Medical Author: Melissa Stöppler, MD
Medical Editor: William C. Shiel, Jr., FACP, FACR
Anyone who has experienced a muscle cramp (charley horse) can attest to the fact that it can be quite painful. Muscle cramps occur when muscles involuntarily contract and cannot relax.
The skeletal muscles (those over which we have voluntary control) are most prone to cramping. The skeletal muscles in the calf, thigh, and arch of the foot are most notorious sites of cramps.
Cramps can be perceived as mild twitches or may be excruciatingly painful. Typically, cramps cause an abrupt, intense pain in the involved muscle.
Often a muscle that is cramping feels harder than normal to the touch or may even show visible signs of twitching. Most cramps resolve spontaneously within a few seconds to minutes.
It is not known exactly why muscle cramps develop. Insufficient stretching before exercise, exercising in the heat, and muscle fatigue may all play a role in their causation. Imbalances in the levels of electrolytes (sodium, potassium, chloride, calcium and phosphate) in the blood can also lead to muscle cramps.