What can I do to reduce risk of cramp?

Exercise-associated muscle cramps (EAMC) are a frustrating and painful experience. Most runners can run through a mild cramp, however in severe cases cramps can result in a DNF. There is significant confusion and you’ll likely be offered many prevention and treatment strategies by your running buddies. This blog explores the research regarding the proposed mechanism of EAMC, potential contributing factors, and management options.

What are exercise-associated muscle cramps?

EAMC are sudden and involuntary contractions of one or more muscles that occurs during or after exercise. These cramps affect the exercising muscles and can range in severity from mild, not affecting performance, to severe, requiring medical attention. 30-50% of marathon runners experience EAMC. They are more common among less experienced and older runners, those running at a faster pace than usual, and during exercise in the heat.

What causes muscle cramps?

There are different ideas about why EAMC happen. One theory is that they occur because of dehydration and a lack of electrolytes in the body. However, this theory has not been proven by scientific studies. Another theory is that muscle cramps happen because of fatigue and other factors that affect how the nervous system works. This theory suggests that athletes who are not adequately trained or who exercise at higher intensity than they are used to are at greater risk of cramping. However, well-trained athletes can also get cramps, which means there might be other causes too. A newer theory suggests that many different factors can contribute to EAMC. Each athlete has their own threshold for cramping, and the risk of EAMC increases with the number and severity of these risk factors.

What are possible risk factors for cramp?

The following risk factors are believed to contribute to EAMC via impacts on the central nervous system and neuromuscular control. Exploring your risk factors and developing strategies to address these may help to reduce the risk of cramp.

• Hot and/or humid condition
• Increased exercise duration and/or intensit
• Repetitive muscle exercise
• Muscle injury/damage and/or history of running injuries
• Under-hydration
• Lack of sleep
• Older age
• Decreased muscle energy
• Inadequate conditioning
• Underlying medical condition
• Medications, supplements and dietary stimulants (e.g. caffeine)
• History of cramp during similar exercise sessions
• Stress

What strategies help improve a cramp?

Rest

• Helps to normalise neuromuscular activity.

Pain relief

• Ice therapy, massage and electrical stimulation may provide relief from pain associated with EAMC.

Stretching

• Stretching is the fastest, safest and most effective treatment for cramp. This can be done yourself, or by a health professional.

Rehydration

• Rehydration with a carbohydrate-electrolyte drink can improve hydration however there is a risk of developing low blood sodium (hyponatraemia) if consuming large amounts of sports drinks.

Transient receptor potential agonists

• Transient receptor potential (TRP) receptors present in the gastrointestinal tract are responsible for detecting both temperature and taste sensation. Certain ingredients, such as capsaicin, ginger, vinegar, and cinnamon, are known to activate these receptors and potentially affect neural function if they are potent enough. A single-blind study observed that consuming small amounts of pickle juice helped relieve cramps 45% faster (in 68.6 seconds) than no fluid and 37% faster (in 49.1 seconds) than water. The activation of TRP channels located at the back of the throat is believed to trigger a reflex that can halt cramping sensations by stimulating the nervous system and resetting the nerve pathway to muscles throughout the body. Further research is required to understand this process and other TRP agonists. Nonetheless, considering the negligible risk of harm associated with these ingredients, they are worth considering in cases of cramping.

How do I manage chronic or recurrent cramp?

Once medical problems have been ruled out, a sports physician or sports dietitian can assist in exploring your risk factors for EAMC. While we have learned a lot about the causes of cramps, there is not enough evidence to recommend specific methods to prevent them. A personalized approach should be taken based on an individual's unique risk factors. Factors below are worth consideration by all athletes for optimising performance and reducing risk of EAMC.

Optimise training and fitness

• Set realistic performance goals that are achievable.
• Train at similar intensities and under similar conditions to key events to prepare your body for the demands of the competition.
• Neuromuscular retraining with exercise is a promising strategy for preventing EAMCs. In one study, a triathlete's hamstring EAMCs were eliminated with a short daily at-home protocol over eight months. Examples of these exercise include plyometrics (jumping-style activities) or eccentric exercises (e.g. running down hill).
• Ensure you get enough rest and sleep to support your physical activity.

Optimise nutrition and hydration

• Ensure adequate hydration the day prior to your event
• Use pre-cooling and heat management strategies when exercising in the heat
• Fuel with enough carbohydrates to delay onset of fatigue
• Know your sweat rate and develop a fluid replacement plan to avoid under- or over-hydration

Unproven strategies

• Electrolyte tablets and magnesium supplements have not been found to prevent EAMC.
• While static stretching is useful in treating EAMCs, it is not effective in preventing them.

Summary

In recent years, we have learned more about what causes EAMC. It seems that problems with how our muscles and nerves work, and to a much lesser degree, fluids and electrolytes losses, are the main reasons for EAMC. We have good evidence that resting and gently stretching can help ease EAMC, followed by dealing with the root causes. But we don't have much evidence to show which methods work best to prevent EAMC. A personalized approach should be used to understand your unique risk factors for EAMC to maximise your chances of preventing them so you can perform at your best!

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References

https://www.ais.gov.au/nutrition/supplements/group_b#pickle_juice

Maughan RJ & Shirreffs SM 2019, 'Exercise Associated Muscle Cramp', Sports Science Exchange, vol. 29, no. 200, pp.1-6.

Milller KC et al 2022, An evidence-based review of the pathophysiology, treatment and prevention of exercise-associated muscle cramps', Journal of Athletic Training, vol. 57, iss. 1, pp.5-15.

Schwellnus MP et al 2022, 'Underlying chronic disease, medication use, history of running injuries and being a more experienced runner are independent factors associated with exercise-associated muscle cramping: A cross-sectional study in 15778 distance runners.', Clin J, Sports Medicine, vol. 28, no. 3, pp 289-298.