Athletic development specialists dedicated to the art and science of excellence in movement

Exploring Causes of Exercise Associated Muscle Cramps: Part II

As intense summer heat engulfs the nation, many athletes complain of muscle cramps.  This post is a sequel to previous posts reviewing the literature in this area. 

Exploring Causes of Exercise Associated Muscle Cramps

Concepts for Hot Weather Training

Traditional thought is that electrolytes will help cure exercise associated muscle cramps.  Not sure exactly where this thinking began (likely sport drink companies?), but this explanation persists despite a definite lack of evidence in the peer reviewed literature.   As we discussed in the other posts, other factors (especially fatigue, mechanics, and even mental state) DO have evidence supporting a link to muscle cramps.

Popular understanding of cramps involves anecdote and folklore.  And that’s not surprising…it’s hard to intentionally dehydrate people in controlled environment due to ethical and legal considerations.  We’re left mostly with anecdote and field studies, which have the advantage of being in the field, but harder to reach causation.  In races, athletes are both tired and dehydrated, making it nearly impossible to assess fatigue and hydration independently. 

Further, as we noted previously, one reason why athletes adopt the dehydration theory is that it’s easier on the ego to blame an electrolyte imbalance versus poor strategy or muscle weakness. Know that the evidence does not support electrolyte balance as an antidote to cramping.  Listen with a critical ear if some person or some company tries to sell you on electrolytes as a cramping antidote.      

However, one recent study (Miller 2010) did attempt controlled dehydration.  Authors began…

“The theory states that dehydration contracts the interstitial space, thereby increasing the pressure on nerve terminals and cramps ensue. Research supporting this theory is often observational, and fatigue is rarely controlled. Inducing cramps with electrical stimulation minimizes many of the confounding factors associated with exercise-induced cramps(e.g., fatigue, metabolites). Thus, our goal was to minimize fatigue and determine whether hypohydration decreases the electrical stimuli required to elicit cramping (termed "threshold frequency").”

Essentially, the protocol was to take severe muscle fatigue and other factors out of the equation and see if muscles were more sensitive to an electrically induced cramp in a dehydrated state versus a non-dehydrated state.  Authors had ten male subjects cycle for thirty minute periods until they lost 3% of body mass.  They induced muscle cramps with electric stimulation in both a hydrated and dehydrated state, and then tested the level of stimuli needed to elicit a cramp.  Subjects repeated the experiment one week later.    

Results: “Mild hypohydration (water loss) with minimal neuromuscular fatigue did not affect threshold frequency.  Mild hypohydration with minimal neuromuscular fatigue does not seem to predispose individuals to cramping.  Thus, cramps may be more associated with neuromuscular fatigue than dehydration/electrolyte losses.”

Authors do concede that the data is unproven for extreme dehydration.  However, this study does add to the mounting evidence against electrolytes (or lack thereof) as the cause of exercise associated cramps. 

My opinion: If you have a strategy that works, then keep doing what you are doing.  But if cramps are a persistent problem, consider factors outside hydration that have a more robust basis in evidence.


Miller KC, Mack GW, Knight KL, Hopkins JT, Draper DO, Fields PJ, Hunter I.  Three percent hypohydration does not affect threshold frequency of electrically induced cramps. Med Sci Sports Exerc. 2010 Nov;42(11):2056-63.


Thanks for the post! I myself

Thanks for the post! I myself have always wondered the best way to avoid the muscle cramps. I get them even when I stretch before and after!

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