Muscle cramp
A muscle cramp is an uncontrollable and painful spasm of a muscle. Any muscle can be affected, but the muscles of the calf and foot are particularly prone. A cramp can last for varying periods of time and generally resolves by itself. The exact cause of cramp is unknown but risk factors may include poor physical condition, mineral and electrolyte imbalances and tight, inflexible muscles. Cramps are usually harmless but may sometimes be symptomatic of an underlying medical disorder, such as atherosclerosis (narrowing of the arteries), so regular cramping or severe cramping that lasts longer than a few minutes should always be investigated by your doctor.