What causes Charlie Horses?

“A charley horse is a popular North American colloquial term for a painful contusion (bruise) of the quadriceps muscle of the anterior or lateral thigh that commonly results in a muscular hematoma and sometimes several weeks of pain and disability. Such an injury is known in the UK and many Commonwealth countries (and also in the U.S.) as a dead leg. In Australia it is also known as a corked thigh or “corkie”. It often occurs in sports when an athlete is struck by an opponent’s knee, in a manner like the kick of a horse, perhaps the reason for its name….It could also be as simple as not enough magnesium or potassium, or too much calcium.”

~Wikipedia

Simple answer: It’s a bruise, or a cramp. :)

The charley horse that wakes you up from a sound sleep, screaming, quite often be a potassium deficiency. These are usually in the calf or foot and can temporarily stopped be bending the musle against the cramp. To reduce the number of cramps you might try eating 3–4 bananas a week.

For older people muscles may cramp because of lack of use. Besides the foot and calf muscless, you can get them in a chain reaction from the ankle through all the muscles right up to your groin on the inside of your leg-now that really smarts!

True Humor: Just before I saw this question (it is the sibling to the question I was at) I got a charlie horse in my foot.

drink more water.