A charley horse is a North American term for a painful contusion (bruise) of the quadriceps muscle of the anterior thigh that commonly results in a muscular hematoma and sometimes several weeks of pain and disability. It often occurs in sports when an athlete is struck by an opponent's knee, in a manner not unlike the kick of a horse, perhaps the reason for its name. In the UK and Commonwealth countries, such an injury is known as a dead leg, corky, or corkie. citation needed]
The term Charley Horse is commonly used to describe leg/foot cramping. "This out-of-the-blue leg cramp is as intense as a kick from a palomino. "You'll be lying in bed or even asleep when you get this terrible knot-usually in the calf but sometimes in the thigh or the arch of your foot," says Steven Subotnick, D.P.M., a sports podiatrist. This type of out of the blue Charley Horse can often be caused by mineral deficiencies, or an electrolyte imbalance.