August 6/London/ABC News -- A group of researchers at England's Oxford University published a study of sports drinks' marketing claims and the science behind them in BMJ, the British medical journal.

"We [found] that much of the science has not been well done," Dr. Matthew Thompson, senior clinical scientist at Oxford, told ABC News. "[It] could have easily been done much more rigorously so we'd actually know whether or not these products work."

The Oxford researchers, independent M.D.'s and clinical scientists, looked at more than 400 advertising claims for sports drinks and could not find scientific backing for more than half of them. They characterized many of the rest as flawed science.

 "They've used a lot of industry sponsored scientists to do the research, which makes us suspicious," said Thompson. "There's nothing wrong with having a scientific study funded by a company, and this happens all the time with pharmaceuticals and many products. I think what's key is that the science that is done is of high quality."

Most nationally known nutritionists are critical of sports drinks because most contain sugar, half as much as soft drinks, and have little special benefit for casual athletes who work out less than two hours a day. The nutritionists also say sports drinks should not be routinely given to children.

"The sports drinks are grossly oversold," said Kelley Brownell, director of the Rudd Center for Food Policy and Obesity at Yale University. "Kids all over the place, teenagers are especially drinking these things like crazy when they don't really need them."

The American Beverage Association disputed the claims made by the study.

"Unfortunately, this series of articles exhibits a clear bias by overlooking widely accepted research on sports drinks. The body of available science supports the benefits of sports drinks for carbohydrate energy and hydration, which are necessary for an athlete's overall health, wellness and athletic performance," the association said in a statement. "Our member companies' marketing makes it clear that sports drinks are formulated for athletes and those who are physically active. ... Sports drinks -- which are available in a range of calories -- can also be an option for those who are working out, training, exposed to high temperatures or simply seeking refreshment as part of an active and healthy lifestyle."

Karen Dolins, a sports nutritionist at Columbia University, has been paid what she says is a pittance by Gatorade as a speaker. She says the fact that a company pays for research doesn't automatically mean the research is invalid.

"I think that's also a very important reason we have peer reviewed journals so that there are people who are reviewing the research," she said.

"The sad, sad state of affairs is where else are you going to get research from?" she said. "You're not going to get large NIH grants to study sports nutrition issues. ... [The money from Gatorade] in no way influences what I do and what I say. I'm a professor. I teach sports nutrition and one of the most important pieces that I try to get across with my students is how to actually evaluate the research."

Dolins agreed the average workout doesn't require a sports drink for hydration.

"Are sports drinks appropriate for everyone? Absolutely not. Are they appropriate for some people? Absolutely so. And I think that determination has to be made on an individual, case by case basis," she said. "I don't think there should be any sweetened beverages in our schools."

The reality check say Oxford researchers is that just because sports drinks may be good for Olympians does not necessarily mean they are good for the rest of us, especially children.