What is a Cramp?


A cramp is defined as a spontaneous or involuntary electrical activity of a large number of skeletal muscle fibres that quickly develops into a painful, sustained contraction (muscle spasm).

Cramps can be divided into two categories:

  1. Exercise-Associated Muscle Cramps (EAMC)

  2. Nocturnal Cramps

As their names suggest, EAMC occur during/post exercise and nocturnal cramps occur, by definition, at nighttime. If the contraction is severe enough it can cause you to enter a state of functional disability or, if nocturnal, sleep disturbance.

What Causes a Cramp?

Although similar in presentation, the cause of both EAMC and nocturnal cramps differ.

Unfortunately, the exact cause of a cramp is not fully understood but there are a number of hypothesis for both EAMC and nocturnal cramps as outlined below.

What Causes Exercise-Associated Muscle Cramps (EAMC)?

Potential causes of EAMC include:

  • Overuse that fatigues the affected muscle and reduces fibre lengthening between contractions.

  • Altered neuromuscular control .

  • Dehydration and altered electrolyte imbalance secondary to extensive sweating. This may be the primary cause or contribute to causing your cramps.

  • Incomplete recovery from a previous episode of cramping.

  • If resting muscle length is short, the muscle can be predisposed to cramping. This can be exacerbated by a fatigued muscle.

  • Electrolyte loss through sweating during exercise can cause the onset of EAMC.

  • Pregnancy.

What Causes Nocturnal Cramps?

Potential causes of Nocturnal Cramps include:

  • Dehydration from chronic insufficient fluid intake or aberrant drinking behaviour with voluntary dehydration - drinking too many glasses of wine!

  • Electrolyte imbalances (low magnesium, calcium or potassium etc.) .

  • Short resting muscle length.

  • Poor blood circulation.

  • Pregnancy.

Other Causes of Cramps

Leg cramps that occur during daily activities and also during the nighttime should be investigated in a bit more detail to rule out the following medical conditions:

  • Peripheral vascular disease.

  • Uremia - raised levels of urea and other nitrogenous waste in the blood.

  • Diabetes.

  • Thyroid dysfunction.

  • Alpha motor neuron disorders.

Medications that Cause Cramps

Finally, some medications can induce cramping such as, but not limited to: diuretics, calcium channel blockers - such as nifedipine, long-acting ß2-agonists, steroids, lithium, statins, cimetidine.

NOTE: if you are concerned that your medication may be causing cramps please consult your doctor or pharmacist.

What to do When You Cramp

If you experience a cramp, the quickest way to relieve it is to stretch it out - i.e. if you get a cramp in your calf, stretch your calf by pulling your toes towards your knee. There is some evidence showing that drinking a highly salty drink (e.g. pickle juice) can relieve a cramp. Finally, it sounds simple but moves out of the position that caused you to cramp.

If cramps are a regular occurrence for you, see one of our physiotherapists for a stretching routine that will ease the cramp when it comes on but also prevent it from occurring.

How to Prevent a Cramp

Taking the aforementioned causes of cramps into account, steps can be taken to prevent the onset of a cramp:

  • Drink plenty of water - 2L a day should suffice, and decreased coffee and/or alcohol consumption.

  • Stretch regularly - particularly your calves, hamstrings, gluteals, quadriceps.

  • Magnesium supplementation or if you know you are low in other electrolytes, take the respective electrolyte supplementation accordingly. We recommend you do this through your doctor or pharmacists guidance.

  • Warm up thoroughly and stay hydrated BEFORE and throughout your exercise - water or a sports drink is useful in this instance.

Treatment for Cramps

The first and foremost priority of treatment for cramps is identifying the root cause of your cramps. Whether this be tight muscles, over-exercising or a cause that requires further investigation. Our physiotherapists are experienced in finding out what it is that is causing your cramps and will point you in the right direction.

Depending on what our physiotherapists find, treatment may involve:

  • Lengthening of hypertonic muscles.

  • Restoring joint range of motion.

  • Strengthening weak muscles.

  • Lifestyle modifications:

    • Fluid intake.

    • Reducing coffee/alcohol intake.

    • Vitamin/electrolyte balancing.

  • Modifying current exercise regimes.

Investigating the Cause of Your Cramps

At PhysioWorks, we work closely with our dietitians and we would often refer our patients to them if we believe the cause of your cramps is a diet/lifestyle origin. 

It is always helpful to seek the advice of your doctor regarding repeated episodes of cramps. They may organise further assessment eg ultrasound, MRI, blood tests etc.

If you have any further question please ask your practioner.