Electrolytes are nutrients that affect fluid balance in the body and are necessary for our nerves and muscles to function. Sodium and potassium are the two electrolytes most often added to sports drinks. Generally, electrolyte replacement is not needed during short bursts of exercise since sweat is approximately 99% water and less than 1% electrolytes. Water, in combination with a well-balanced diet, will restore normal fluid and electrolyte levels in the body. Replacing electrolytes may be beneficial during continuous activity of longer than 2 hours, especially in a hot environment.