HEALTH / Common Complaints: Cramp

CRAMP is very rarely researched. Yet almost everyone has had an attack, and it may be extremely painful and sometimes dangerous. Typical cramp causes an involuntary tightening of the muscles, usually in the calves of the legs and in the feet, sometimes giving a sensation that the muscles and tendons have become knotted and lumpy. While it persists, the muscles are so painful that they are almost useless.

Some of the causes of cramp - or at least the circumstances that bring it on - are known. Sportsmen may develop cramp after unusually prolonged physical effort. Cramp is more likely in someone who has sweated a lot and failed to replace the salt and water. Britons who go south in search of the sun and then climb mountains or play tennis in the heat of the day are at high risk; after a week or so,

the body adjusts better to exercise in hot conditions and the chances of an attack of cramp become lower.

Cramp while swimming may induce panic and so, very occasionally, lead to drowning. Fear of this scenario meant that previous generations of children were forbidden to swim until at least an hour after their midday meal. This prohibition is no longer universal, though it has a sound basis - the blood flow is diverted from the muscles to the stomach and intestines while a meal is being digested. But nowadays children do tend to snack throughout the day rather than have a large midday meal.

Cramp in the young and fit is annoying but is rarely frequent. In the elderly, by contrast, cramp in bed may become a repetitive cause of misery at night. No one knows why these attacks of cramp become more common with age; they occur in people who are otherwise in perfect health. There are many folk remedies, such as raising the foot of the bed (not a good idea if you suffer from heartburn or indigestion), and a range of drug treatments has been tried. The most widely used is quinine; a single dose of one of the standard antimalarial tablets taken at night will often give reliable relief.

Another problem that troubles people in bed at night is restless legs, or Ekbom's syndrome. This is a sensation of discomfort in the calves which can only be relieved by moving them. The feeling comes on just as the sufferer is about to go to sleep, and the condition is thought to be related to the involuntary movements that many people make while sleeping. Further episodes may occur, but they usually become less frequent as the night progresses. As with nocturnal cramp, the cause of the restless legs syndrome is unknown and it does not threaten health. Treatment with calcium channel blockers, a category of drugs that slows muscle activity, is sometimes effective.