Definition of Charley horse
A charley horse is the common name for a muscle spasm, especially in the leg. Muscle spasms can occur in any muscle in the body. When a muscle is in spasm, it contracts without your control and does not relax.
Causes, incidence, and risk factors
Muscle spasms often occur when a muscle is overused or injured. Working out when you haven’t had enough fluids (you’re dehydrated) or when you have low levels of minerals such as potassium or calcium can also make you more likely to have muscle spasms.
When a muscle goes into spasm it feels very tight and is sometimes described as a knot. The pain can be severe.
Signs and tests
Your health care provider can diagnose muscle spasms by the presence of tight or hard muscles that are very tender to the touch. There are no imaging studies or blood tests that can diagnose this condition. If the spasm is caused by nerve irritation, such as in the back, an MRI may be helpful to find the cause of the irritation.
At the first sign of a muscle spasm, stop your activity and try stretching and massaging the affected muscle. Heat will relax the muscle at first, although ice may be helpful after the first spasm and when the pain has improved. If the muscle is still sore, nonsteroidal anti-inflammatory medications can help with pain. In more severe cases, your health care provider can prescribe antispasm medications.
Muscle spasms will get better with rest and time. The outlook is excellent for most people. Proper training techniques should prevent spasms from occurring regularly. If an irritated nerve caused the spasm, you might need more treatment and results can vary.
Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and C. Benjamin Ma, MD, Assistant Professor, Chief, Sports Medicine and Shoulder Service, UCSF Dept of Orthopaedic Surgery. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. – 7/10/2009