Answer:
A muscle that involuntarily contracts is called a 'Spasm'. If the spasm is forceful and sustained, it becomes a cramp. A muscle cramp is thus an involuntarily and forcibly contracted muscle that does not relax. It causes unpleasant and often painful sensations in the affected area.
A muscle cramp can be caused by various reasons:
- Dehydration - Sports and other activities can cause excessive fluid loss from perspiration. These cramps are more likely in warm weather and can be an early sign of heat stroke. Chronic volume depletion of body fluids from diuretics (medicine that promote urination) and poor fluid intake may act similarly to predispose to cramps in seniors. Sodium depletion has also been associated with cramps. Loss of sodium, the most abundant chemical constituent of body fluids outside the cell, is usually a function of dehydration.
- Injury - Persistent muscle spasm may occur as a protective mechanism following an injury, such as a broken bone.
- Vigorous activity - Vigorous use of muscles and muscle fatigue in sports or with unaccustomed activities causes cramps during the activity or later, sometimes many hours later. Elderly are at more risk for cramps when performing vigorous or strenuous physical activities.
- Muscle fatigue - Muscle fatigue from sitting or lying for an extended period in an awkward position or any repetitive use can cause cramps.
- Body fluid changes - Cirrhosis of the liver, with fluid in the abdominal cavity (ascites) and hemodialysis involve rapid body fluid changes which frequently complicates into cramps.
- Low blood calcium, magnesium - Low blood levels of either calcium or magnesium directly increase the excitability of both the nerve endings and the muscles they stimulate.
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