What Is a Charley Horse and How Did It Get Its Name?
Charley horse is a term that describes a strain or soreness of a muscle. A Charley horse occurs when your muscles work too hard at exercises they are not used to.
The expression originated in England, where “Charley” was once a common name for horses that had grown too old for work and were kept for family use. The name became popular in the United States as slang for lame racehorses, and for the muscle strains that temporarily disable athletes.
A charley horse will usually go away after a few hours but it sometimes takes several days for the soreness of a Charley horse to go away. Relief is usually given by either massaging or stretching the foot, ankle or knee in the opposite direction of the spasm.
Colloquial advice suggests that dietary deficiency of potassium, found richly in bananas and many vegetables, is a common cause of these spasms.