painful contraction or tightening of a muscle

Painful contraction or tightening of a muscle/A muscle cramp is a strong, painful contraction or tightening of a muscle that comes on suddenly and lasts from a few seconds to several minutes. It often occurs in the legs. A muscle cramp is also called a charley horse.
Nighttime leg cramps are usually sudden spasms, or tightening, of muscles in the calf. The muscle cramps can sometimes happen in the thigh or the foot. They often occur just as you are falling asleep or waking up.


Groups at increased risk:

• Up to 60% of adults report that they have had nocturnal leg cramps.
• The problem is often distressing, impacting on sleep, and has an adverse effect on the quality of life.
• Pregnant women – up to 30% of women can be affected by leg cramps during pregnancy.
• Muscle cramps are common in children, especially at night.
• Those with metabolic disorders; for example, 50% of patients with uraemia and 20-50% of those with hypothyroidism complain of muscle cramps.
• Athletes and individuals working under hot conditions – eg, firemen.
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Find out what the patient means by cramps:

• Where do they occur?
• When do they occur?
• How often do they occur?
• How long do they last?
• Is there any other relevant medical history such as thyroid disease or cardiovascular disease?
• Are drugs taken? For example, diuretics, salbutamol, nifedipine.
• Ask about alcohol consumption.
• Ask about sport.

Most often, cramps involve the calf or thigh muscles and small muscles of the foot. Of these, the most commonly affected is the calf and it tends to be unilateral.
Cramps occur at rest and usually at night. The most likely explanation is that leg cramps occur when a muscle that is already in a shortened position is involuntarily stimulated. This commonly happens at night where the plantar flexed foot places the calf and ventral foot muscles in the most shortened and vulnerable position. The cramp may last seconds or minutes but post-cramp tenderness may last up to 24 hours.

Risk factors

The exact cause of muscle cramp is not known, but risk factors may include:
• Tight, inflexible muscles
• Poor physical condition
• Poor muscle tone
• Inadequate diet
• Physical overexertion
• Physical exertion of cold muscles
• Muscle injury
• Muscle fatigue
• Excessive perspiration
• Dehydration – caused by, for example, a bout of gastroenteritis
• Reduced blood supply (ischaemia)
• Wearing high-heeled shoes for lengthy periods.

Paraphysiological cramps

• Paraphysiological cramps occur in healthy people in response to a physiological stimulus. They are very common and may occur during sport or in unaccustomed exercise. They are especially likely to occur during endurance sports.
• They are thought to result from hydro-electrolyte imbalance following repeated and chronic use of the same muscle group, producing increased excitation of the neuromuscular nerve endings.[4]
• It is thought that low levels of magnesium and other electrolytes may also play a part.
• They are also very common in pregnancy. The aetiology in pregnancy is unknown: pressure on nerves and blood vessels, circulatory changes and low levels of calcium and magnesium have all been suggested.
• They may also occur in healthy individuals as a result of a sustained posture over a prolonged period of time.

What causes muscle cramps?

Unknown cause (idiopathic leg cramps)

In most cases the cause is not known. One theory is that cramps occur when a muscle that is already in a shortened position is stimulated to contract. As the muscle is already shortened, to contract further may cause the muscle to go into spasm. This commonly happens at night in bed, as the natural position we lie in is with the knees slightly bent (flexed), and with feet pointing slightly downwards. In this position the calf muscle is relatively shortened and may be prone to cramps. This theory explains why stretching exercises may cure the problem.

Secondary causes

In some cases, the cramps may be a symptom of another problem. For example:

• Some medicines can cause cramps as a side-effect, or make cramps occur more often. These include: thiazide diuretics and loop diuretics (water tablets), nifedipine,cimetidine, salbutamol, statins, terbutaline, lithium, penicillamine and phenothiazines (prochlorperazine, perphenazine, chlorpromazine).
• Over-exertion of muscles.
• Dehydration.
• Conditions that cause alterations in the balance of salts in the bloodstream (such as a high or low sodium or potassium level).
• Some people who have kidney (renal) dialysis get leg cramps.
• Pregnancy – usually in the later stages.
• An untreated underactive thyroid gland.
• Peripheral arterial disease (narrowing of the leg arteries which causes poor circulation).
• Excess alcohol.
• Some uncommon disorders of nerves.
• Rare causes include: cirrhosis of the liver; lead poisoning; sarcoidosis.
With the above conditions the cramps would just be one of various other symptoms. Therefore, if you are otherwise well, and have no other unexplained symptoms, then the leg cramps are likely to be of unknown cause (idiopathic) and not due to a secondary cause.

Symptomatic cramps

Cramps may also occur in association with metabolic disturbance, including:

• Hyponatraemia
• Hypokalaemia and hyperkalaemia
• Hypocalcaemia
• Hypomagnesaemia
• Hypoglycaemia
One or more of these may be the underlying aetiology in many of the causes listed below. Blood tests measure the extracellular environment but do not reflect the intracellular fluid which is probably more important.

• Arterial insufficiency.
• Acute or chronic diarrhoea.
• Excessive heat and sweating causing Na+ depletion.
• Hypothyroidism (associated with weakness, enlarged muscles and painful muscle spasms).
• Hyperthyroidism (associated with myopathy).
• Lead poisoning.
• Sarcoidosis.
• Hyperparathyroidism (hypercalcaemia).
• Heavy alcohol ingestion and cirrhosis.
• Hyperventilation-induced respiratory alkalosis.
• Haemodialysis.
• Parenteral nutrition.
• Lower motor neurone disorders including amyotrophic lateral sclerosis, polyneuropathies, recovered poliomyelitis, peripheral nerve injury and nerve root compression.

Drugs causing cramps

Always exclude a medicine-related cause. Implicated drugs include:

• Salbutamol and terbutaline
• Raloxifene
• Opiate withdrawal
• Diuretics cause electrolyte loss
• Nifedipine
• Phenothiazines
• Penicillamine
• Nicotinic acid
• Statins

Idiopathic cramps

This is a diagnosis of exclusion but represents the majority of sufferers. Familial forms exist which appear to have an autosomal dominant mode of transmission.[5] This group also contains conditions such as idiopathic nocturnal cramps and fasciculation-cramp syndrome.

How can you stop a muscle cramp when it happens?

You may need to try several different ways to stop a muscle cramp before you find what works best for you. Here are some things you can try:
• Stretch and massage the muscle.
• Take a warm shower or bath to relax the muscle. A heating pad placed on the muscle can also help.
• Try using an ice or cold pack. Always keep a cloth between your skin and the ice pack.
• Take an over-the-counter pain medicine, such as acetaminophen (Tylenol),ibuprofen (Advil, Motrin), or naproxen (Aleve). Read and follow all instructions on the label.
• If your doctor prescribes medicines for muscle cramps, take them exactly as prescribed. Call your doctor if you have any problems with your medicine.
• Drink plenty of fluids. Sports drinks, such as Gatorade, will often help leg cramps.

Here are some things you can try for a leg cramp

• Walk around, or jiggle your leg.
• Stretch your calf muscles. You can do this stretch while you sit or stand:
o While sitting, straighten your leg and flex your foot up toward your knee. It may help to place a rolled towel under the ball of your foot and, while holding the towel at both ends, gently pull the towel toward you while keeping your knee straight.
o While standing about 2 ft (0.6 m) from a wall, lean forward against the wall. Keep the knee of the affected leg straight and the heel on the ground. Do this while you bend the knee of the other leg. See a picture of how to do this calf stretch .
If you think a medicine is causing muscle cramps:
• Before you take another dose, call the doctor who prescribed the medicine. The medicine may need to be stopped or changed, or the dose may need to be adjusted.
• If you are taking any medicine not prescribed by a doctor, stop taking it. Talk to your doctor if you think you need to continue taking the medicine.


The newest and most scientifically supported theory is that muscle cramps are caused by premature fatigue.2
As you get tired, your muscle’s reflex control becomes dysfunctional. Instead of contracting and relaxing like they’re supposed to, they keep firing. Basically, your muscles become “twitchy” and can’t stop contracting.
This theory is supported by several lines of evidence.

1. The muscles you use the most during your workouts are the ones that usually cramp.
2. Muscles that cross multiple joints are more likely to cramp than other muscles. These muscles generally have more activity during exercise when they’re more likely to get tired.
3. You’re far more likely to cramp during a race than you are in training — when you’re pushing yourself harder than normal. Cramps also tend to occur at the end of races when you’re most fatigued.
4. If you don’t pace yourself properly, you’re more likely to cramp. Athletes who go out too hard relative to their training experience are much more likely to cramp than those who stay within their limits.7,14
5. Drinking pickle juice helps cramps disappear faster than drinking water or nothing at all, and this happens before the salt from the pickle juice can be absorbed. Researchers think this is because the salty taste of the pickle juice “tricks” the brain into relaxing the muscles.12
6. Some evidence indicates that athletes who cramp have more muscle damage before races.14
At this point, there’s no direct evidence that consuming extra electrolytes will help you avoid muscle cramps. There’s some evidence that dehydration might be involved, but it’s almost certainly not the primary cause of your muscle cramps.

Differential diagnosis:


• Restless legs (Ekbom’s syndrome).
• Intermittent claudication and ischaemic rest pain.
• Muscle injury or strain.
• Hypnagogic muscle jerking (when falling asleep).
• Lumbar nerve root entrapment.
• Ruptured Baker’s cyst.
• Deep vein thrombosis or thrombophlebitis.
• Peripheral neuropathy.
• Occupational cramps – eg, writer’s cramp or musician’s cramp (focal dystonias, usually affecting the upper limb).
• Causes of generalised muscle pain – eg, polymyositis, toxoplasmosis, alcohol-related myopathy, Guillain-Barré syndrome, polymyalgia rheumatica, Parkinsonism,fibromyalgia.


• During an attack the affected muscle or group is hard and tender.
• Between attacks examination is unlikely to be rewarding.
• The muscle may be tender for up to 24 hours after the previous attack.
• In the elderly or where peripheral arterial disease is suspected, check for peripheral pulses and capillary refill.
• Look for signs of neurological disease – eg, muscle wasting and fasciculations, altered reflexes, sensory or power loss.

Usually no investigation is indicated. They may be performed if an underlying cause is suspected.

Potential investigations include:
• U&Es
• LFTs
• TFTs
• Serum calcium or magnesium
• Creatine kinase
• Lead levels


Decision Aids
Doctors and patients can use Decision Aids together to help choose the best course of action to take.

• In most cases the aetiology is benign and the patient needs to be reassured of this whilst steps are taken to help alleviate the problem. Exclude known causes of muscle cramps without excessive and unnecessary investigation.
• Management depends upon the cause of the problem. Review drugs. Address any correctable problems – eg, use of diuretics and electrolyte imbalance.
• The severity of symptoms and their impact on sleep, mood, and quality of life will determine whether treatment is required. Asking patients to keep a sleep and cramp diary may be helpful to assess progress.[6]
• The evidence base for management of this common but usually benign condition is not strong.


• Passive stretching and massage of the affected muscle will help ease the pain of an acute attack – eg, for calf cramping, straighten the leg with dorsiflexion of the ankle or heel walk until the acute pain resolves.
• Regular stretching of the calf muscles throughout the day may help to prevent acute attacks. Some people recommend stretching three times daily whilst others advocate stretching before going to bed.
• Using a pillow to raise the feet through the night, or raising the foot of the bed may help to prevent attacks in some people.

Note that whilst stretching exercises are unlikely to do harm, evidence for their efficacy is contradictory. In sport, stretching is widely advocated as likely to reduce injury and cramp but the quality of evidence tends to be poor, with failure to distinguish benefit from that due to improvement in physical fitness from training.[7] Avoiding over-training and risky conditions (eg, hot and humid environmental conditions) can be useful in preventing cramps.[8]
The value of massage, over and above psychological benefit, is also questioned


• Quinine sulfate has been the most frequently used drug in the UK for the treatment of leg cramps in non-pregnant individuals who have not responded to conservative measures.
• However, it is not generally recommended due to the poor benefit-to-risk ratio. The Food and Drug Administration (FDA) in America has banned the use of quinine for this indication.
• Quinine has an extensive side-effect profile, including thrombocytopenia as an important but rare complication. Evidence for its long-term efficacy is lacking.
• However, a Cochrane review found that there was moderate evidence that quinine significantly reduces cramp frequency, intensity and cramp days in dosages between 200 and 500 mg/day. There was moderate evidence that with use up to 60 days, the incidence of serious adverse events was not significantly greater than for placebo in the identified trials.[10]
• A therapeutic trial approach may be used where self-care measures fail and leg cramps are frequent and affecting the person’s quality of life:[3][11]
• Prescribe 200-300 mg nocte for 4-6 weeks.
• Monitor using a sleep and cramp diary.
• If helpful, continue treatment for three months, then stop to reassess ongoing need.
• If ongoing treatment is required, regular medication reviews should occur every 3-6 months.
• Quinine can frequently be stopped without a recurrence of troublesome symptoms.[12]
• Potential drug alternatives to quinine include verapamil and gabapentin in the general population and vitamin E or L-carnitine in the dialysis population.[13][14]
• Avoid quinine in pregnancy and concentrate on nondrug measures where possible. Calcium lactate is ineffective but magnesium supplements may help relieve the symptoms in pregnant women who have not responded to conservative measures.[15]
• Traditionally, sodium chloride has been thought to be beneficial, although the trial evidence is old and the potential of added salt to cause hypertension may cause

Preventing Muscle Cramps

Until we learn the exact cause of muscle cramps, it will be difficult to say with any confidence how to prevent them. However, these tips are most recommended by experts and athletes alike:

• Improve fitness and avoid muscle fatigue
• Stretch regularly after exercise
• Warm up before exercise
• Stretch the calf muscle: In a standing lunge with both feet pointed forward, straighten the rear leg.
• Stretch the hamstring muscle: Sit with one leg folded in and the other straight out, foot upright and toes and ankle relaxed. Lean forward slightly, touch foot of straightened leg. (Repeat with the opposite leg.)
• Stretch the quadriceps muscle: While standing, hold the top of foot with the opposite hand and gently pull heel toward buttocks. (Repeat with the opposite leg.)
Most muscle cramps are not serious. If your muscle cramps are severe, frequent, constant or of concern, see your doctor.

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