Sports drinks aren’t necessary for children and teenagers and are likely to contribute to obesity, according to U.S. researchers urging parents to limit consumption of the beverages.

While adolescent athletes engaged in vigorous physical activity may benefit from the carbohydrates and electrolytes provided by drinks such as PepsiCo Inc.’s Gatorade and Coca-Cola Co.’s Powerade, researchers said water should be the beverage of choice for hydration.

"For most children engaging in routine physical activity, plain water is best," Holly J. Benjamin, a co-author of the study published today in Pediatrics, the journal of the American Academy of Pediatrics, said in a statement. "Sports drinks contain extra calories that children don’t need."

Obesity in children and adolescents ages 2 to 19 rose in the U.S. to almost 17 percent in 2007-2008 from 5 percent in 1971-1974, according to the Centers for Disease Control and Prevention in Atlanta. The number of all Americans who are obese has remained constant since then, according to a January study by the CDC. Obesity, which is a measure of body mass index, contributes to higher risk of diabetes, heart attacks and strokes.

Today’s study also focused on the effects of energy drinks that contain caffeine and other stimulants. These beverages can damage children and adolescents’ neurologic and cardiovascular systems and shouldn’t be consumed, said Benjamin, a University of Chicago associate professor of pediatrics and a physician specializing in sports medicine, and Marcie Beth Schneider, a study co-author and a pediatrician in Greenwich, Connecticut, specializing in adolescent medicine.

Caffeine Amounts

Some energy drinks have more than 500 milligrams of caffeine, or the equivalent of 14 cans of soda, Schneider said in a statement. Rockstar, made by Las Vegas-based Rockstar Inc., has 80 mg of caffeine per 8 ounce serving, more than twice the amount in the same-sized serving of Coca-Cola.

About 28 percent of children ages 12 to 14 regularly consume energy drinks, according to a study published in the March issue of Pediatrics.

Energy drink sales totaled $7.7 billion in 2010, an increase of 8.9 percent from the year earlier, according to Beverage Digest, a compiler of data from drink makers and other sources. About $7 billion, a 7.5 percent rise, was spent on sports drinks, which contain carbohydrates, electrolytes and sweeteners.

Learn Differences

The authors recommended physicians educate children and parents on differences between sports and energy drinks and the potential health risks.

"Some kids are drinking energy drinks — containing large amounts of caffeine — when their goal is simply to rehydrate after exercise," Schneider said. "This means they are ingesting large amounts of caffeine and other stimulants, which can be dangerous."

In 2006, Coca-Cola, based in Atlanta, PepsiCo, based in Purchase, New York, and other beverage companies agreed to halt soft-drink sales in elementary and middle schools, according to the American Beverage Association. Sports drinks, diet soda and flavored waters are still sold at high schools. The companies also agreed not to sell energy drinks at schools with kindergarten to 12th grades.

About 88 percent fewer beverage calories were shipped to schools from 2004 to 2009, according to the Washington-based association.

"Sports drinks have a long history of scientific research showing their benefits for hydration," Maureen Storey, senior vice president of science policy for the ABA, said in an e-mail. "As with all food and beverages, they should be consumed in moderation."

Energy drinks "are not intended for young consumers," Storey added.

Coca-Cola and PepsiCo referred requests for comment to the beverage association. Rockstar didn’t respond to a request for comment e-mailed to the company’s general information box.

"If a child or adolescent is already inactive, overweight or obese, then the extra calories in the drink just worsen the weight issue because they can’t burn off what they eat," Benjamin said in an e-mail. "For an active young child that enjoys a Gatorade, sports drink, with sports, it’s likely not a problem, but remember it is a choice then, it’s not needed."