Muscle cramps are painful, sustained contractions of all of the fibers in a muscle. They can last for just a few seconds or continue for several hours.

Any Muscle can cramp. The cramp can be so mild that you will feel only a slight muscle twitch or so severe that it can break a bone. Although cramps can occur during sleep, they usually occur during intense exercise. No athlete or fitness buff in any sport is immune to this common condition.

• Salt deficiency
• Low levels of other minerals such as potassium or Magnesium
• An injury or strain on the muscle
• An obstruction of the muscle's blood supply by sustained muscular contractions
• Hyperventilating -- breathing too fast when it is not necessary, which prevents the body from using calcium