Hecker, A. L., & Wheeler, K. B. (1994). Impact of hydration and energy intake on performance. The Journal of the National Athletic Trainers Association, 19, 4-9.

Sodium and chloride are the primary electrolytes lost in sweat because of their higher concentration in circulating blood. Potassium, magnesium, and calcium concentrations are smaller because they primarily are located in the cells. Under most conditions, electrolyte replacement is not necessary and can actually hinder performance. Although electrolyte loss in sweat increases with exercise, water loss is larger. Thus, electrolytes (e.g., sodium) actually increase in concentration and so excessive salt intake causes an even greater concentration.

Normal dietary habits are usually sufficient to replace electrolyte losses during moderate dehydration.

However, when individuals are exposed to daily 5-6% body weight fluid losses, there is the risk of an electrolyte deficit occurring. Under such conditions, small amounts of electrolytes should be consumed during physical activity. The ACSM recommends: (a) 218 mg of sodium, (b) 337 mg of chloride, and (c) 183 mg of potassium per quart of water.

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