Are Muscles Cramping Your Performance?

Are Muscles Cramping Your Performance?

Defined as ‘painful involuntary skeletal muscle contractions’, muscle cramping is a common and unwelcomed complaint among many athletes.

Exercise related muscle cramps (ERMC) typically occur in athletes who compete in long distance endurance events, multi-day events and high intensity sports including triathlon, marathon, footy, cycling and tennis. Muscle groups where cramps occur are usually in the quads, hamstring and most commonly the calf.

Despite how common cramping is, evidence is mixed as to how cramps occur and how to prevent them. ERMC has been attributed to dehydration, electrolyte imbalance and heat as well as untrained endurance fitness, high BMI, shorter daily stretching time and/or genetics.

Most scientists however agree that the primary cause of EAMC is muscle fatigue and altered neuromuscular function. This causes an abnormal stimulation of the muscle and autonomic (just happens) muscle contraction. Ouch!

To provide nutritional strategies to assist in decreasing the likelihood of cramping we  therefore take a multifactorial approach in aiming to decrease muscle fatigue.


Carbohydrate is stored in the muscle as glycogen and is the preferred fuel of the body for exercise. When exercising at a high intensity and even more importantly during exercise lasting over 90 minutes, the body needs carbohydrate to perform maximal efforts.

TIP: small carbohydrate-based snack 1hr prior to exercise such as fruit or ½ English muffin plus additional hits each hour (fruit, gels, lollies) will provide energy to help prevent premature muscle fatigue and cramps.

The theory of dehydration is a common explanation for why muscle cramping occurs. Physiologically dehydration results in greater cardiac stress and work output. There is little evidence which directly associates muscle cramping to dehydration. However, what we do know is that losing 2% or more in body weight fluid during long or high-intensity exercise is a recipe for decreased concentration and performance. Therefore appropriate fluid intake before, during and after exercise will decrease muscular fatigue and the likelihood of cramps. Sweat rate loss varies amongst individuals so if you are prone to cramps it is a good idea to measure your sweat rate and speak to a Dietitian about an individualised hydration plan.

Ensure you are hydrated BEFORE exercising. An easy way to tell is to just aim for clear-light yellow urine.
Drink regularly. 100-200ml every 15min increases absorption of fluid.
Consume and electrolyte formula or sports drink during long and intense events or games.


The fluid we sweat not only removes water from our bodies, but also electrolytes including sodium, chloride, potassium and magnesium. Electrolytes play a part in muscle contraction/relaxation and nerve transmission, so any interruption to this balance could lead to complications. Some studies have found ‘salty sweaters’ cramp more often, however literature is inconclusive. Athletes who have a high salt sweat concentration often benefit from an individual salt replacement strategy during events. Sweat rate and sweat sodium concentration do vary based on duration, intensity and environment so it’s a good idea to be tested under conditions similar to race/event day.

Salty carb snacks such as pretzels may encourage fluid intake before exercising for long periods of time.
A pinch of salt in your sports drink may assist however doesn’t taste fantastic.
It has been suggested that a LOW salt intake away from exercising may decrease the concentration of salt in sweat – meaning perhaps less need to replace large amounts during exercise.


Quinine has been used to treat cramp frequency and intensity however can be dangerous and even lead to fatality in large doses.

Magnesium is often used to prevent recurrent cramping. Some people respond, others do not. A diet rich in leafy greens, legumes, seafood (tuna, salmon) and wholegrains will ensure adequate magnesium stores in most people.

A small ‘shot’ (30-60ml) of Pickle Juice swished around in your mouth, has been found to relieve cramps within 35 seconds. Its speculated that pickle juice triggers a reflex which inhibits neuromuscular activity in cramping muscles.


With multiple theories on how muscle cramps occur, there is no single answer for relieving or preventing cramps.

Prevention strategies away from nutrition include;

  1. Stopping exercise at the onset of the cramp
  2. Being adequately trained for your event or sport
  3. Massage therapy
  4. Heat acclimatisation
  5. Active and passive stretching


Top tips nutritionally to decrease cramping include;

  1. Being well fuelled before exercise (adequate carbs and muscle glycogen stores)
  2. Hydrate before, during and after exercise
  3. Consider salt replacement strategies
  4. Trial supps which are not likely to be a danger to health including magnesium (diet adequacy before supps) and pickle juice (at the time of cramping).

If cramping is ongoing and debilitating to your performance, see your Dietitian for an individually considered nutrition and hydration cramping strategy.