Everyone knows that when you exercise you have to drink plenty of water to avoid dehydration and that during exercise no amout of water is too much. The more the better, keep it coming, drink all the water you can, every chance you get!

Now some new studies on the subject suggest that this way of thinking may not be entirely accurate, so I invite you to review these facts.

In 2003, the USA Track & Field (the governing body for athletics in America), produced new guidelines urging anyone who jogs, cycles or power walks regularly, not to take in huge amounts of water.

Experts are not advocating a ban on work-out fluids. As a rule of thumb, it is accepted that the average adult loses about one liter of fluid a day through sweat and other bodily processes. This is the equivalent of four glasses of water, but those losses increase considerably during exercise.

Dr. David Martin (an exercise physiologist at Georgia State University), who has studied the drinking habits of joggers, said the change in recommendations was long overdue. "We are very worried about the increasingly large groups of people who are taking up running for the first time. They are told from the party line, "Make sure you drink. You can't drink too much. Carry water with you or you will get dehydrated. Don't worry about the heat, just drink more. But that's wrong, wrong, wrong," he said.

British experts agree. "Drinking water at every opportunity can cause serious problems, such as hyponatraemia or water intoxication," said Dr. Dan Tunstall Pedoe, the London Marathon medical director. "That leads to diluted sodium and other body salts, or electrolytes, in the blood. This can cause dizziness and respiratory problems. Some people collapse because of it, which happens quite frequently during the marathon."

Louise Sutton (a sports dietitian and lecturer in health and exercise science at Leeds Metropolitan University), said, "It is a common myth that you can't drink enough when you work out. In fact, it is relatively easy to overdo it." In one hour of any endurance activity you can expect to lose around a litre of fluid through sweat, and more in hot weather.

Water acts as an essential internal cooling mechanism and failing to replace some of those losses will result in dehydration, possibly leading to heatstroke as body temperature soars.

The latest findings show that we don't need to drink as much as was once thought. One cup every hour during exercise is the new recommendation by the USA Track and Field governing body.