In general, a muscle cramp is an involuntary contraction of a muscle that doesn’t relax. The most common places for this to occur is in the legs and feet. They can last anywhere from a few seconds to a few minutes and can sometimes occur several times until the initial ‘trigger’ is resolved. They are extremely common, and it is estimated that almost everyone will experience one at sometime in their life with the chance of occurrence increasing with age.
Any muscle under voluntary control can have a cramp (skeletal muscles), but involuntary muscles can also cramp, but uncommon, are the bowels, urinary path and uterus.
There are various different types of cramps for skeletal muscles; true, tetany, contractures and dystonic cramps, each with it’s own specific causes or muscles. True cramps involve part or all of a single muscle or a group of muscles that generally act together, such as the muscles that flex several adjacent fingers or the leg muscles. Most authorities agree that true cramps are caused by hyperexcitability of the nerves that stimulate the muscles. They are overwhelmingly the most common type of skeletal muscle cramps. True cramps can occur in a variety of circumstances as follows.
A prior injury can also be a cause for a cramp or consistent muscle spasms, acting as a protective measure to minimise movement and speed up recovery.