Exercise Associated Muscle Cramps

Muscle cramps are still a mystery, since we don’t yet fully know their pathophysiology.

Currently, there are two schools of thought:

➡️ Cramps are caused by losses of fluid and electrolytes through perspiration, especially at high temperatures. However, the plasma characteristics of people prone to cramps are comparable to those that don't experience cramp, and within normal physiological parameters. Furthermore, since these losses are systemic, cramps should be present throughout the body, and stretching should not be a useful strategy.

➡️ Cramps could also be caused by impaired communication between the brain and muscles. In fact, some of the most important risk factors for cramps are fatigue, poor neuromuscular conditioning, and high-intensity exercise. This however, is only one of the possible causes of cramp. Below is a diagram showing the possible intrinsic and extrinsic factors that contribute to the onset of cramp (EAMC):

 

 Some treatment ideas from research include:

  • Stretching is the still the fastest, safest, and most effective treatment and is thought to balance excitatory and inhibitory signals in the muscle.
  • Rehydration restores plasma volume, but is action is slow – 13+ minutes to reach the bloodstream.
  • Anecdotal evidence shows strong flavors (e.g. pickle juice) may stimulate receptors in the digestive system and affect neural function.
  • Bananas are considered effective because of high potassium content, but changes are seen only 1 hour after ingestion.

Recent research has focused more on prevention, some strategies include:

  • Carbohydrate electrolyte drinks may delay fatigue by restoring glycogen reserves, but they haven’t shown any significant effect on EAMC
  • Try assessing sweat losses during exercise, and make sure you fuel adequately to avoid excess fatigue.
  • Prophylactic stretching unlikely reduces the muscle’s excitability. Exercise and neuromuscular retraining protocols show promising results, however – even just for 20minutes a day

EAMC is a complex event with multifactorial causes. A personalized approach based on a thorough assessment of the athlete and their risk factors is required. 

References:

Miller, K. C., Stone, M. S., Huxel, K. C., & Edwards, J. E. (2010). Exercise-associated muscle cramps: causes, treatment, and prevention. Sports health, 2(4), 279-283.

Miller, K. C., McDermott, B. P., Yeargin, S. W., Fiol, A., & Schwellnus, M. P. (2022). An evidence-based review of the pathophysiology, treatment, and prevention of Exercise-Associated muscle cramps. Journal of athletic training, 57(1), 5-15.

Fabrizio Mancini @thephyziotherapist

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