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The hazards of too much water

July 01, 2008

We’ve all been told it’s important to drink plenty of fluids during exercise. But now it seems too much water can be very dangerous. So which is right? Both. Good hydration is important, but overhydration can be hazardous, even lethal. Common sense and moderation can help protect you from both extremes, reports the July 2008 issue of Harvard Men’s Health Watch.

Dehydration increases the risk of muscle cramps, heat exhaustion, and heat stroke during exercise in warm weather. And even in mild weather, dehydration can leave exercisers groggy for hours afterward. When the hazards of dehydration became apparent, experts began to encourage drinking fluids during exercise. Guidelines were formulated to meet the needs of elite male athletes whose high-intensity exercise produced lots of fluid loss in sweat. As a result, athletes began to increase fluid intake, and some drank too much, leading to water intoxication and hyponatremia (low blood sodium levels). Hundreds of cases and a number of deaths have been recorded in medical journals.

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