What are muscle cramps?

A muscle cramp is a sudden contraction of one or more of your muscles. The result can be intense pain and an inability to use the affected muscles.

Common causes of leg cramps in athletes are overuse and dehydration during sports played in warm weather. Injury, muscle strain or staying in the same position also may cause muscle cramps.

Other causes of muscle cramps may include circulatory or nerve problems. Some muscle cramps occur during rest. A common variety of muscle cramp occurs in your calf muscles or toes during sleep.

You can usually treat muscle cramps with self-care measures.

Signs and Symptoms

Signs and symptoms of a muscle cramp include:

> Sudden and sharp muscle pain (spasm, contraction), often in your legs
> A hard lump of muscle tissue that you can feel or is visible beneath your skin

Types

"True" cramps

"True" cramps involve part or all of a single muscle or a group of muscles that generally act together, such as the muscles that flex several adjacent fingers. Most authorities agree that "true" cramps are caused by hyperexcitability of the nerves that stimulate the muscles. They are overwhelmingly the most common type of skeletal muscle cramps. "True" cramps can occur in a variety of circumstances as follows:

Injury

Persistent muscle spasm may occur as a protective mechanism following an injury, such as a broken bone. In this instance, the spasm tends to minimize movement and stabilize the area of injury. Injury of the muscle alone may cause the muscle to spasm.

Contractures

Contractures result when the muscles are unable to relax. The constant spasms are caused by a depletion of adenosine triphosphate (ATP), an energy chemical within the cell. This prevents muscle fiber relaxation. The nerves are inactive in this form of muscle spasm.

Contractures can be inherited (for example, McArdle's disease, which is a defect of the breakdown of glycogen to sugar within the muscle cell) or acquired (for example, hyperthyroid myopathy, which is a muscle disease that is associated with an overactive thyroid). Cramps of this category are uncommon.

Dystonic cramps

The final category is dystonic cramps, in which muscles that are not needed for the intended movement are stimulated to contract. Muscles that are affected by this type of cramping include those that ordinarily work in the opposite direction of the intended movement, and/or others that exaggerate the movement. Some dystonic cramps usually affect small groups of muscles (eyelids, jaws, neck, larynx, etc.). The hands and arms may be affected during the performance of repetitive activities such as those associated with handwriting (writer's cramp), typing, playing certain musical instruments, and many others. Each of these repetitive activities may also produce "true" cramps from muscle fatigue. Dystonic cramps are not as common as "true" cramps.

Causes

Overuse of a muscle, dehydration, injury, muscle strain or simply holding a position for prolonged periods of time may result in a muscle cramp. Athletes who become fatigued and dehydrated while participating in warm-weather sports frequently develop muscle cramps. Muscle cramps in your legs also can result from:

> Inadequate blood supply. Narrowing of the arteries that deliver blood to your legs (arteriosclerosis of the extremities) can produce cramp-like pain in your legs and feet while you're exercising. These cramps go away within a minute or two after you stop exercising and stand still.
> Nerve compression. Compression of nerves in your spine (lumbar stenosis) also can produce cramp-like pain in your legs. The pain usually worsens the longer you walk. Walking in a slightly flexed position — such as you would when pushing a shopping cart ahead of you — may improve your symptoms.
> Mineral depletion. Too little potassium, calcium or magnesium in your diet can contribute to leg cramps. Some diuretic medications prescribed for high blood pressure cause loss of potassium.
> Several vitamin deficiency states may directly or indirectly lead to muscle cramps. These include deficiencies of thiamine (B1), pantothenic acid (B5), and pyridoxine (B6). The role of deficiency of these vitamins in causing cramps is unknown.

Muscle cramps are also part of certain conditions such as nerve, thyroid or hormone disorders, diabetes, hypoglycemia and anemia.

Treatment

If you have a cramp, these actions may provide relief:

> Stretch and massage. Stretch the cramped muscle and gently rub it to help it relax. For a calf cramp, put your weight on your cramped leg and bend your knee slightly. If you're unable to stand, try pulling the top of your foot on the affected side toward your head while your leg is in a straightened position. This will also help ease a back thigh (hamstring) cramp. For a front thigh (quadriceps) cramp, use a chair to steady yourself and try pulling your foot on the affected side up toward your buttock.
> Apply cold or heat. Use a cold pack to relax tense muscles. Use a warm towel or heating pad later if you have pain or tenderness, or take a hot bath.

Prevention

These steps may help prevent cramps:

> Avoid dehydration. Drink plenty of liquids every day, generally at least six glasses of water or other beverages daily. The exact amount depends on what you eat, your sex, your level of activity, the weather, your health, your age and any medications you may be taking. Fluids help your muscles contract and relax and keep muscle cells hydrated and less irritable. Drink fluids before any exercise activity. During the activity, replenish fluids at regular intervals, and continue drinking water or other fluids after you're finished.
> Stretch your muscles. Stretch before and after you use any muscle for an extended period. If you tend to have leg cramps at night, stretch before bedtime.



References:
1. mayoclinic.com
2. medicinenet.com

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