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So what exactly is cramp?

According to the ‘Urban dictionary’, ‘Cramp is a god-awful pain when your body is saying “AW HELL NO” in a certain area.'

Technically, exercise associated muscle cramps (EAMC) are when a muscle gets tight (contracts) without you trying to tighten it, and it does not relax. Cramps may involve all or part of one or more muscles. The most commonly involved muscle groups are:

  • Back of the lower leg/calf
  • Back of the thigh (hamstrings)
  • Front of the thigh (quadriceps) (Grove A J 2014)

When do muscle cramps usually occur?

Latter stages of a training session or competition, though some athletes often complain of EAMC symptoms up to 8 hours after exercise. This post exercise period of increased susceptibility to EAMC has been termed the cramp prone state. (Schwellnus M 1997). Cramps tend to affect endurance athletes more frequently but any kind of exercise which involves activation of muscle and nerve fibres can lead to cramping whether you’re exercising for 4 hours or 40 minutes. Other factors which can influence a person’s susceptibility to cramps include:

  • GENDER: Men tend to be more susceptible than women.
  • AGE: As age increases so does the likelihood of experiencing muscle cramps
  • MEDICATION: Use of some medications including statins, beta blockers, blood pressure medication and even the oral contraceptive pill can increase the chance of muscle cramps occurring.

Does anyone really know the cause of muscle cramps?

Many experts will confidently tell you exactly why you’re experiencing muscle cramps… ‘your dehydrated, you’re not fit enough, you need more electrolytes or sodium (salt), you don’t stretch enough, you’re glycogen depleted, you don’t eat enough protein, you need more calcium in your diet.... want me to go on? Truth is:  little is known about the true cause of muscle cramps. This in part is due to a lack of strong experimental evidence for any theory and cramps are difficult to study due to their unpredictable, random nature. Secondly, research has suggested that there may be different kinds of EAMC and thus different causes. Clear as mud?

So what do we know?

EAMC are likely due to several factors and discovering a strategy that resolves or reduces the intensity and frequency of attacks should be addressed on an individual basis using a process of elimination. What should that process be? Try one strategy at a time in a consistent strategic way. The following protocol may help you nail the cause.

Dehydration – electrolyte/mineral imbalance?

Most incidences of cramping occur during the warmer summer months. A time when you’re most likely to sweat more, but also a time that most people actively engage in exercise at higher intensities. This however does not account for those who experience cramp when the weathers cooler. Despite this, the loss of water and electrolytes through sweating is still seen as a potential contributor to the occurrence of cramps.

Fluid Replacement

A Simple cure could be Fluid Replacement. Do the sweat test, weigh yourself prior to exercise and again after. If there’s a difference in weight, it’s likely due to fluid losses. 1kg loss equates to a litre of lost fluids mostly through sweat. Measure this over a period of a few days to get a base line and begin replacing those fluids during exercise so when you return from training, weight losses are negligible.

Electrolyte Replacement

Still cramping... add some electrolytes to your water using an isotonic drink (the same concentration as body fluids), these provide you with sodium, magnesium, potassium and chloride and energy as well as optimising fluid replacement.  New technology means you can track how much sodium you’re actually losing during a workout using a ‘sodium test’. What you get from a sweat test is a highly accurate reading of the level of sodium (the key electrolyte lost in sweat) that you are losing during exercise. You may wish to include a mineral or salt rich snack prior to exercise too such as.

Glycogen depletion

Still cramping, ensure you’re glycogen stores are not depleted, (stored carbohydrate in muscles and liver). This can be achieved by ensuring you eat a carbohydrate rich meal or snack prior to exercise and during exercise if longer than 60-90 minutes or by using a good quality glucose polymer sports drink mixed to a 6% solution. This is equal to 60g per 1000ml of water.

Still suffering?

Consult with an exercise physiologist. Not all cases of cramp are due to dietary issues. Poor body mechanics, inadequate preparation and a lack of overall fitness have all been suggested as contributing or causative factors for cramps.

 Enjoyed this article? For more nutrition and exercise related articles visit our blog.


This article was written by Science Fitness in-house Dietitian and former pro-cyclist Danielle Davies.

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