Muscular cramping may occur after one to two hours of exercise. Cramping may be induced in as little as 10 minutes after high intensity exercise targeting a specific muscle group.
The most commonly proposed causes of exercise associated muscle cramps (EAMC):
- Decreases in body mass, blood and plasma volume
- Abnormal serum electrolyte concentrations
- Decrease concentrations of sodium, potassium, magnesium, chloride, and/or calcium
- As a result of sweating or over consumption of water during exercise
- Environmental stress
- Exercising in heat which may result in electrolyte imbalances and dehydration
Although it is commonly assumed that cramps during exercise are the result of fluid electrolyte imbalance induced by sweating, studies have not supported this theory (Miles & Clarkson 1994). Dehydration and electrolyte loss are not the sole causes of EAMC because many individuals can experience cramping when they are hydrated and supplemented with electrolytes. Garrison (2012) conducted a meta analysis and failed to find evidence that Magnesium supplementation was effective in reducing cramps.
A more recent theory suggests that EAMC is related to sustained neural activity that results in fatigue. This idea is supported by athletes who are more likely to experience cramps toward the end of an event. A distinction has been made between EAMC that result from fatigue and that resulting from heat (in which electrolyte and fluid losses result in a contraction of extracellular fluid space).
In one study, participants who experienced cramps had a higher average sweat rate than those that did not experience cramps. Subjects who experienced EAMC who consumed a carbohydrate - electrolyte beverage were able to exercise 150% longer before the onset of cramps.
Other common treatments include:
- Salt tablets
- Pickle juice and mustard (anecdotal remedies)
- Saline solution use reported as early as 1898
Garrison SR1, Allan GM, Sekhon RK, Musini VM, Khan KM (2012). Magnesium for skeletal muscle cramps. Cochrane Database Syst Rev. 12;9.
Jung AP, Bishop PA, Al-Nawwas A, Dale RB (2005). Influence of Hydration and Electrolyte Supplementation on Incidence and Time to Onset of Exercise-Associated Muscle Cramps. Journal of Athletic Training. 40(2): 71-75.
Miles MP1, Clarkson PM (1994). Exercise-induced muscle pain, soreness, and cramps. J Sports Med Phys Fitness. 34(3):203-16.