-ray should be taken to rule out fracture and disc herniation. Back sprain is treated using analgesics such as ibuprofen, rest and use of ice packs. The patient can resume activities 24-48 hours after pain and swelling is reduced. It is not recommended to have prolonged immobilization or bed rest. If the pain does not subside in two weeks, additional treatment may be required.

Prevention of back strain is possible by adopting proper body mechanics while sitting, standing and lifting. Cessation of smoking, maintaining a healthy diet, exercise and normal weight is also good for preventing back strain.

In the United States, more than US $3 billion is spent each year on arthroscopic knee surgeries that are known to be ineffective in people with degenerative knee pain.

Repetitive strain injury (RSI) and associative trauma orders are umbrella terms used to refer to several discrete conditions that can be associated with repetitive tasks, forceful exertions, vibrations, mechanical compression, or sustained/awkward positions. Examples of conditions that may sometimes be attributed to such causes include edema, tendinosis (or less often tendinitis), carpal tunnel syndrome, cubital tunnel syndrome, De Quervain syndrome, thoracic outlet syndrome, intersection syndrome, golfer's elbow (medial epicondylitis), tennis elbow (lateral epicondylitis), trigger finger (so-called stenosing tenosynovitis), radial tunnel syndrome, ulnar tunnel syndrome, and focal dystonia.

Since the 1970s there has been a worldwide increase in RSIs of the arms, hands, neck, and shoulder attributed to the widespread use of typewriters/computers in the workplace that require long periods of repetitive motions in a fixed posture.

The most common causes of upper back pain are unknown but theorized to originate from muscular irritation, intervertebral discs, spinal facet joints, ribs or soft tissue (e.g. ligament/fascia) problems. Commonly intra-scapular pain is referred from the lower cervical spine. Contributing factors to injury include; lack of strength, poor posture, overuse injuries (such as repetitive motion), or a trauma (such as a car accident or sports injury). Often thoracic pain can be aggravated twisting, side bending and with prolonged bent spinal postures.

A compression fracture of the vertebra can also cause acute and/or chronic pain in the upper back. Trauma may cause a fracture, but in women over age 50 without significant trauma or someone known to have osteoporosis, a spontaneous vertebral compression fracture is possible.

Other, less common causes of thoracic back pain include a spinal disc herniation which often may have radicular pain (wrapping around the ribs associated with numbness and burning pain), spinal tumors and rib fractures may mimic thoracic pain/radicular pain. Other possible sources of referral pain into the thoracic region include visceral organs like: lungs, gallbladder, stomach, liver duodenum, pleura and cardiac.

Middle back pain has long been considered a "red flag" to alert healthcare professionals to the possibility of cancer (metastasis or spread to the spine). This is not a sensitive or specific phenomenon and can therefore not be relied upon in isolation.

Overall, the outcome for acute low back pain is positive. Pain and disability usually improve a great deal in the first six weeks, with complete recovery reported by 40 to 90%. In those who still have symptoms after six weeks, improvement is generally slower with only small gains up to one year. At one year, pain and disability levels are low to minimal in most people. Distress, previous low back pain, and job satisfaction are predictors of long-term outcome after an episode of acute pain. Certain psychological problems such as depression, or unhappiness due to loss of employment may prolong the episode of low back pain. Following a first episode of back pain, recurrences occur in more than half of people.

For persistent low back pain, the short-term outcome is also positive, with improvement in the first six weeks but very little improvement after that. At one year, those with chronic low back pain usually continue to have moderate pain and disability. People at higher risk of long-term disability include those with poor coping skills or with fear of activity (2.5 times more likely to have poor outcomes at one year), those with a poor ability to cope with pain, functional impairments, poor general health, or a significant psychiatric or psychological component to the pain (Waddell's signs).

A strain can occur as a result of improper body mechanics with any activity (e.g., contact sports, lifting heavy objects, overstretching) that can induce mechanical trauma or injury. Generally, the muscle or tendon overstretches and is placed under more physical stress than it can exert. Strains commonly result in a partial or complete tear of a tendon or muscle, or they can be severe in the form of a complete tendon rupture. The most common body location for strains to occur is in the foot, leg, or back.

- Acute strains are more closely associated with recent mechanical trauma or injury.

- Chronic strains typically result from repetitive movement of the muscles and tendons over a long period of time.

Degrees of Injury (as classified by the American College of Sports Medicine)

• First degree (mildest) – little tissue tearing; mild tenderness; pain with full range of motion.

• Second degree – torn muscle or tendon tissues; painful, limited motion; possibly some swelling or depression at the spot of the injury.

• Third degree (most severe) – limited or no movement; pain will be severe at first, but may be painless after the initial injury

Low back pain that lasts at least one day and limits activity is a common complaint. Globally, about 40% of people have LBP at some point in their lives, with estimates as high as 80% of people in the developed world. 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. Difficulty most often begins between 20 and 40 years of age. Low back pain is more common among people aged 4080years, with the overall number of individuals affected expected to increase as the population ages.

It is not clear whether men or women have higher rates of low back pain. A 2012 review reported a rate of 9.6% among males and 8.7% among females. Another 2012 review found a higher rate in females than males, which the reviewers felt was possibly due to greater rates of pains due to osteoporosis, menstruation, and pregnancy among women, or possibly because women were more willing to report pain than men. An estimated 70% of women experience back pain during pregnancy with the rate being higher the further along in pregnancy. Current smokers – and especially those who are adolescents – are more likely to have low back pain than former smokers, and former smokers are more likely to have low back pain than those who have never smoked.

Thoracic spinal pain was significantly associated with: concurrent musculoskeletal pain; growth and physical; lifestyle and social; backpack; postural; psychological; and environmental factors. Specific risk factors identified in adolescents included age (being older) and poorer mental health.

An overuse injury occurs when a certain activity is repeated frequently, and the body doesn't have enough time to recover in between occurrences. Some examples include bursitis and tendinitis.

Any type of injury that occurs to the body through sudden trauma, such as a fall, twist, or blow to the body. A few examples of this type of injury would be sprains, strains, and contusions.

"Any finger injury that is sustained by a young adolescent (12–16) should be seen by a physician and have x-rays performed. These skeletally immature athletes are very susceptible to developing debilitating joint arthritis later in adulthood."

The condition is called "Golfer's Elbow" because in making a golf swing this tendon is stressed, especially if a non-overlapping (baseball style) grip is used; many people, however, who develop the condition have never handled a golf club. It is also sometimes called "Pitcher's Elbow" due to the same tendon being stressed by the throwing of objects such as a baseball, but this usage is much less frequent. Other names are "Climber's Elbow" and "Little League Elbow": all of the flexors of the fingers and the pronators of the forearm insert at the medial epicondyle of the humerus to include: pronator teres, flexor carpi radialis, flexor carpi ulnaris, flexor digitorum superficialis, and palmaris longus; making this the most common elbow injury for rock climbers, whose sport is very grip intensive. The pain is normally caused due to stress on the tendon as a result of the large amount of grip exerted by the digits and torsion of the wrist which is caused by the use and action of the cluster of muscles on the condyle of the ulna.

Epicondylitis is much more common on the lateral side of the elbow (tennis elbow), rather than the medial side. In most cases, its onset is gradual and symptoms often persist for weeks before patients seek care. In golfer's elbow, pain at the medial epicondyle is aggravated by resisted wrist flexion and pronation, which is used to aid diagnosis. On the other hand, tennis elbow is indicated by the presence of lateral epicondylar pain precipitated by resisted wrist extension. Although the condition is poorly understood at a cellular and molecular level, there are hypotheses that point to apoptosis and autophagic cell death as causes of chronic lateral epicondylitis. The cell death may decrease the muscle density and cause a snowball effect in muscle weakness - this susceptibility can compromise a muscle's ability to maintain its integrity. So athletes, like pitchers, must work on preventing this cell death via flexibility training and other preventive measures.

In terms of overuse injuries a British study found that:

- 40 percent occurred in the fingers

- 16 percent in the shoulders

- 12 percent in the elbows

- 5 percent were the knees

- 5 percent back

- 4 percent wrists

One injury that tend to be very common among climbers is Carpal tunnel syndrome. It is found in about 25% of climbers.

Like many other joints throughout the human body, facets can experience natural degeneration from constant use. Over time, the cartilage within the joints can naturally begin to wear out, allowing it to become thin or disappear entirely which, in turn, allows the conjoining vertebrae to rub directly against one another with little or no lubricant or separation. A result of this rubbing is often swelling, inflammation or other painful symptoms.

Over time, the body will naturally respond to the instability within the spine by developing bone spurs, thickened ligaments or even cysts that can press up against or pinch the sensitive nerve roots exiting the spinal column.

While primarily caused through natural wear and tear, advanced facet syndrome can also occur as a result of injury to the spine, degenerative disease or lifestyle choices. These causes can include:

- An unexpected, traumatic event such as a car accident, significant fall or high impact sports injury.

- Osteoarthritis

- Spondylolisthesis

- Obesity

- Smoking

- Malnutrition

- Lack of physical exercise or daily activity

The cause of de Quervain's disease is not established. Evidence regarding a possible relation with occupational risk factors is debated. A systematic review of potential risk factors discussed in the literature did not find any evidence of a causal relationship with occupational factors. However, researchers in France found personal and work-related factors were associated with de Quervain's disease in the working population; wrist bending and movements associated with the twisting or driving of screws were the most significant of the work-related factors. Proponents of the view that De Quervain syndrome is a repetitive strain injury consider postures where the thumb is held in abduction and extension to be predisposing factors. Workers who perform rapid repetitive activities involving pinching, grasping, pulling or pushing have been considered at increased risk. Specific activities that have been postulated as potential risk factors include intensive computer mouse use, trackball use, and typing, as well as some pastimes, including bowling, golf, fly-fishing, piano-playing, sewing, and knitting.

Women are affected more often than men. The syndrome commonly occurs during and after pregnancy. Contributory factors may include hormonal changes, fluid retention and—more debatably—lifting.

55% of facet syndrome cases occur in cervical vertebrae, and 31% in lumbar. Facet syndrome can progress to spinal osteoarthritis, which is known as spondylosis. Pathology of the C1-C2 (atlantoaxial) joint, the most mobile of all vertebral segments, accounts for 4% of all spondylosis.

A side strain is a muscle strain caused by tearing of the transversalis fascia or the internal oblique muscle. When this occurs, stretching the muscle will be severely painful, making it difficult to move the arm, and the strain may later be marked by swelling or bruising.

The strain usually occurs due to the internal oblique muscle contracting suddenly from a stretched position. It may happen suddenly, or over time from regular repetitive activity. It is common in cricket players, and occurs on the opposite side of the arm that is used for bowling. The injury has also been reported in rowing, baseball and ice hockey. The preferred treatment for a side strain is regular rest and inactivity on the affected muscle. With appropriate rest, regular activity on the muscle can occur between 4 and 6 weeks, though it may take longer.

The consequences of whiplash range from mild pain for a few days (which is the case for most people), to severe disability. It seems that around 50% will have some remaining symptoms.

Alterations in resting state cerebral blood flow have been demonstrated in patients with chronic pain after whiplash injury. There is evidence for persistent inflammation in the neck in patients with chronic pain after whiplash injury.

There has long been a proposed link between whiplash injuries and the development of temporomandibular joint dysfunction (TMD). A recent review concluded that although there are contradictions in the literature, overall there is moderate evidence that TMD can occasionally follow whiplash injury, and that the incidence of this occurrence is low to moderate.

There are many causes of TOS. The most frequent cause is trauma, either sudden (as in a clavicle fracture caused by a car accident), or repetitive (as in a legal secretary who works with his/her hands, wrists, and arms at a fast paced desk station with non-ergonomic posture for many years). TOS is also found in certain occupations involving lots of lifting of the arms and repetitive use of the wrists and arms.

One cause of arterial compression is trauma, and a recent case involving fracture of the clavicle has been reported.

The two groups of people most likely to develop TOS are those suffering from neck injuries due to traffic accidents and those who use computers in non-ergonomic postures for extended periods of time. TOS is frequently a repetitive stress injury (RSI) caused by certain types of work environments. Other groups which may develop TOS are athletes who frequently raise their arms above the head (such as swimmers, volleyball players, dancers, badminton players, baseball pitchers, and weightlifters), rock climbers, electricians who work long hours with their hands above their heads, and some musicians.