Muscle Cramps and How to Reduce Your Risk

muscle cramps
By Andrew Hall, AccSD.


What is a muscle cramp

A muscle cramp is a sudden, involuntary, painful contraction of a muscle. These symptoms typically ease off within minutes but are often accompanied by a palpable knotting of the muscle. Muscle cramps generally occur in the site most directly involved in the exercise task (most commonly the calf muscle, but they can occur in any muscle). The correct terminology is actually exercise associated muscle cramp (EAMC) as this helps distinguish them from other muscle cramp causes.

When it comes to EAMC, the most frustrating thing is that once they start occurring during your event, it’s very hard to completely shake them!


What causes muscle cramps

There have been many theories to why muscle cramps occur during exercise. Some common ones include: tight or inflexible muscles, poor physical condition, inadequate diet, physical overexertion, hot and humid conditions, heavy sweating, and dehydration. However, most scientists now agree the primary cause of EAMC is altered neuromuscular function (i.e. a physiological process involving both the nerves and muscle) as a result of fatigue in the exercised muscle.

Exercise can cause an abnormal stimulation of the muscle, causing an involuntary and forceful contraction, which is more likely to occur in tired muscles and/or one already in a shortened position. Basically the body’s normal ability to ‘turn off’ a contraction malfunctions, causing it to remain ‘turned on’ (with legitimate discomfort felt by the athlete). This information makes it hard for individuals to actively prevent EAMC however there are some things that can be done to reduce the risk.


What you can control to minimise your risk


Let’s start with fuelling, because there are a few things to consider. As always, seeing an Accredited Sports Dietitian (AccSD) and getting a personalised training plan and a race nutrition plan is one of the best things you can do to help avoid a cramp. The right nutrition allows you to maximise training adaptations, but also builds confidence that your nutritional needs are taken care of, which means one less stress on the day. Less nervous energy being burned = more energy to propel you towards the finish line in personal best time.

What you eat and drink during your training sessions plays a big part in the way your body handles fuelling on race days. It allows your body to adapt at a cellular level and become more efficient at absorbing, storing and using certain nutrients (especially carbohydrate).

You have almost undoubtedly heard the phrase carbohydrate loading thrown around before race day. Often when people hear this they think a huge meal of pasta the night before will do the trick, but there is a little more ground work which needs to be done for the pasta to be most effective. If you fuel your training a certain way (e.g. with accidental or deliberate low carbohydrate availability) and then change the way you fuel on race day (e.g. with high carbohydrate availability), your body does not have the same capacity to utilise the extra fuel (but that’s another whole article!).

Always practise your specific fuelling strategies (both food and fluids) during training. If you get to the race day and find you can’t tolerate a certain product (or amount) and consequently start to fall behind in your fuelling schedule, it’s very difficult to catch up, and consequently you are setting yourself up for earlier onset of fatigue and as a result, muscle cramps.



It is commonly stated that dehydration leads to poor performance, and while this is still true to some extent, the guidelines around hydration and EAMC have somewhat changed in the past few years. During exercise, the minerals required by the nervous system for muscular contraction/relaxation can be distorted.

Simply put, during sweating the body loses fluid and electrolytes (mostly sodium) and, if these are not replaced appropriately can cause an imbalance within the body. There’s not a general guideline for fluid and electrolyte prescription – each person has highly individualised needs.

By working with an AccSD you can establish your individual sweat rate, as well as the amount of sodium lost in your sweat. It’s then possible to effectively match your sodium and fluid intake during the race to your specific needs. It’s also important to determine which fluid will be most suitable for you. Consider whether or not the fluid provides; water alone; water plus electrolytes, or water plus electrolytes plus carbohydrates. All are suitable options, but their use will depend on your training and body composition goals.



There are many sports drinks and electrolyte drinks on the market with various combinations of water, carbohydrate, and an assortment of minerals (sodium, potassium, magnesium and calcium are common additions). However, recent research has revealed that abnormal blood levels of potassium, magnesium or calcium do not cause muscle cramps. While some athletes will incur large losses of sodium during sport due to a high concentration of sodium in their sweat and/or high sweat losses, the evidence that this can lead to cramps is inconclusive.



Cramps are less common in athletes who are well trained and appropriately conditioned for the event they are competing in. Cramps are more common on race day as it’s during this time that the body is pushed to limits higher than before.

There is a good theoretical basis for performing exercises that target the neuromuscular system to reduce risk of EAMC. Moreover, it may be beneficial to complete specific exercises that target muscle spindle and golgi tendon organ receptors. This should be implemented to delay neuromuscular fatigue onset and, resultantly, EAMC. Plyometric exercises may also be beneficial to promote neural adaptations in muscle spindle and golgi tendon organ receptor firing, enhancing efficiency and sensitivity of reflexive and descending pathways used for neuromuscular control.

Understandably, specific endurance training can serve as an effective way of reducing EAMC risk by expanding plasma volume and the extracellular fluid compartment and delaying neuromuscular fatigue. For help with your training and conditioning plan, get in touch with our friends at ESSA or ASCA.


As always, more research needs to be completed in this area. But if you’re serious about avoiding muscle cramps, book an appointment with an AccSD – you sure will be thanking them when you get to the finish line cramp-free!