A muscle cramp is a sudden and involuntary contraction of one or more of your muscles. If you've ever been awakened in the night or stopped in your tracks by a sudden charley horse, you know that muscle cramps can cause excruciating pain. Though generally harmless, muscle cramps can make it temporarily impossible to use the affected muscle.

Long periods of exercise or physical labor, particularly in hot weather, may lead to muscle cramps. Some medications and certain medical conditions also may cause muscle cramps. You can usually treat muscle cramps at home with self-care measures.

Source: http://www.mayoclinic.com

Most muscle cramps develop in the leg muscles, particularly the muscles in the calf. In addition to the sudden, sharp pain, you may also be able to feel or see a hard lump of muscle tissue beneath your skin.

When to see a doctor

Muscle cramps usually disappear on their own and are rarely serious enough to require medical care. However, see your doctor if your cramps:

• Cause severe discomfort
• Are associated with leg swelling, redness or skin changes
• Are associated with muscle weakness
• Happen frequently
• Don't improve with self-care
• Aren't associated with an obvious cause, such as strenuous exercise

Source: http://www.mayoclinic.com

Overuse of a muscle, dehydration, muscle strain or simply holding a position for a prolonged period of time may result in a muscle cramp. In many cases, however, the exact cause of a muscle cramp isn't known.

Although most muscle cramps are harmless, some may be related to an underlying medical condition, such as:

• 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 usually go away soon after you stop exercising.
• 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 employ when pushing a shopping cart ahead of you — may improve or delay the onset of your symptoms.
• Mineral depletion. Too little potassium, calcium or magnesium in your diet can contribute to leg cramps. Diuretics — medications often prescribed for high blood pressure — may also deplete these minerals.

Source: http://www.mayoclinic.com

These steps may help prevent cramps:

• Avoid dehydration. Drink plenty of liquids every day. 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. 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. Light exercise, such as riding a stationary bicycle for a few minutes before bedtime, also may help prevent cramps while you're sleeping.

Source: http://www.mayoclinic.com

Taking vitamin B complex supplements is suggested by some to help manage leg cramps. However, more research is needed to confirm this benefit.

Source: http://www.mayoclinic.com

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, sit on the floor or in a chair with your affected leg extended. Try pulling the top of your foot on the affected side toward your head while your leg remains 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 heat or cold. Use a warm towel or heating pad on tense or tight muscles. Taking a warm bath or directing the stream of a hot shower onto the cramped muscle also can help. Alternatively, massaging the cramped muscle with ice may relieve pain.

Source: http://www.mayoclinic.com

Factors that may increase your risk of muscle cramps include:

• Age. Older people lose muscle mass, so the remaining muscle may get overstressed more easily. This may increase the risk for muscle cramps.
• Dehydration. Athletes who become fatigued and dehydrated while participating in warm-weather sports frequently develop muscle cramps.
• Pregnancy. Muscle cramps also are more common during pregnancy.
• Medical conditions. You may be at higher risk of muscle cramps if you have diabetes, or nerve, liver or thyroid disorders.

Source: http://www.mayoclinic.com