Muscle Cramp Treatment, Definition, Medication, Causes, Prevention

A runner experiences a muscle cramp in his calf.Source: iStock

Facts you should know about muscle cramps

A muscle cramp is an involuntarily and forcibly contracted muscle that does not relax.
Muscle cramps can occur in any muscle; cramps of the leg muscles and feet are particularly common.
Almost everyone experiences a muscle cramp at some time in their life.
There are a variety of types and causes of muscle cramps.
Muscle cramps may occur during exercise, at rest, or at night, depending upon the exact cause.
Dehydration is a common cause of muscle cramps.
Numerous medicines can cause muscle cramps.
Most muscle cramps can be stopped if the muscle can be stretched.
Muscle cramps can often be prevented by measures such as adequate nutrition and hydration, attention to safety when exercising, and attention to ergonomic factors.

Muscle Cramps: A Real Pain

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.

Read about treatment of muscle cramps »

Anatomy illustration of the muscle.Source: MedicineNet

What are muscle cramps?

A muscle cramp is an involuntarily and forcibly contracted muscle that does not relax. When we use the muscles that can be controlled voluntarily, such as those of our arms and legs, they alternately contract and relax as we move our limbs. Muscles that support our head, neck, and trunk contract similarly in a synchronized fashion to maintain our posture. A muscle (or even a few fibers of a muscle) that involuntarily (without consciously willing it) contracts is in a "spasm." If the spasm is forceful and sustained, it becomes a cramp. Muscle cramps often cause a visible or palpable hardening of the involved muscle.

Muscle cramps can last anywhere from a few seconds to a quarter of an hour or occasionally longer. It is not uncommon for a cramp to recur multiple times until it finally resolves. The cramp may involve a part of a muscle, the entire muscle, or several muscles that usually act together, such as those that flex adjacent fingers. Some cramps involve the simultaneous contraction of muscles that ordinarily move body parts in opposite directions.

Muscle cramps are extremely common. Almost everyone (one estimate is about 95%) experiences a cramp at some time in their life. Muscle cramps are common in adults and become increasingly frequent with aging. However, children also experience cramps of muscles.

Any of the muscles that are under our voluntary control (skeletal muscles) can cramp. Cramps of the extremities, especially the legs and feet (including nocturnal leg cramps), and most particularly the calf (the classic "charley horse"), are very common. Involuntary muscles of the various organs (uterus, blood vessel wall, bowels, bile and urine passages, bronchial tree, etc.) are also subject to cramps. Cramps of the involuntary muscles will not be further considered in this review. This article focuses on cramps of skeletal muscle.

Human anatomy of the muscles.Source: iStock

What are the types and causes of muscle cramps?

Skeletal muscle cramps can be categorized into four major types. These include "true" cramps, tetany, contractures, and dystonic cramps. Cramps are categorized according to their different causes and the muscle groups they affect.

Types of muscle cramps: True cramps

True cramps involve part or all of a single muscle or a group of muscles that generally act together, such as the muscles that flex several adjacent fingers or the leg muscles. Most authorities agree that true cramps are caused by hyperexcitability of the nerves that stimulate the muscles. They are overwhelmingly the most common type of skeletal muscle cramps. True cramps can occur in a variety of circumstances as follows.

A female runner experiences a leg cramp on the track.Source: iStock

Injury and vigorous activity muscle cramps

Injury: Persistent muscle spasm may occur as a protective mechanism following an injury, such as a broken bone. In this instance, the spasm tends to minimize movement and stabilize the area of injury. Injury of the muscle alone may cause the muscle to spasm.

Vigorous activity: True cramps are commonly associated with the vigorous use of muscles and muscle fatigue (in sports or with unaccustomed activities). Such cramps may come during the activity or later, sometimes many hours later. Likewise, muscle fatigue from sitting or lying for an extended period in an awkward position or any repetitive use can cause cramps. Older adults are at risk for cramps when performing vigorous or strenuous physical activities.

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A person sits up in bed with a foot cramp.Source: iStock

Rest cramps and dehydration muscle cramps

Rest cramps: Cramps at rest are very common, especially in older adults, but may be experienced at any age, including childhood. Rest muscle cramps often occur at night. While not life threatening, night cramps (commonly known as nocturnal cramps) can be painful, disruptive of sleep, and they can recur frequently (that is, many times a night, and/or many nights each week). The actual cause of night cramps is unknown. Sometimes, such cramps are initiated by making a movement that shortens the muscle. An example is pointing the toe down while lying in bed, which shortens the calf muscle of the leg, a common site of muscle cramps.

Dehydration: Sports and other vigorous activities, including activities of endurance athletes, can cause excessive fluid loss from perspiration. This kind of dehydration increases the likelihood of true cramps. These cramps are more likely to occur in warm weather and can be an early sign of heat stroke. Chronic volume depletion of body fluids from diuretics (medicine that promote urination) and poor fluid intake both lead to dehydration and may act similarly to predispose to cramps, especially in older people. Sodium depletion has also been associated with cramps. Loss of sodium, the most abundant chemical constituent of body fluids outside the cell, is usually a function of dehydration.

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A chart shows calcium (Ca), magnesium (Mg), and potassium (K) elements.Source: iStock

Body fluid shifts, low blood calcium, and low potassium muscle cramps

Body fluid shifts: True cramps also may be experienced in other conditions that feature an unusual distribution of body fluids. An example is cirrhosis of the liver, which leads to the accumulation of fluid in the abdominal cavity (ascites). Similarly, cramps are a relatively frequent complication of the rapid body fluid changes that occur during dialysis for kidney failure.

Low blood calcium or magnesium: Low blood levels of either calcium or magnesium directly increase the excitability of both the nerve endings and the muscles they stimulate. This may be a predisposing factor for the spontaneous true cramps experienced by many older adults, as well as for those muscle cramps that are commonly noted during pregnancy. Low levels of calcium and magnesium are common in pregnant women unless these minerals are supplemented in the diet. Cramps are seen in any circumstance that decreases the availability of calcium or magnesium in body fluids, such as taking diuretics, hyperventilation (overbreathing), excessive vomiting, inadequate calcium and/or magnesium in the diet, inadequate calcium absorption due to vitamin D deficiency, poor function of the parathyroid glands (tiny glands in the neck that regulate calcium balance), and other conditions.

Low potassium: Low potassium blood levels occasionally cause muscle cramps, although it is more common for low potassium to be associated with muscle weakness.

Nerve cells activated in the body.Source: Bigstock

Types of muscle cramps: Tetany

In tetany, all of the nerve cells in the body are activated, which then stimulate the muscles. This reaction causes spasms or cramps throughout the body. The name tetany is derived from the effect of the tetanus toxin on the nerves. However, the name is now commonly applied to muscle cramping from other conditions, such as low blood levels of calcium and magnesium. Low calcium and low magnesium, which increase the activity of nerve tissue nonspecifically, also can produce tetanic cramps. Often, such cramps are accompanied by evidence of hyperactivity of other nerve functions in addition to muscle stimulation. For instance, low blood calcium not only causes spasm of the muscles of the hands and wrists, but it can also cause a sensation of numbness and tingling around the mouth and other areas.

Sometimes, tetanic cramps are indistinguishable from true cramps. The accompanying changes of sensation or other nerve functions that occurs with tetany may not be apparent because the cramp pain is masking or distracting from it.

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A girl plays the violin.Source: Medscape

Types of muscle cramps: Dystonic cramps

The final category is dystonic cramps, in which muscles that are not needed for the intended movement are stimulated to contract. Muscles that are affected by this type of cramping include those that ordinarily work in the opposite direction of the intended movement, and/or others that exaggerate the movement. Some dystonic cramps usually affect small groups of muscles (eyelids, jaws, neck, larynx, etc.). The hands and arms may be affected during the performance of repetitive activities such as those associated with handwriting (writer's cramp), typing, playing certain musical instruments, and many others. Each of these repetitive activities may also produce true cramps from muscle fatigue. Dystonic cramps are not as common as true cramps.

Arrow shows a fifth digit joint contracture on the small finger of the right hand.Source: iStock

What can mimic a muscle cramp?

A contracture is a condition that may mimic a muscle cramp.

A contracture is a scarring of the soft tissues that muscle movements normally affect. When a contracture is present, the tissue that is involved cannot move completely, whether the corresponding muscle is activated or relaxed. This is because the scarred tissue cannot move in response to muscle movements. This leads to a fixed body part with loss of full range of motion. The most common type of contracture occurs in the palm of the hand and affects the tendons that normally cause the fingers to close with gripping. Most commonly, this form of contracture affects the ring finger. This contracture is known as a Dupuytren's contracture of the hand.

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A runner takes a bottle of water during a race.Source: Bigstock

How much should I drink to prevent muscle cramps?

How much should I drink? Hydration guidelines should be individualized for each person. The goal is to prevent excessive weight loss (>2% of body weight). You should weigh yourself before and after exercise to see how much fluid you lose through sweat. One liter of water weighs 2.25 pounds. Depending on the amount of exercise, temperature and humidity, body weight, and other factors, you can lose anywhere from approximately .4 to 1.8 liters per hour.

Pre-exercise hydration (if needed):
1. 0.5 liters per hour for a 180-pound person several hours (three to four hours) prior to exercise.
2. Consuming beverages with sodium and/or small amounts of salted snacks or sodium-containing foods at meals will help to stimulate thirst and retain the consumed fluids.
During exercise:
1. Suggested starting points for marathon runners are 0.4 to 0.8 liters per hour, but again, this should be individualized based on body weight loss.
2. There should be no more than 10% carbohydrate in the beverage, and 7% has generally been considered close to optimal. Carbohydrate consumption is generally recommended only after one hour of exertion.
3. Electrolyte repletion (sodium and potassium) can help sustain electrolyte balance during exercise, particularly when
  - there is inadequate access to meals or meals are not eaten,
  - physical activity exceeds four hours in duration, or
  - during the initial days of hot weather.
Under these conditions, adding modest amounts of salt (0.3 g/L to 0.7 g/L) can offset salt loss in sweat and minimize medical events associated with electrolyte imbalances (for example, muscle cramps, hyponatremia).

Post-exercise:
1. Drink approximately 0.5 liters of water for every pound of body weight lost.
2. Consuming beverages and snacks with sodium will help expedite rapid and complete recovery by stimulating thirst and fluid retention.
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A pregnant woman experiences neck cramps and lower back pain.Source: iStock

Is it possible to prevent muscle cramps during pregnancy?

During pregnancy: Supplemental calcium and magnesium have each been shown to help prevent cramps associated with pregnancy. An adequate intake of both of these minerals during pregnancy is important for this and other reasons, but supervision by a qualified health care professional is essential.

While experiencing dystonic cramps: Cramps that are induced by repetitive non-vigorous activities can sometimes be prevented or minimized by careful attention to ergonomic factors such as wrist supports, avoiding high heels, adjusting chair position, activity breaks, and using comfortable positions and equipment while performing the activity. Learning to avoid excessive tension while executing problem activities can help. However, cramps can remain very troublesome for activities that are difficult to modify, such as playing a musical instrument.

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A woman stretches before bed.Source: iStock

Is it possible to prevent rest cramps?

While experiencing rest cramps: Nocturnal cramps and other rest cramps can often be prevented by regular stretching exercises, particularly if done before going to bed. Even the simple calf-stretching maneuver (described in the first paragraph of the section on treatment), if held for 10 to 15 seconds and repeated two or three times just before going to bed, can be a great help in preventing nocturnal leg cramps. The maneuver can be repeated each time you get up to go to the bathroom during the night and also once or twice during the day. If nocturnal leg cramps are severe and recurrent, a foot board can be used to simulate walking even while recumbent and may prevent awkward positioning of the feet during sleep. Ask your doctor about this remedy.

Another important aspect of prevention of night cramps is adequate calcium and magnesium. Blood levels may not be sensitive enough to accurately reflect what is happening at the tissue surfaces where the hyperexcitability of the nerve occurs. Calcium intake of at least 1 gram daily is reasonable, and 1.5 grams may be appropriate, particularly for women with or at risk for osteoporosis. An extra dose of calcium at bedtime may help prevent cramps.

Supplemental magnesium may be very beneficial for some, particularly if the person has a magnesium deficiency. However, added magnesium can be very hazardous for people who have difficulty eliminating magnesium, as happens with kidney insufficiency. The vigorous use of diuretics usually increases magnesium loss, and high levels of calcium intake (and therefore of calcium excretion) tend to increase magnesium excretion. Magnesium is present in many foods (greens, grains, meat and fish, bananas, apricots, nuts, and soybeans) and some laxatives and antacids, but a supplemental dose of 50-100 milligrams of magnesium daily may be appropriate. Splitting the dose and taking a portion several times during the day minimizes the tendency to diarrhea that magnesium can cause.

Vitamin E has also been said to help minimize cramp occurrence. Scientific studies documenting this effect are lacking, but anecdotal reports are common. Since vitamin E is thought to have other beneficial health effects and is not toxic in usual doses, taking 400 units of vitamin E daily is approved, recognizing that documentation on its effect on cramps is lacking.

A woman takes her vitamin.Source: iStock

Are there particular concerns for older adults?

Older adults should have periodic magnesium blood levels taken if they use supplemental magnesium. Even a mild and otherwise not apparent degree of kidney dysfunction, which is often seen in this age group, may lead to toxic levels of magnesium with modest doses.

Recent studies have indicated that vitamin D (a vitamin required for the normal absorption of calcium from food) deficiency is common in some elderly individuals. Consequently, vitamin D replacement is important for these people, taking appropriate care to avoid excessive vitamin D levels, as these are toxic. An intake at least 400 units daily has been recommended in the past; more recently, experts have questioned whether this dose of vitamin D is sufficient, especially for people with little or no sun exposure (sunlight promotes the formation of vitamin D in the body). However, excessive doses of vitamin D are known to be toxic. The upper limit of dosing for vitamin D supplementation has been recommended as 2,000 IU daily. Your health care professional can help you decide how much vitamin D you should take, taking your individual situation and medical history into account.

While the more potent diuretics are associated with an increased loss of calcium and magnesium, hydrochlorothiazide (HydroDIURIL and others) and related diuretics are associated with calcium and magnesium retention. Diuretics are commonly used for the treatment of hypertension and heart failure. If cramps (or osteoporosis) are also a problem, the patient and doctor may consider using hydrochlorothiazide or another thiazide type of diuretic if otherwise feasible and appropriate.

Diuretics also cause sodium depletion and most also cause potassium depletion. Many patients who use diuretics are also on sodium-restricted diets. Careful attention to the effects of diuretics on sodium and potassium, and replacement of these elements as needed, is always appropriate, even more so if cramps are a problem.

Older adults often do not hydrate themselves adequately, partly because the sense of thirst diminishes with age. This situation is exaggerated in those who are treated with diuretics. For some, simply increasing fluid intake to the generally recommended six to eight glasses a day will improve the cramps. However, drinks with caffeine should not be counted since they act on the kidneys to increase fluid loss. Individuals who are on restricted fluid intake should consult their doctor on this issue and must not ignore their recommended fluid intake limits.

As for night cramps, the exact cause is often difficult to determine. The best prevention involves stretching regularly, adequate fluid intake, appropriate calcium and vitamin D intake, supplemental vitamin E, and possibly — with physician consultation — supplemental magnesium intake.

Capsules of medication.Source: iStock

Are there medications to prevent muscle cramps?
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In recent times, the only medication that has been widely used to prevent, and sometimes also to treat, cramps is quinine. Quinine has been used for years in the treatment of malaria. Quinine acts by decreasing the excitability of the muscles. It has also been shown to be effective in many, but not all, scientific studies. However, quinine also causes birth defects and miscarriages as well as serious side effects. It has also occasionally caused hypersensitivity reactions and a deficiency of platelets, which are the blood components responsible for clotting. Either of these reactions can be fatal. Quinine is also associated with a cluster of symptoms called cinchonism (nausea, vomiting, headaches, and deafness). Additionally, vision and heart irregularities can occur. Consequently, quinine tablets are not available in the United States. Quinine is available in grocery stores in tonic water. The U.S. FDA does not recommend or endorse the use of quinine to treat or prevent muscle cramps. Nevertheless, quinine is sometimes recommended as quinine water (tonic water) prior to bedtime to prevent night muscle cramps. Always consult your health care professional before taking quinine for cramps.

A doctor examines a patient’s leg.Source: iStock

What is the prognosis of recurrent muscle cramps?

Although cramps can be a great nuisance, they are a benign condition. Their importance is limited to the discomfort and inconvenience they cause, or to the diseases associated with them. Careful attention to the preceding recommendations will greatly diminish the problem of cramps for most individuals. Those with persistent or severe muscle cramps should seek medical attention.