Cramp also called a Spasm, is an involuntary muscle contraction, which lasts only a short time, (less than 15 minutes and often only a matter of seconds). Leg cramps often happen during rest and especially at night.
Cramp often is worse during pregnancy, after physical exercise and very common in older adults. Cramps are called idiopathic because there's no underlying pathology, however we know that they are sudden muscle pains and can cause a paralysis like immobility which is luckily short lived. Cramp is associated with dehydration and not having enough electrolytes, it also can be exacerbated by not stretching before and after exercise.
Causes
Inadequate blood supply during exercise leads to the narrowing of your arteries that deliver the blood to your legs, which causes the cramp like pain in your feet and legs which normally diminishes as soon as you cease exercising.
Mineral depletion causing a deficiency of potassium, calcium or magnesium in your diet can contribute to leg cramps. Diuretics for example & medications that are prescribed for high blood pressure could also deplete these minerals.
Cramp seems to be more prevalent in older people or in athletes who become fatigued and dehydrated, or people with certain medical conditions, such as diabetes or nerve, liver or thyroid disorders.
Prevention
Avoid dehydration; drink plenty of liquids every day and remember to consider your level of activity, the weather, your health, your age and the medications you take.
Fluids help your muscles contract and relax and keep cells hydrated during activity, replenish fluids at regular intervals and continue drinking water or other fluids after you finished exertion.
If you tend to have leg cramps at night, stretch before bedtime, light exercise may help to prevent cramp - I have included some suggestions in the download below.
If your cramps are becoming more frequent or they are accompanied by associated muscle loss you should consult a doctor.
Stretching has benefits for everyone regardless of their level of activity. Since the legs are most prone to cramping, concentrate on warming up those major muscle groups first.
Massage the area that cramps, you will find the area affected can be eased with heat, for example a microwavable rice bag can be placed on the affected area and ease tense muscles.
Stay hydrated.
Consider your diet, cramp is caused or linked to the levels of calcium, potassium and magnesium; so look at your diet and try to include foods rich in those minerals.