A swimmer can be swimming along quite happily when suddenly he feels a sharp painful contraction of a muscle. A person can be sleeping peacefully, to be suddenly awoken by a painful contraction in the calf or in the soles of the feet. These fierce contractions are called ‘cramp’. In cramp, all the muscular fibres receive a strong nervous impulse which contracts them, but does not let them relax.
Intense muscular activity can cause cramp. But quite often, as in the case of the sleeper, it results from a lack of certain minerals in the body. An analysis of the minerals in our blood can reveal the causes of cramp. It shows that the individual who has frequent cramp, which is not due to intense muscle fatigue caused by physical exercise, has a shortage of calcium, phosphorus or magnesium. His supply has either provided him with insufficient minerals, or else he has difficulty in assimilating minerals (absorbing them into the bloodstream).
This difficulty in assimilation may be caused by a lack of certain vitamins: vitamin D for phosphorus and calcium, for example.
Nervous problems can also cause cramp: anxiety or fatigue of the nervous system, for example. Sometimes poor liver function is responsible.
The causes of cramp are sometimes difficult to discover, especially when they appear periodically. This is the case with women, during the second phase of their menstrual cycle: that is to say, when they are under the influence of certain hormones (internal secretions).