Water may be the stuff of life but it is not necessarily the stuff of exercise. So suggest the manufacturers of a number of leading sports drinks, who argue that water is not nearly as good for maintaining proper hydration while competing or working out. Hugh Westbrook asks are theses valid scientific claims or are they just an exercise in marketing?

Those in both the water and sports drinks market agree on the need for adequate hydration. Water companies and organisations emphasise that drinking at least eight glasses per day is vital simply to keep the body functioning. Sports drinks manufacturers point out that dehydration promotes fatigue which affects performance. There is consensus over the view that it is important to drink enough to maintain peak performance. Disagreement comes over what to drink.

So why do sports drinks manufacturers argue that water is not best. US group Gatorade has developed an entire industry for promoting the health aspects of its products, including a dedicated website (www.gssiweb.com) which provides extensive information on all aspects of sports nutrition.

Gatorade's principal argument is that water "turns off" the body's thirst mechanism before the body is completely rehydrated, meaning that insufficient liquid is absorbed. In addition, the company says that water lacks the carbohydrates needed to provide energy to boost performance, has no sodium, meaning that too much fluid is lost quickly through urine as the kidneys are activated quickly, and does not contain potassium to replace liquid lost through sweat. The messages are put forward forcibly on the company's promotional literature and packaging, as well as on the website.

"The search for solutions for rehydration problems with diseases such as cholera, found that pure water was not adequate"
Professor Clyde Williams

Professor Clyde Williams, chairman of the Gatorade Sports Science Institute (GSSI) Europe, told just-drinks.com that a body of scientific evidence backs up the claims. "The development of sports drinks started with the search for solutions for rehydration problems with diseases such as cholera, when it was found that pure water was not adequate." He explained that the increased level of sodium in sports drinks, combined with glucose, enabled fluid to be absorbed much faster than when drinking water.

He said that the claim that water "turns off" the thirst mechanism was based on tests to determine osmolality, which analyses the number of particles in the blood. An experiment was carried out on subjects drinking water, sports drinks and soft drinks. The results showed that the particles present in the blood indicated to the brain that someone's thirst was satisfied more quickly with water than with the other drinks, even though they may not have been fully rehydrated, he said.

In addition, he said that studies had demonstrated how tastes change during exercise. "Orange may taste good normally, but after exercise, you need a more bitter taste, such as lemon," he explained

So what do water companies say to this. The Natural Mineral Water Information Service in the UK (www.naturalmineralwater.org) believes there is little difference between water and sports drinks. The organisation, sponsored by six mineral water groups in the UK, told just-drinks that while heavy exercise of more than an hour may require someone to drink more than water, for normal exercise water is sufficient.

Quoting The American College of Sports Medicine, it said: "They recommend that whilst athletes exercising for more than one hour may require additional amounts of carbohydrates and/or electrolytes in a fluid replacement solution, for those exercising for less than one hour (the majority of people) there is no added benefit of consuming such drinks in place of plain water."

Not true, counters Professor Williams, who says this opinion is not tested under different conditions such as the intensity of the exercise, the temperature and crucially the amount that someone has eaten prior to exercising, which can effect the hydration solution chosen. "With well-fed people, the difference between water and sports drinks is smaller," he said.

The NMWI adds that the issue of taste is one of personal choice, contrary to Professor Williams' assertions. Choice is very much the opinion of the US-based International Bottled Water Association (www.bottledwater.org). Spokesman Stephen Kay told just-drinks that while bottled water is one of the choices available to athletes, "you can't go wrong with water." He added that the organisation was not necessarily involved in saying water was better or worse than other solutions. It is simply interested in better hydration.

As for the issue of carbohydrates and glucose, the NMWI points out that water may not provide energy but is the catalyst for every physical process that takes place in the body. It adds that it does contain sodium, though Professor Williams said that the amounts contained therein are not significant enough to have an effect. Nevertheless, the presence of sodium means that Gatorade's promotional literature, which says that water has no sodium in it, is technically incorrect.

"Water may not provide energy but is the catalyst for every physical process that takes place in the body"

So which side of the argument is correct? An independent view comes from Dr Barbara Levine, a nutritionist with the Rockefeller Institute. She told just-drinks that the sole issue is "the need to replace fluids." Dr Levine has had experience with a number of athletes, and she said the biggest problem with sports drinks is the weight gain. "One person added 3,600 calories a day just from sports drinks," she said. She added that most weight loss associated with exercise could be put back relatively easily by drinking water. She feels that sports drinks are "marketing hype".

The weight gain issue is one she feels companies such as Gatorade may address in the future with low-calorie lines. It is also worth noting that the company has recently launched Propel Fitness Water, which is a flavoured water without the calorific content of sports drinks, which addresses competition from the water market.

Those in the marketing and production of sports drinks are in little doubt that the argument regarding their products and water has already been won. Others feel that regular water consumption is perfectly adequate. Whatever the truth, if that can be established, the debate is set to exercise minds for some time to come.

Global Packaged Water Report 2000

Global Sports & Energy Drinks Report 2000