Cramp Defined: Cramps are unpleasant, often painful sensations caused by muscle contraction or over shortening. Common causes of skeletal muscle cramps include muscle fatigue, low sodium, and low potassium.
Causes of Cramps:Causes of cramping include hyperflexion, hypoxia, exposure to large changes in temperature, dehydration, or low blood salt. Muscle cramps may also be a symptom or complication of pregnancy, kidney disease, thyroid disease, hypokalemia, hypomagnesemia or hypocalcemia (as conditions), restless-leg syndrome, varicose veins, and multiple sclerosis.
Electrolyte disturbance may cause cramping and muscle tetany, particularly hypokalaemia and hypocalcaemia. This disturbance arises as the body loses large amounts of interstitial fluid through sweat. This interstitial fluid comprises mostly water and table salt (sodium chloride). The loss of osmotically active particles outside of muscle cells leads to a disturbance of the osmotic balance and therefore shrinking of muscle cells, as these contain more osmotically active particles. This causes the calcium pump between the muscle lumen and sarcoplasmic reticulum to short circuit; the calcium ions remain bound to the troponin, continuing muscle contraction.
As early as 1965, researchers observed that leg cramps and restless-leg syndrome result from excess insulin, sometimes called hyperinsulinemia. Hypoglycemia and reactive hypoglycemia are associated with excess insulin (or insufficient glucagon), and avoidance of low blood glucose concentration may help to avoid cramps.
Nocturnal leg crampsNocturnal leg cramps are involuntary muscle contractions that occur in the calves, soles of the feet, or other muscles in the body during the night or (less commonly) while resting. The duration of nocturnal leg cramps is variable with cramps lasting anywhere from a few seconds to several minutes. Muscle soreness may remain after the cramp itself ends. These cramps are more common in older people. They happen quite frequently in teenagers and in some people while exercising at night. The precise cause of these cramps is unclear. Potential contributing factors include dehydration, low levels of certain minerals (magnesium, potassium, calcium, and sodium), and reduced blood flow through muscles attendant in prolonged sitting or lying down. Nocturnal leg cramps (almost exclusively calf cramps) are considered 'normal' during the late stages of pregnancy. They can, however, vary in intensity from mild to extremely painful.
Various medications may cause nocturnal leg cramps: Diuretics, especially potassium sparing Long acting adrenergic beta-agonists (LABAs)
Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) Besides being painful, a nocturnal leg cramp can cause much distress and anxiety. Usually, putting some pressure on the affected leg by walking some distance will end the cramp.
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