THE EFFECTS OF HYPERTONIC, ISOTONIC, AND HYPOTONIC BEVERAGES ON REHYDRATION AFTER EXERCISE: A REVIEW

Abstract

Rehydration depends on the rate of gastric emptying, intestinal absorption and fluid retention after fluid consumption. The increased rate of gastric emptying and intestinal absorption that occurs with hypotonic beverage consumption provides an advantage in rapid rehydration, but results in increased urine production, which can cause a return to negative fluid balances over time. Isotonic beverages provide an advantage over hypotonic and hypertonic beverages, as they are rapidly absorbed, but do not cause diuresis due to their increased electrolyte and/or carbohydrate concentration. Hypertonic beverages can hinder rehydration due to their decreased rate of gastric emptying and intestinal absorption. However, they prevent urine production and thus aid in long-term rehydration compared to hypotonic and isotonic beverages. Athletes should select beverages based on their hydration needs and the type of activity performed.