Rating Thirst-Quenching Sports Drinks

Sports-drink manufacturers have made a science of finding just the right concoction to replenish bodily fluids lost during exercise. Most sports drinks consist of water, carbohydrates in the form of sugar, and small amounts of electrolytes, which are minerals such as sodium and potassium that encourage quick replenishment of fluids lost during exercise.

Manufacturers often claim that their special balance of carbohydrates and sodium will stimulate you to drink a lot of fluids, help you to absorb fluids and provide an energy boost.

Sports drinks fall into two main categories:

• High-carbohydrate sports drinks. These usually contain at least 10 percent carbohydrates. These are meant to be used before, not during, exercise.

• Thirst-quenching and hydrating sports drinks. These are meant to be used during and after exercise. These usually contain 4 to 9 percent carbohydrates, making them low-carb drinks. The sodium levels range from 10 to 25 mmol/L, relatively low but safe. These drinks are available in carbonated and non-carbonated forms, and caffeinated and caffeine-free forms. Factors to consider

Factors to consider

When weighing which drink to buy, keep these factors in mind:

• Brand for brand, there's not much difference among the sports drinks available in terms of their ability to quench your thirst or rehydrate you.

• Sports drinks may improve performance in both intermittent and continuing moderate- to high-intensity sports. The benefits are greatest for trained athletes and less so for recreational exercisers.

• If you are thinking of buying a high-carb drink, you should know that drinks with 8 percent or more carbohydrates may slow down your digestive process. Your stomach may feel increasingly full, but you won't get the benefits of rehydration.

• Drinks containing a high level of carbohydrates may cause gas, bloating, or cramps.

• The caffeine in sports drinks doesn't appear to interfere with the drinks' ability to rehydrate. Nevertheless, you may want to avoid drinking multiple caffeinated beverages as you replenish fluids lost during exercise.

• The flavor of the drink and how much sodium it contains may affect how much fluid you drink.

• So-called "fitness waters" can help with hydration, but these drinks don't contain enough carbohydrates to help with exercise endurance.

Avoid giving children sports drinks because the ratio of sodium and glucose in them affects how quickly children will absorb fluids.