Muscle Cramp / Calf Cramp

It comes suddenly. Often at night, when you have just fallen asleep or are turning over in bed. Sometimes in the middle of a movement, during sport, on the stairs. A muscle — usually the calf, sometimes the foot, sometimes the thigh — contracts and will not let go again. It is not a slow pain, but a grip. Your leg becomes hard as wood, the muscle stands beneath you like a cable under tension, and you can do nothing but wait until it releases you.