To understand what muscle strains are it is important to understand the anatomy of muscle. The musculoskeletal system is made up of muscles and skeletons. Muscles are the soft tissues composed of specialized cells called muscle fibers that attach to the skeletal system’s bones. There are up to 700 muscles that attach to the bony skeleton.
There are three types of muscles- smooth, skeletal (striated), and cardiac muscle. The skeletal muscle is attached to the bones and makes skeletal movement possible. The basic unit of these muscles is called muscle fiber and are striated. These muscles are controlled voluntarily (via the peripheral nervous system).
The smooth muscle, also known as the visceral muscle, is the muscles covering the walls of internal organs like the uterus, gastrointestinal tracts, and blood vessels. These muscles act involuntarily (via the autonomic nervous system).
The cardiac muscle, just as its name implies, is found in the walls of the heart. It is striated, just like the skeletal system. However, its contraction is rhythmical and involuntary. That means the autonomic nervous system controls it.
This article will discuss exclusively a common complication of the muscle- muscle strain, pathophysiology and etiology, who is usually affected, clinical presentation, diagnosis, and treatment.
Muscle strain: Overview and epidemiology
Muscle strain, also commonly called muscle tear or muscle pull is damage to a muscle or surrounding tendons.
Sometimes, during physical activity such as sports or heavy lifting, you put undue pressure on your muscles. This can cause damage to the muscle fibers actively involved in the movement.
Muscle strain can present as part or all the muscle fibers. Tendons attached to the muscle might be affected as well. The muscle tear can also cause damage to small blood vessels supplying the muscle, thus causing localized bleeding and bruising. When nerve endings in the area are affected, it will cause pain and irritation.
Muscle strains are injuries that are very much prevalent in amateur and professional sports. According to an article on ResearchGate, muscle strains, particularly those that affect the hamstring muscles, form the most frequent injury type in soccer and Australian football.
Hamstring strain has been cited as the most common muscle strain. It is prevalent amongst athletes involved in popular sports events that have to do with kicking and high-speed sprinting, e.g., football (soccer) and rugby, cross-country skiing, track and field, waterskiing, cricket, and bull riding.
Pathophysiology and etiology of muscle strain
Muscle strains typically occur due to over-training, rapid stretching, or improper training, leading to eccentric muscle contraction. Eccentric contraction is when muscle length increases as tension are produced.
Acute muscle strain is a sudden and unexpected muscle tearing and can be due to poor flexibility, overexertion, fatigue, poor conditioning, and improper warm-up before physical activity.
Muscle strains occur around the musculotendinous junction as a result of forceful or rapid contraction. They can be categorized into three degrees:
- Grade I strain: This is a mild strain that involves only a few stretched or torn muscles. Even though the affected muscle is painful and tender, it still has its normal strength.
- Grade II strain: This is a moderate strain and has more muscle fibers injured than the grade I strain. Pain and tenderness are more severe than grade I strain, and there is often a noticeable loss of muscle strain with mild swelling.
- Grade III strain: Here, the muscles are badly injured as they are torn into separate pieces or torn away from the attaching tendon. This type of tear sometimes produces a ‘pop’ sensation and comes with intense pain, tenderness, swelling, and discoloration. This type of muscle injury is quite serious and can cause a complete loss of muscle function.
Healing of the damaged muscle fibers follows a repair process- destruction, repair, and remodeling. After the tearing and necrosis of myofibrils, there will be a formation of hematoma and inflammatory cells. This would be followed by regeneration of the myofibrils, neural growth, and production of connective tissue scar.
When the myofibrils have fully regenerated, there will be a reorganization of the scar tissue, full recovery of muscle function, and contractibility.
Clinical presentation and diagnosis of muscle strain
Muscle strain presents with symptoms such as pain even while at rest, muscle or tendon weakness, inability to move or use the affected muscle, bruising, swelling, and redness due to the injury.
The strain might also be accompanied by muscle cramps, spasm stiffness, soreness, and progressive pain, which worsens with movement.
To diagnose muscle strain, physicians first perform a physical examination and then ask for patient symptom history. There might also be a need to order imaging tests such as X-rays to ensure that a bone was not also broken.
Doctors during diagnosis also categorize injury based on the injury grade (Grade I to III) as mentioned earlier.
Muscle strain treatment
Muscle strain is usually not life-threatening and doesn’t take long to resolve (depending on the degree). Most times, they can be treated at home. A step that has shown to be effective in muscle strain treatment is RICE – Rest, Ice, Compression, and Elevation.
- Rest: It might help patients to rest their muscles and avoid using it for a few days, especially if they feel pain with movement. However, the patient shouldn’t rest for too long as that might cause muscle weakness. It is best to slowly start using the muscle after about two days.
- Ice: Applying ice immediately after injury to the affected muscle minimizes swelling. This should be done for about 20 minutes, repeatedly using an ice pack.
- Compression: Here, the patient would wrap the affected area with an elastic bandage to reduce swelling. The bandage shouldn’t be too tight so as to maintain blood circulation.
- Elevation: The patient should keep the injured muscle raised high above the heart level whenever possible. This is to reduce swelling and support blood flow towards the heart.
Other methods that have shown to be effective in treating muscle strain include:
- using over-the-counter anti-inflammatory medicines such as acetaminophen and ibuprofen.
- Applying heat after about three days.
- Engaging in recovery exercises and stretching before exercising.