Keeping Hydrated

After 90 minutes of exercise, or 30 minutes of exercise or activity in extreme conditions, the body begins to lose electrolytes, which must be replaced. Electrolyte replacement is extremely important to endurance athletes, like marathoners, who are at risk of hyponatremia or "over hydrating."

Hyponatremia can occur when an athlete drinks too much water, which fails to replace lost sodium and causes sodium levels to drop to dangerously low levels. For more information, visit Hyponatremia a Concern for Marathon Runners.

The best way to avoid hyponatremia and dehydration during prolonged exercise is to increase salt intake and consume a sports drinks containing electrolytes like sodium and potassium and carbohydrates that re-fuel muscles.

For maximum hydration:

•Drink water for the first 90 minutes of activity, then switch to a sports drink or if exercising in extreme heat or cold, switch to a sports drink after 30 minutes.

•Weigh yourself before and after exercise, then consume 6 ounces of fluid every 15 minutes until your weight has returned to normal.

•Drink 8 to 10 ounces of a sports drink every two hours. Frequent sipping will help prevent an upset stomach and maximize electrolyte absorption.

•Between servings, drink water. In fact, dentists recommend rinsing your mouth out after drinking a sports drink to help prevent the sugar and acid from causing dental cavities.

•Snack on salty foods.

Choosing a Sports Drink
When compared to one another, most sports drinks are formulated with similar percentages of electrolytes and carbohydrates. This means that taste, tolerability and price become the most important factors in choosing one.

Following are examples of electrolyte replacement drinks that, per 8 ounce serving, contain correct amounts of carbohydrates and electrolytes.

•Gatorade
•PowerAde
•Exceed
•AllSport
•Hydra Fuel
•Cytomax
•Endura
•10K
•Breakthrough

Be Warned consumers to beware of drinks marketed for athletes that are not electrolyte drinks. Beverages to watch out for are vitamin fortified drinks, such as Propel Fitness Water, Glaceau VitaminWater and energy drinks like Red Bull, RockStar, etc.