Recognizing And Preventing Dehydration In Athletes

By Mark A. Caselli, DPM, and John Brummer, DPM

   A simple method to determine hydration status is to compare urine color (from a sample container) with a urine color chart. A light “straw” color (1 or 2) is indicative of being well hydrated while a dark color (5 or 6) represents significant dehydration. Measuring urine specific gravity with a refractometer is less subjective than comparing urine color and can also be used. For color analysis or specific gravity, midstream urine should be collected for consistency and accuracy. Since body weight changes during exercise give the best indication of hydration status, one should determine an athlete’s weight and urine measurement before the exercise session and then determine their weight after exercise to estimate fluid balance.

   All athletes participating in sports requiring weight classes such as wrestling or rowing should have their hydration status checked at weigh-in to ensure they are not dehydrated. A urine specific gravity less than or equal to 1.020 or urine color less than or equal to 4 should be the upper range of acceptable on weigh-in. Procedures such as taking diuretics, exercising in rubber suits or in a sauna to reduce body weight can produce dramatic dehydration.

Pearls On Preventing Dehydration

   The best way to prevent dehydration is to establish a good hydration protocol for the athletes. Fluid replacement beverages should be easily accessible in individual fluid containers. Individual containers make it easier to monitor the athlete’s fluid intake. The containers should also be marked in 100 ml or in 3- or 4 oz. increments, providing visual reminders to athletes to drink beyond thirst satiation. When it is practical to do so, carrying fluid bottles during exercise encourages greater fluid ingestion.

   To ensure proper pre-exercise hydration, the adult athlete should consume approximately 16 to 20 fl. oz. of water or sports drink two to three hours before exercise and 8 to 10 oz. of water or sports drink 10 to 20 minutes before exercise. Adjust fluid intake for children for differences in body weight and physiology (see “Recommendations For Fluid Intake For Children” below). Fluid replacement should approximate sweat and urine losses, and at least maintain hydration at less than 2 percent body weight reduction. This generally requires 8 to 10 fl. oz. every 15 to 20 minutes of rigorous exercise.

   Post-exercise hydration should aim to correct any fluid loss resulting from the practice or event. One should ideally complete rehydration within two hours with a fluid that contains water to restore hydration status, carbohydrates to replenish glycogen stores and electrolytes to speed rehydration. The primary goal is the immediate return of physiologic function. When rehydration must be rapid, as in cases where an exercise bout will follow, an athlete should drink about 25 to 50 percent more than sweat losses to assure optimal hydration four to six hours after the event.

   The type and temperature of the fluids used in a sporting event are important in the promotion of the rehydration process. This is especially true in events that involve children and adolescents. One should ensure the most palatable beverage possible is available.

   Sports drinks appear to outperform water in preventing dehydration, especially in young athletes. A study that offered water, flavored water and a sports drink to active children ages 9 to 12 showed they drank 90 percent more of the sports drink and stayed better hydrated than when drinking plain water. Sports drinks served cold (50º to 59ºF is recommended) have flavor (sweetness) and sodium that encourage athletes to drink more.

   When fluids have the correct mixture of carbohydrates and electrolytes, athletes absorb them quicker into the bloodstream and the fluids help refuel muscles and speed rehydration. Carbohydrates also aid in performance by facilitating an increased feel of energy for power and endurance enhancement. Though carbohydrate concentrations greater than 8 percent increase the rate of carbohydrate delivered to the body, they compromise the rate of fluid emptying from the stomach and absorbed from the intestine.

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