Exercise associated muscle cramps (EAMC) can be quite debilitating during exercise, anyone who has had a cramp before either during exercise or not would agree they can be quite painful. Researchers 1 suggest that the cause is still unclear and has been postulated that it could be several factors combined in the right conditions which induce EAMC. These factors include;
Dehydration – electrolyte imbalance had its limitations due to the level of dehydration and electrolyte loss that caused one individual to cramp was not identical in other individuals. There was no cause and effect relationship from the levels of dehydration and electrolyte loss.
Neuromuscular fatigue when reviewed found that cramps were more likely to occur when the muscle placed into a shorten position - when you bend your leg and your hamstring cramps, the hamstring is in a shortened position. As the muscle fatigues the afferent nerves (the ones that send signals from your muscles to your central nervous system) also fatigue. It is unclear where the neuromuscular fatigue is occurring which could induce a cramp, the peripherally (in the muscle) or centrally. Furthermore, it is suggested that fatigue is essentially a continuum rather than an absolute point.
Treatment methods included; hydration, electrolyte replacement, carbohydrate replacement and stretching. Of all these methods, stretching gave significant relief where hydration, electrolyte replacement and carbohydrate replacement did not provide relief to cramps particularly as it can take up to 13 minutes for the ingested substances to be digested and moved into the blood stream.
So, what should one do about the cramps then? Let’s look at prevention, this is not a concrete solution due to research not finding absolute cause and effect relationships for EAMC however it can provide the best alternative to putting your head in the sand and hoping for the best.
Hydration prior to exercise and as a daily focus, our bodies have approximately 60% of their content from water in adults which should be maintained for optimal function and towards prevention of EAMC and heat stress. Pre-hydration should commence a few hours prior to exercise to allow urine levels to return to normal and with the goal of commencing activity with normal plasma levels. Due to varying sweat rates during activity and individualized hydration program during activity is recommended. You can determine your sweat loss by weighing yourself before and at then end of exercise. During exercise fluid ingestion is suggested to be sufficient to ensure no more than 2% body weight loss after exercise 2. Hydration post exercise looks at returning fluid loss and electrolytes during activity.
Exercise to delay neuromuscular fatigue should be incorporated into your training programs. These are a combination of strengthening the muscles you will be using during your chosen exercise. A combination of eccentric training and plyometrics can be beneficial to improving your bodies ability to withstand neuromuscular fatigue. Complimenting this with a balanced stretching program. These exercises should be undertaken in the correct volumes and at the right times of your strength program, therefore getting an individualized program that progresses you through volumes and frequencies that align with your current level of strength and ability is key.
1. 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. http://doi.org/10.1177/1941738109357299
2. Sawka MN, Burke LM, Eichner ER, Maughan RJ, Montain SJ, Stachenfeld NS. (2007). American College of Sports Medicine position stand. Exercise and fluid replacement. Medicine and Science in Sports and Exercise. 2007 Feb;39(2):377-90.
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