Charley Horse

A "Charley horse" or "Horse Gummit" is a popular North American colloquial term for painful spasms or cramps in the leg muscles, typically lasting anywhere from a few seconds to a few hours. It can also refer to a bruise on an arm or leg and a bruising of the quadriceps muscle of the anterior or lateral thigh, or contusion of the femur, that commonly results in a hematoma and sometimes several weeks of pain and disability. Such an injury is known in the United Kingdom, United States, and many Commonwealth countries as a dead leg, granddaddy, or chopper. In Australia it is also known as a corked thigh or "corky." It often occurs in sports, such as football when an athlete suffers a knee (blunt trauma) to the lateral quadriceps causing a hematoma or temporary paresis and antalgic gait as a result of pain.

Another nuance for the term "charley horse" is used to describe simple painful muscle cramps in the leg or foot, especially those that follow strenuous exercise. These muscle cramps can have many possible causes directly resulting from high or low pH or substrate concentrations in the blood, including hormonal imbalances, low levels of potassium or calcium, side effects of medication, or, more seriously, diseases such as amyotrophic lateral sclerosis and neuropathy. They are also a common complaint during pregnancy.