Facts on muscle cramps
- Anyone who has experienced a muscle cramp (charley horse) can attest to the fact that it can be quite painful. Muscle cramps or spasms occur when muscles involuntarily contract and cannot relax.
- The term charley horse has been used to refer to painful muscle cramps, particularly when they occur in the leg.
- 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.
What causes a muscle cramp?
It is not known exactly what causes muscle cramps to 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.
Cramps can occur when you are resting, sleeping, or participating in sports or other daily activities. Anyone can develop a muscle cramp but infants, the elderly, the overweight, and athletes are at greatest risk for muscle cramps. Athletes most often develop muscle cramps at the beginning of a season when their body is not yet fully conditioned. Cramps in athletes can occur during or after periods of physical exertion.
How do I stop or prevent muscle cramps?
If you get a muscle cramp while exercising, one strategy is to stop your activity and hold the cramped muscle in a gently stretched position until the cramp resolves. If a cramp occurs when you are lying down, you may want to do just the opposite -- put weight and walk on the cramping leg. Light massage may (or may not) help alleviate the pain.
In athletics, you can also help prevent future muscle cramps by always warming up and stretching well (especially the muscle groups prone to cramping) before workouts and maintaining adequate hydration when exercising. Sports beverages rather than water may help prevent electrolyte imbalances such as low sodium levels (hyponatremia).
Check with your doctor if you have frequent or unusually severe muscle cramps that do not appear to be associated with exercise or do not improve with stretching and massage. Muscle cramps in the legs that come on with exercise can be a sign of a more serious condition called intermittent claudication due to poor circulation of blood to the legs.
Medically reviewed by John A. Daller, MD
American Board of Surgery with subspecialty certification in surgical critical care
Longo, D.L., et al. Harrison's Principles of Internal Medicine, 18th ed. New York: McGraw-Hill Professional, 2011.
Quick GuidePictures of the 7 Riskiest Workout Moves, and How to Improve Them
Daily Health News
Pain and Injury Resources
Subscribe to MedicineNet's General Health Newsletter