The Role of Dehydration and Electrolyte Loss on Exercise-Associated Muscle Cramps

Abstract

1241 Dehydration, electrolyte imbalance, environmental stress, and neuromuscular fatigue have all been implicated as potential causes of exercise-associated muscle cramps (EAMC). Additionally, maintenance of fluid and electrolyte balance is often prescribed in the prevention of EAMC. However, there is little scientific data to support these assertions. PURPOSE: To determine the role of hydration and electrolyte balance in the prevention of EAMC. METHODS: Thirteen, college-aged males each completed two counter-balanced trials in a repeated-measures design. In each trial, participants performed a calf-fatiguing protocol known to induce EAMC in the calf muscle group. Each trial was performed in the same hot environment (dry bulb = 37 C, relative humidity = 60%). Participants consumed a carbohydrate-electrolyte beverage two hours and 30 minutes prior to each trial in order to optimize hydration and electrolyte levels. In one trial (euhydrated), participants consumed a carbohydrate-electrolyte beverage (with 3.0g NaCl added per liter of fluid) at a rate similar to sweat loss. In a second trial (hypohydrated), subjects were not allowed to consume any fluids. RESULTS: Cramps were induced in nine of the participants, while seven participants cramped in both trials. For those who cramped in both trials exercise duration prior to the onset of EAMC was significantly longer in the euhydrated trial (36.8 ± 17.3 minutes) compared to the hypohydrated trial (14.6 ± 5.0 minutes; p < .01). Mean weight loss for the hypohydrated trial was 1.0% ± 0.4% of body mass. No weight loss occurred during the euhydrated trial. CONCLUSIONS: The results suggest that dehydration and electrolyte loss are not the singular cause(s) of EAMC, since subjects cramped when they were euhydrated and in electrolyte balance. However, it appears that consumption of a carbohydrate-electrolyte beverage prior to and during exercise in a hot environment may delay the onset of EAMC.